U.S. patent application number 15/812825 was filed with the patent office on 2018-05-17 for controlling layer separation in stereolithographic fabrication.
The applicant listed for this patent is Desktop Metal, Inc.. Invention is credited to Yet-Ming Chiang, Ricardo Fulop, Michael Andrew Gibson, Olivia Molnar Lam, Jonah Samuel Myerberg, Michael J. Tarkanian, Jay Collin Tobia.
Application Number | 20180134029 15/812825 |
Document ID | / |
Family ID | 62106553 |
Filed Date | 2018-05-17 |
United States Patent
Application |
20180134029 |
Kind Code |
A1 |
Myerberg; Jonah Samuel ; et
al. |
May 17, 2018 |
CONTROLLING LAYER SEPARATION IN STEREOLITHOGRAPHIC FABRICATION
Abstract
Systems, methods, and components are disclosed for controlling
layer separation in stereolithographic fabrication of
three-dimensional objects. Each layer of the three-dimensional
object can be cured and separated in discrete portions to
facilitate controlling forces in the layers of a three-dimensional
object. For example, controlling curing and separation of layers of
a three-dimensional object according to the systems, methods, and
components disclosed can facilitate accurately forming the
three-dimensional object from cured particle-loaded resins. More
specifically, particle loading can decrease the shear strength of
the cured resin and, thus, controlling the forces exerted on a
given layer of a cured particle-loaded resin can be particularly
useful for reducing the likelihood of deformation in a
three-dimensional object including the particles. In turn, the
accurately formed three-dimensional object including the particles
can be densified to form a dimensionally accurate finished
part.
Inventors: |
Myerberg; Jonah Samuel;
(Lexington, MA) ; Gibson; Michael Andrew; (Boston,
MA) ; Fulop; Ricardo; (Lexington, MA) ;
Tarkanian; Michael J.; (West Roxbury, MA) ; Chiang;
Yet-Ming; (Weston, MA) ; Tobia; Jay Collin;
(Cambridge, MA) ; Lam; Olivia Molnar; (Burlington,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Desktop Metal, Inc. |
Burlington |
MA |
US |
|
|
Family ID: |
62106553 |
Appl. No.: |
15/812825 |
Filed: |
November 14, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62421716 |
Nov 14, 2016 |
|
|
|
62474014 |
Mar 20, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61K 6/807 20200101;
B22F 3/1055 20130101; B22F 2998/10 20130101; B22F 7/04 20130101;
A61K 6/818 20200101; C04B 35/638 20130101; G03F 7/70416 20130101;
B29C 64/165 20170801; B29C 64/135 20170801; G03F 7/0047 20130101;
A61K 6/833 20200101; B22F 1/02 20130101; B29C 64/129 20170801; B33Y
70/00 20141201; G03F 7/027 20130101; B33Y 10/00 20141201; C04B
35/6263 20130101; B22F 1/0059 20130101; C04B 35/632 20130101; G03F
7/0037 20130101; C04B 35/6264 20130101; B22F 3/008 20130101; B33Y
50/02 20141201; B22F 3/26 20130101; A61L 27/46 20130101; B29C
64/124 20170801; B29K 2509/02 20130101; B22F 7/08 20130101; A61K
6/822 20200101; B22F 3/1021 20130101; C04B 35/486 20130101; C04B
35/63488 20130101; B28B 1/001 20130101; B22F 2998/10 20130101; B22F
3/008 20130101; B22F 3/1021 20130101; B22F 3/26 20130101 |
International
Class: |
B33Y 50/02 20060101
B33Y050/02; G03F 7/20 20060101 G03F007/20; B28B 1/00 20060101
B28B001/00; B22F 3/10 20060101 B22F003/10; B22F 3/105 20060101
B22F003/105; B22F 7/04 20060101 B22F007/04; B29C 64/135 20060101
B29C064/135 |
Claims
1. A method of additive manufacturing, the method comprising:
providing a layer of a resin on a media source disposed within a
working volume defined by a build chamber; curing discrete portions
of the layer of the resin on a substrate carried on a surface of a
build plate in the working volume; separating the cured discrete
portions of the layer from the media source, wherein the separation
of at least one of the cured discrete portions is independent of
the separation of at least another one of the cured discrete
portions; and for a plurality of layers, repeating the steps of
providing each respective layer of the resin, curing discrete
portions of each respective layer of the resin, and separating the
cured discrete portions of each respective layer of the resin to
form a three-dimensional object.
2. The method of claim 1, wherein the resin includes particles
suspended in at least one binder, and curing discrete portions of
each respective layer of the resin includes crosslinking or
polymerizing the at least one binder.
3. The method of claim 1, wherein curing the discrete portions of
each respective layer includes, along each discrete portion of the
respective layer of the resin, directing light energy into the
working volume through a transparent portion of the media source,
the light energy sufficient to cure at least one component of the
resin.
4. The method of claim 3, wherein separating the cured discrete
portions of each respective layer of the resin from the media
source includes moving one or both of the build plate and the
transparent portion of the media source relative to one
another.
5. The method of claim 4, wherein separating the cured discrete
portions of each respective layer of the resin from the media
source includes substantially continuously moving of one or both of
the build plate and the transparent portion of the media source
relative to one another.
6. The method of claim 5, wherein curing the discrete portions of
each respective layer of the resin includes substantially
continuously curing adjacent discrete portions of the respective
layer of the resin.
7. The method of claim 4, wherein separating the cured discrete
portions of each respective layer of the resin from the media
source includes moving one or both of the build plate and the
transparent portion of the media source in a direction having a
component parallel to the layer of the resin.
8. The method of claim 7, wherein each discrete segment of each
respective layer of the resin spans a dimension of the surface of
the build plate.
9. The method of claim 8, wherein separating the cured discrete
portions of each respective layer of the resin from the media
source includes moving the transparent portion of the media source
in a direction transverse to the spanned dimension of the surface
build plate.
10. The method of claim 1, wherein at least one cured discrete
portion of each respective layer of the resin is separated from the
media source before curing at least another discrete portion of the
respective layer.
11. The method of claim 10, wherein at least one cured discrete
portion of each respective layer of the resin is separated from the
media before curing an adjacent discrete portion of the respective
layer of the resin.
12. A stereolithography system comprising: a build chamber defining
a working volume; a build plate disposed within the working volume,
the build plate having a surface; an activation light source; and a
media source disposed within the working volume, the media source
including a transparent portion, the activation light source
positioned to direct activation light, through the transparent
portion of the media source, to the surface of the build plate, and
one or both of the build plate and the transparent portion of the
media source movable relative to one another to change a position
of the transparent portion of the media source by an increment
substantially equal to a width of the transparent portion of the
media source in a direction parallel to the surface of the build
plate.
13. The system of claim 12, wherein the width of the transparent
portion of the media source is less than a dimension of the surface
of the build plate in a direction of the changed position of the
transparent portion of the media source.
14. The system of claim 12, wherein the transparent portion of the
media source is movable relative to the build plate along the
direction parallel to the surface of the build plate.
15. The system of claim 12, wherein the build plate is movable
relative to the transparent portion of the media source along the
direction parallel to the surface of the build plate.
16. The system of claim 12, wherein the media source further
includes a dispersion section, a collection section, and a
reservoir in fluid communication with the dispersion section and
the collection section, the dispersion section along a first side
of the transparent portion of the media source, the collection
section along a second side, different from the first side, of the
transparent portion of the media source, and the dispersion section
and the collection section.
17. The system of claim 16, wherein the media source further
includes a blade movable to spread resin from the dispersion
section across the transparent portion of the media source.
18. The system of claim 12, wherein the transparent portion of the
media source spans a dimension of the surface of the build
plate.
19. The system of claim 18, wherein at least one of the build plate
and the transparent portion of the media source is movable in a
direction transverse to the spanned dimension of the surface of the
build plate.
20. The system of claim 12, wherein the activation light source is
a light source having a wavelength of about 300 nm to about 350 nm.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C. .sctn.
119(e) of U.S. Prov. App. No. 62/421,716, filed Nov. 14, 2016, and
U.S. Prov. App. No. 62/474,014, filed Mar. 20, 2017, with the
entire contents of each of these applications hereby incorporated
herein by reference.
BACKGROUND
[0002] Stereolithography is an additive manufacturing technique for
fabricating a three-dimensional object. Systems using this
technique control the incidence of a light source on a liquid
polymer to cause controlled, local hardening of the polymer and,
ultimately, to build the three-dimensional object layer-by-layer.
The result is a three-dimensional object made of one or more
polymers and, thus, subject to the physical limitations of those
constituent polymers.
SUMMARY
[0003] Systems, methods, and components are disclosed for
controlling layer separation in stereolithographic fabrication of
three-dimensional objects. Each layer of the three-dimensional
object can be cured and separated in discrete portions to
facilitate controlling forces in the layers of a three-dimensional
object. For example, controlling curing and separation of layers of
a three-dimensional object according to the systems, methods, and
components disclosed can facilitate accurately forming the
three-dimensional object from cured particle-loaded resins. More
specifically, particle loading can decrease the shear strength of
the cured resin and, thus, controlling the forces exerted on a
given layer of a cured particle-loaded resin can be particularly
useful for reducing the likelihood of deformation in a
three-dimensional object including the particles. In turn, the
accurately formed three-dimensional object including the particles
can be densified to form a dimensionally accurate finished
part.
[0004] According to one aspect, a resin can include a first binder,
a second binder different from the first binder and in a mixture
with the first binder, and particles (e.g., metal, ceramic, or a
combination thereof) suspended in the mixture of the first binder
and the second binder. The particles can be thermally processable
to coalesce with one another into a mass, at least one of the first
binder and the second binder can be reactive to crosslink or
polymerize upon sufficient exposure of the first binder and the
second binder to a predetermined wavelength of light, and the first
binder and the second binder can be separately extractable from the
mass following crosslinking or polymerization of the at least one
of the first binder and the second binder.
[0005] In some implementations, the particles can be sinterable to
coalesce with one another into the mass. Further or instead, the
particles can be infiltratable with a liquid metal to coalesce with
one another into the mass.
[0006] In certain implementations, the first binder can be
substantially non-reactive under exposure to the predetermined
wavelength of light sufficient to cross-link or polymerize the
second binder.
[0007] In some implementations, the first binder can include a wax
extractable from the second binder by chemical solvation in a
non-polar chemical following sufficient exposure of the first
binder and the second binder to the predetermined wavelength of
light to crosslink or polymerize the second binder.
[0008] In certain implementations, the first binder can include a
plurality of low-molecular weight constituents, each constituent
extractable from the second binder by a chemical solution following
sufficient exposure of the first binder and the second binder to
the predetermined wavelength of light sufficient to crosslink or
polymerize the second binder.
[0009] In some implementations, the resin can be a non-Newtonian
fluid at 25.degree. C.
[0010] In certain implementations, exposure to light at a
wavelength of about 300 nm to about 450 nm is sufficient to
crosslink or polymerize at least one of the first binder and the
second binder.
[0011] In some implementations, the resin can further include one
or more of a photo-absorber or a photo-initiator suspended in the
mixture including the first binder and the second binder.
[0012] In certain implementations, a concentration by volume of the
particles in the resin is within .+-.25 percent of a tap density of
the particles.
[0013] In some implementations, the first binder can include one or
more of the following: paraffin wax, carnauba wax, stearic acid,
polyethylene glycol, polyoxymethylene, oleic acid, and dibutyl
phthalate. Further or instead, the second binder can include one or
more of the following: poly(methyl methacrylate), polyethylene
glycol diacrylate, urethane oligomers functionalized to acrylate
groups, epoxy oligomers functionalized to acrylate groups,
1,6-Hexanediol acrylates, or styrene.
[0014] According to another aspect a method of additive
manufacturing of a three-dimensional object can include providing a
layer of a resin on a media source, the resin including particles
suspended in a mixture of a first binder and a second binder,
directing light energy onto each layer of a plurality of layers of
the resin to crosslink or polymerize at least one of the first
binder and the second binder of the resin on a substrate carried by
a build plate, the light energy directed onto the resin in a
respective predetermined pattern associated with each layer to form
a three-dimensional object, thermally processing the particles in
the three-dimensional object to coalesce the particles to one
another, extracting the first binder from the three-dimensional
object in a primary debinding process, and extracting the second
binder from the three-dimensional object in a secondary debinding
process different from the primary debinding process.
[0015] In certain implementations, thermally processing the
particles in the three-dimensional object can include sintering the
three-dimensional object. Additionally, or alternatively, thermally
processing the particles in the three-dimensional object can
include infiltrating the three-dimensional object with a liquid
metal. Further, or instead, thermally processing the particles in
the three-dimensional object can include thermally-activating
pyrolysis of at least one of the first binder and the second binder
into a ceramic.
[0016] In some implementations, one or both of the primary
debinding process and the secondary debinding process can include
thermal debinding, chemical debinding, or a combination
thereof.
[0017] In certain implementations, directing light energy onto each
layer of the plurality of layers of the resin can include
crosslinking or polymerizing the first binder and the second
binder, and the primary debinding process includes breaking down
the crosslinked or polymerized first binder. For example, the first
binder can include acrylic anhydride, methacrylic anhydride, or a
combination thereof.
[0018] According to another aspect, a method of additive
manufacturing can include providing a layer of a resin on a media
source disposed within a working volume defined by a build chamber,
curing discrete portions of the layer of the resin on a substrate
carried on a surface of a build plate in the working volume,
separating the cured discrete portions of the layer from the media
source, wherein the separation of at least one of the cured
discrete portions is independent of the separation of at least
another one of the cured discrete portions, and, for a plurality of
layers, repeating the steps of providing each respective layer of
the resin, curing discrete portions of each respective layer of the
resin, and separating the cured discrete portions of each
respective layer of the resin to form a three-dimensional
object.
[0019] In certain implementations, the resin can include particles
suspended in at least one binder, and curing discrete portions of
each respective layer of the resin can include crosslinking or
polymerizing the at least one binder.
[0020] In some implementations, curing the discrete portions of
each respective layer can include, along each discrete portion of
the respective layer of the resin, directing light energy into the
working volume through a transparent portion of the media source,
the light energy sufficient to cure at least one component of the
resin. For example, separating the cured discrete portions of each
respective layer of the resin from the media source can include
moving one or both of the build plate and the transparent portion
of the media source relative to one another. As another or
additional example, separating the cured discrete portions of each
respective layer of the resin from the media source can include
substantially continuously moving of one or both of the build plate
and the transparent portion of the media source relative to one
another. Further or instead, curing the discrete portions of each
respective layer of the resin can include substantially
continuously curing adjacent discrete portions of the respective
layer of the resin.
[0021] In certain implementations, separating the cured discrete
portions of each respective layer of the resin from the media
source can include moving one or both of the build plate and the
transparent portion of the media source in a direction having a
component parallel to the layer of the resin. Further or instead,
each discrete segment of each respective layer of the resin spans a
dimension of the surface of the build plate. Continuing with this
example, separating the cured discrete portions of each respective
layer of the resin from the media source can include moving the
transparent portion of the media source in a direction transverse
to the spanned dimension of the surface build plate.
[0022] In some implementations, at least one cured discrete portion
of each respective layer of the resin can be separated from the
media source before curing at least another discrete portion of the
respective layer. For example, at least one cured discrete portion
of each respective layer of the resin can be separated from the
media before curing an adjacent discrete portion of the respective
layer of the resin.
[0023] According to still another aspect, a stereolithography
system can include a build chamber defining a working volume, a
build plate disposed within the working volume, the build plate
having a surface, an activation light source, and a media source
disposed within the working volume, the media source including a
transparent portion, the activation light source positioned to
direct activation light, through the transparent portion of the
media source, to the surface of the build plate, and one or both of
the build plate and the transparent portion of the media source
movable relative to one another to change a position of the
transparent portion of the media source by an increment
substantially equal to a width of the transparent portion of the
media source in a direction parallel to the surface of the build
plate.
[0024] In certain implementations, the width of the transparent
portion of the media source can be less than a dimension of the
surface of the build plate in a direction of the changed position
of the transparent portion of the media source.
[0025] In some implementations, the transparent portion of the
media source can be movable relative to the build plate along the
direction parallel to the surface of the build plate.
[0026] In certain implementations, the build plate can be movable
relative to the transparent portion of the media source along the
direction parallel to the surface of the build plate.
[0027] In certain implementations, the media source can further
include a dispersion section, a collection section, and a reservoir
in fluid communication with the dispersion section and the
collection section, the dispersion section along a first side of
the transparent portion of the media source, the collection section
along a second side, different from the first side, of the
transparent portion of the media source, and the dispersion section
and the collection section. The media source can further include a
blade movable to spread resin from the dispersion section across
the transparent portion of the media source.
[0028] In some implementations, the transparent portion of the
media source can span a dimension of the surface of the build
plate. At least one of the build plate and the transparent portion
of the media source can be movable, for example, in a direction
transverse to the spanned dimension of the surface of the build
plate.
[0029] In certain implementations, the activation light source can
be a light source having a wavelength of about 300 nm to about 350
nm.
[0030] According to yet another aspect, a resin can include
particles of a first material, particles of a second material, the
second material different from the first material, and a binder
system in which the particles of the first material and the
particles of the second material are suspended, the particles of
the first material substantially transparent to light of a
wavelength sufficient to crosslink, polymerize, or both, at least
one component of the binder system.
[0031] In certain implementations, the particles of the first
material and the particles of the second material can be
substantially homogeneously suspended in the binder system.
[0032] In some implementations, the particles of the second
material can be substantially opaque to light of the wavelength
sufficient to crosslink, polymerize, or both, the at least one
component of the binder system.
[0033] In certain implementations, the particles of the second
material can have an average size less than the wavelength of the
light sufficient to crosslink, polymerize, or both, the at least
one component of the binder system.
[0034] In some implementations, the particles of the first material
can include a ceramic. Further or instead, the particles of the
second material can include a metal.
[0035] In certain implementations, the first material can be
chemically convertible to the second material. For example, the
first material can be chemically convertible to the second material
via thermally-activated decomposition or reduction.
[0036] In some implementations, the first material can be a metal
oxide reduceable to form a metal.
[0037] In certain implementations, first material can include a
ceramic, an intermetallic, or both, and the particles of the first
material are chemically convertible to a first metal, and the
particles of a second material include a second metal alloyable
with the first metal. The particles of the first material can be in
a relative concentration to the particles of the second material
such that an alloy of the first metal and the second metal meets a
predetermined material standard. Further or instead, an oxide of
the first metal can be less chemically stable than an oxide of the
second metal.
[0038] In some implementations, the binder system can include a
first binder and a second binder, the first binder different from
the second binder and in a mixture with the first binder, and the
first binder substantially non-reactive under exposure to the
wavelength of light sufficient to crosslink or polymerize the
second binder.
[0039] In certain implementations, the first binder can be
extractable from the second binder following exposure of the second
binder to the wavelength of light sufficient to crosslink or
polymerize the second binder.
[0040] According to yet another aspect, a method of additive
manufacturing of the three-dimensional object can include providing
a layer of a resin on a media source, the resin including particles
of a first material, particles of a second material, the second
material different from the first material, and a binder system in
which the particles of the first material and the particles of the
second material are suspended, directing light energy in a
predetermined pattern onto the layer to cure the resin on a
substrate carried by a build plate, the particles of the first
material substantially transparent to the light energy, and the
light energy crosslinking, polymerizing, or both, at least one
component of the binder system, and for each layer of a plurality
of layers, repeating the steps of providing each respective layer
of the resin, and directing light energy in a predetermined pattern
onto each respective layer of the resin to form a three-dimensional
object.
[0041] In certain implementations, the light energy directed onto
each layer can penetrate the respective layer to bond successive
layers of the plurality of layers of the three-dimensional
object.
[0042] In some implementations, the method can further include
sintering the three-dimensional object, the sintering transforming
the particles of the first material to a metal or an additive in a
metallic alloy.
[0043] In certain implementations, the method can further include
removing the binder system from the three-dimensional object
through a plurality of debinding processes.
[0044] In some implementations, the method can further include
infiltrating the three-dimensional object with a liquid metal. For
example, infiltrating the three-dimensional object with the liquid
metal can include replacing the binder system with the liquid
metal.
[0045] Other aspects, features, and advantages will be apparent
from the description and drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1 is a schematic representation of a stereolithography
system.
[0047] FIG. 2 is a flow chart of an exemplary method of fabricating
a three-dimensional object through stereolithography.
[0048] FIG. 3 shows an additive manufacturing system for use with
the stereolithography system of FIG. 1.
[0049] FIG. 4 is a close-up view of a build plate of a
stereolithography system.
[0050] FIG. 5 is a schematic representation of a stereolithography
system.
[0051] FIG. 6 is a schematic representation of a stereolithography
system.
[0052] FIG. 7A is a schematic representation of a fabrication
system of a stereolithography system.
[0053] FIG. 7B is an exploded view of a portion of the fabrication
system of FIG. 7A.
[0054] FIG. 8 is an exploded view of a portion of a media source of
a fabrication system.
[0055] FIG. 9 is a flow chart of an exemplary method of fabricating
a three-dimensional object through stereolithography.
[0056] FIG. 10 is a flow chart of an exemplary method of
fabricating a three-dimensional object through
stereolithography.
[0057] FIG. 11 is a schematic representation of a fabrication
system of a stereolithography system.
[0058] FIG. 12 is a flow chart of an exemplary method of
fabricating a three-dimensional object through
stereolithography.
[0059] FIG. 13 is a schematic representation of a cross-section of
a resin including particles of a first material, particles of a
second material, and a binder system.
[0060] FIG. 14 is a flow chart of an exemplary method of additive
manufacturing of a three-dimensional object using a resin including
particles substantially transparent to light energy.
[0061] FIG. 15 is a flow chart of an exemplary method of additive
manufacturing of a three-dimensional object by forming an alloy
from particles suspended in a resin.
[0062] FIG. 16 is a flow chart of an exemplary method of additive
manufacturing of a three-dimensional object using a resin including
a silicone polymer.
[0063] FIG. 17 is a schematic representation of a cross-section of
a metal particle coated with a material.
[0064] Like reference symbols in the various drawings indicate like
elements.
DESCRIPTION
[0065] Embodiments will now be described with reference to the
accompanying figures. The foregoing may, however, be embodied in
many different forms and should not be construed as limited to the
implementations set forth herein.
[0066] All documents mentioned herein are hereby incorporated by
reference in their entirety. References to items in the singular
should be understood to include items in the plural, and vice
versa, unless explicitly stated otherwise or clear from the text.
Grammatical conjunctions are intended to express any and all
disjunctive and conjunctive combinations of conjoined clauses,
sentences, words, and the like, unless otherwise stated or clear
from the context. Thus, the term "or" and the term "and" should
each generally be understood to mean "and/or.".
[0067] As used herein, the term "substrate" should be generally
understood to be a surface upon which a layer is formed.
Accordingly, the term substrate should be understood to include a
surface of a build plate, a coating on a surface of a build plate,
a previously formed layer of a three-dimensional object being
formed, and combinations thereof, unless otherwise specified or
made clear from the context.
[0068] As used herein, the term "binder system" should be generally
understood to include a plurality of binders, and is used
interchangeably with the recitation of the plurality of binders.
Thus, for example, a first binder and a second binder in a resin
should be understood to be a binder system of the resin, unless
otherwise specified or made clear from the context.
[0069] As used herein, the term "mixture" should be generally
understood to include an aggregate of two or more substances that
are not chemically united and, thus, should be understood to
include a solution of two or more substances.
[0070] Recitation of ranges of values herein are not intended to be
limiting, referring instead individually to any and all values
falling within the range, unless otherwise indicated herein, and
each separate value within such a range is incorporated into the
specification as if it were individually recited herein. The words
"about," "approximately," or the like, when accompanying a
numerical value, are to be construed as indicating a deviation as
would be appreciated by one of ordinary skill in the art to operate
satisfactorily for an intended purpose. Ranges of values and/or
numeric values are provided herein as examples only, and do not
constitute a limitation on the scope of the described embodiments.
The use of any and all examples, or exemplary language ("e.g.,"
"such as," or the like) provided herein, is intended merely to
better describe the embodiments and does not pose a limitation on
the scope of the embodiments. No language in the specification
should be construed as indicating any unclaimed element as
essential to the practice of the embodiments.
[0071] In the following description, it is understood that terms
such as "first," "second," "top," "bottom," "up," "down," and the
like, are words of convenience and are not to be construed as
limiting terms. Thus, particularly, recitation of first and second
should not be construed to imply any particular order.
[0072] Referring now to FIG. 1A, a stereolithography system 100 can
be used to form a three-dimensional object 102 from a resin 104 by
selectively exposing the resin 104 to activation energy from an
activation light source 114. The resin 104 can include particles
(e.g., metal, ceramic, or a combination thereof) suspended in a
plurality of binders, which can include a first binder and a second
binder. While the resin 104 can include the first binder and the
second binder, it should be appreciated that the resin 104 can
include a greater number of binders without departing from the
scope of the present disclosure.
[0073] In general, the second binder can be different from the
first binder and in a mixture with the first binder to form the
resin 104 with characteristics particularly suitable for
stereolithographic fabrication of dense objects. For example, as
described in greater detail below, at least one of the first binder
and the second binder can have an increased resistance to
deformation upon exposure to light having a predetermined
wavelength, and the first binder and the second binder can be
separately extractable from the three-dimensional object 102. Thus,
for example, the first binder and the second binder, in
combination, can address the challenges of handling the resin 104
in the stereolithography system 100 while having mechanical and/or
chemical properties useful for forming the three-dimensional object
102. Through layer-by-layer exposure of the resin 104 to activation
light, a green part, such as the three-dimensional object 102, can
be formed. As also described in greater detail below, the first
binder and the second binder can be extracted (e.g., separately
extracted) from the three-dimensional object 102, and the
three-dimensional object 102 can be densified to form a finished
part. As compared to a part formed only from polymeric materials,
it should be appreciated that the resulting finished part formed
through densification of the particles of the resin 104 can have
improved strength, particularly in instances in which the particles
include metal and/or ceramic material.
[0074] The stereolithography system 100 can be an inverted system
including a media source 106 and a build plate 108. The inverted
orientation of the stereolithography system 100 can facilitate,
among other things, draining excess amounts of the resin 104 from
the three-dimensional object 102 and back toward the media source
106 under the force of gravity. In use, the media source 106 can
carry the resin 104, and the build plate 108 can move in a
direction away from the media source 108 as the three-dimensional
object 102 is built through layer-by-layer exposure of the second
binder in the resin 104 on the media source 106 to activation
light. More specifically, the stereolithography system 100 can
include a build chamber 110 defining a working volume 112, in which
the media source 106 and the build plate 108 can be disposed, and
the stereolithography system 100 can include an activation light
source 114 positioned to direct activation light, as described in
greater detail below, into the working volume 112 in a direction
toward the media source 106 and the build plate 108. Continuing
with this example, light from the activation light source 114 can
be controlled to be incident on the resin 104 carried by the media
source 106 to modify the second binder in the resin 104 in a
predetermined pattern to form a layer of the three-dimensional
object 102 on a substrate (e.g., the build plate 108 or a previous
layer of the three-dimensional object 102).
[0075] The stereolithography system 100 can include a heater 116a,b
in thermal communication with the media source 106 and controllable
to heat the media source 106 to a first target temperature (e.g.,
greater than about 50.degree. C.), thus heating the resin 104
carried by the media source 106. The first target temperature can
be, for example, greater than a melt temperature of the first
binder of the resin 104. Thus, heating the media source 106 can
facilitate spreading the resin 104 on the media source 106 prior to
activating the second binder of the resin 104 and, further or
instead, can facilitate removal of the first binder following
activation of the second binder of the resin 104.
[0076] The heater 116a,b can be any type and number of heaters
sufficient to create a desired thermal profile within the working
volume 112. Accordingly, the heater 116a,b can be spatially
distributed in the working volume 112. Additionally, or
alternatively, the heater 116a,b can transfer heat within the
working volume 112 through conduction, forced convection, natural
convection, radiation, or combinations thereof. As used herein,
conduction includes heat transfer through a medium that is solid,
semi-solid, liquid, or combinations thereof. Thus, for example,
heat transfer from the media source 106 to the resin 104 should be
understood to occur primarily through conduction. Also, as used
herein, convection includes heat transfer through a gaseous medium.
Accordingly, heat transfer from air or another gaseous medium in
the working volume 112 to the three-dimensional object 102 should
be understood to occur primarily through convection. More
generally, it should be understood that a description of a primary
mode of heat transfer should not be understood to foreclose the
possibility of other modes of heat transfer, unless explicitly
stated or made clear from the context.
[0077] An example of heater 116a,b includes a resistance heater
116a in thermal communication with the media source 106. For
example, the resistance heater 116a can be embedded in the media
source 106. Heat can be transferred from the resistance heater
116a, through the media source 106, and into the resin 104 carried
by the media source 106. Heat transfer from the resistance heater
116a to the resin 104 can occur primarily through conductive heat
transfer, and the resistance heater 116a can be controlled to
control the temperature and, thus, one or more properties (e.g.,
flowability) of the resin 104.
[0078] In certain implementations, the resistance heater 116a can
be additionally, or alternatively, in thermal communication with
the build plate 108 such that heat can be transferred (e.g.,
primarily through conductive heat transfer) from the resistance
heater 116a, through the build plate 108, and into the
three-dimensional object 102. As compared to a build plate that is
not heated, heating the build plate 108 can reduce thermal
gradients experienced by the three-dimensional object 102 during
fabrication. For example, the temperature of the build plate 108
can be controlled to a temperature substantially similar to a
temperature of the media source 106. In instances in which the
resistance heater 116a heats the build plate 108 and the media
source 106, portions of the resistance heater 116a heating each of
these components can be separately controllable and/or spatially
separated as necessary to achieve a desired thermal profile along
the media source 106 and the build plate 108.
[0079] As an additional, or alternative, example, the heater 116a,b
can include an ambient heater 116b spaced from the media source 106
(e.g., in a portion of the working volume 112 above the media
source 106). Spacing of the ambient heater 116 from the media
source 106 can be useful, for example, for facilitating separate
control of the temperature of a gaseous medium (e.g., air) in the
working volume 112 relative to the temperature of the resin 104
carried on the media source 106. The ambient heater 116b can be,
for example, a forced convection heater, such as a heater including
a fan moving air over a heating element, arranged to move heated
gas along the portion of the working volume 112 away from the media
source 106. In certain implementations, the ambient heater 116b can
be disposed within the working volume 112 to facilitate efficient
heating of the working volume 112. In some implementations, the
ambient heater 116b can be disposed outside of the working volume
112 and in thermal communication with the working volume 112
through one or more ducts (or similar conduits) to reduce, for
example, thermal stress on components of the ambient heater
116b.
[0080] The heater 116a,b can be controllable (e.g., separately
controllable from the heat provided to the media source 106) to
heat a gaseous medium in a portion of the working volume 112 away
from (e.g., above) the media source 106 to a second target
temperature. In implementations in which the second target
temperature is an elevated temperature (e.g., greater than about
50.degree. C.), heating the gaseous medium in the portion of the
working volume away from the media source 106 can maintain the
first binder of the resin 104 in a molten state to facilitate, for
example, draining the first binder from the three-dimensional
object 102 as the three-dimensional object 102 is built through
layer-by-layer activation of the second binder of the resin 104.
Additionally, or alternatively, heating the gaseous medium in the
portion of the working volume away from the media source 106 can be
useful for controlling thermal gradients experienced by the
three-dimensional object 102 as a portion of the three-dimensional
object 102 is near or in contact with the resin 104 at the first
target temperature while another portion of the three-dimensional
object 102 is away from the resin 104. That is, heating gaseous
medium in the portion of the of the working volume away from the
media source 106 to the second target temperature can facilitate
maintaining the temperature of the three-dimensional object 102
relatively uniform during the fabrication process. This relative
thermal uniformity maintained in the three-dimensional object 102
can, for example, reduce warping or other types of deformation that
can otherwise occur in the presence of large thermal gradients.
[0081] In certain implementations, the second target temperature
corresponding to the gaseous medium in the portion of the working
volume away from the media source 106 can be the same or about the
same (e.g., within about .+-.5.degree. C.) as the first target
temperature of the media source 106 such that the three-dimensional
object 102 and the resin 104 carried by the media source 106 are at
the same or about the same temperature. In such instances, the
repeated introduction and removal of the three-dimensional object
102 into a molten form of the resin 104 can be less likely to
create local solidification of one or both of the first binder and
the second binder of the resin 104. Because such local
solidification can interfere with fabrication of the
three-dimensional object 102, maintaining the second target
temperature to be about the same as the first target temperature
can improve accuracy of the three-dimensional object 102 being
formed.
[0082] The stereolithography system 100 can include one or more
temperature sensors to facilitate controlling the heater 116a,b to
achieve a desired thermal profile within the working volume 112.
For example, the stereolithography system 100 can include a
temperature sensor 118 disposed in a portion of the working volume
112 away from the media source 106. The temperature sensor 118 can
be, for example, a thermocouple or any one or more of various
different types of temperature sensors known in the art and
suitable for measuring an indication of temperature in an
environment. The heater 116a,b can be controllable (e.g., through
feedback control) based on a signal received from the temperature
sensor 118 to heat the gaseous medium in a portion of the working
volume 112 away from the media source 106.
[0083] While the working volume 112 can be heated in various
different ways to achieve any one or more of the various different
advantages described herein, it should be appreciated that certain
portions of the stereolithography system 100 can be advantageously
thermally isolated from the working volume 112 and/or from the
heater 116a,b. For example, the activation light source 114 can be
thermally isolated from the working volume 112 and/or the heater
116a,b to prolong the useful life of the activation light source
114.
[0084] In general, the activation light source 114 can deliver
light of a wavelength (e.g., a predetermined wavelength) and
exposure time suitable to crosslink and/or polymerize one or both
of the first binder and the second binder of the resin 104. The
activation light source 114 can include an ultraviolet light source
in implementations in which the second binder of the resin 104
undergoes crosslinking and/or polymerization upon sufficient
exposure to ultraviolet light. As a more specific example, the
activation light source 114 can include any one or more of various
different ubiquitous light sources that produce light having a
wavelength of about 300 nm to about 450 nm (e.g., about 405 nm,
which corresponds to the Blu-ray Disc' standard). Further, or
instead, the activation light source 114 can produce light within
the daylight frequency, and one or both of the first binder and the
second binder of the resin 104 can include a daylight curable
polymer, such as any daylight curable polymer known in the art.
[0085] In certain implementations, the activation light source 114
can have a wavelength greater than the average size of particles
suspended in the resin 104, which can reduce the likelihood that
the particles will interfere with crosslinking and/or
polymerization of one or both of the second binder of the resin
104. Such reduced interference can, for example, advantageously
reduce the amount of light exposure time required to crosslink
and/or polymerize one or both of the first binder and the second
binder in the resin 104. Further, or instead, reduced interference
can enhance geometric resolution of the three-dimensional object
102 by reducing light scattering.
[0086] The activation light source 114 can be controllable to
provide a pattern of light incident on the resin 104. For example,
the activation light source 114 can include a laser controlled to
rasterize an image on the resin 104. As another, non-exclusive
example, the activation light source 114 can include a digital
light processing (DLP) projector including a plurality of
micromirrors controllable to create an image on the resin 104. As
an additional or alternative example, the activation light source
114 can include one or more light emitting diode (LED)
displays.
[0087] Light from the activation light source 114 can pass through
a portion 117 of the media source 106 that is optically transparent
to the light from the activation light source 114 such that the
presence of the portion 117 of the media source 106 in the light
path produces little to no interference with light directed from
the activation light source 114 to the resin 104 carried by the
media source 106. Thus, for example, in implementations in which
the activation light source 114 includes an ultraviolet light
source, the portion 117 of the media source 106 in the path of the
activation light source 114 can be transparent to ultraviolet
light. Further, or instead, in implementations in which the
activation light source 114 is disposed outside of the working
volume 112, light from the activation light source 114 can pass
into build chamber 110 with little to no interference. While the
media source 106 and/or the build chamber 110 can be optically
transparent to light from the activation light source 114, it
should be appreciated that it may be desirable, in certain
applications, to use one or both of the media source 106 and the
build chamber 110 to filter light from the activation light source
114.
[0088] The stereolithography system 100 can include a controller
120 (e.g., one or more processors) and a non-transitory, computer
readable storage medium 122 in communication with the controller
120 and having stored thereon computer executable instructions for
causing the one or more processors of the controller 120 to carry
out the various methods described herein. For example, the
controller 120 can be in communication with one or more of the
build plate 108, the activation light source 114, the heater
116a,b, and the temperature sensor 118 to control fabrication of
the three-dimensional object 102 based on a three-dimensional model
124 stored on the computer readable storage medium 122. In certain
instances, the stereolithography system 100 can further include a
camera and vision system that can detect parameters (e.g.,
dimensions) of the three-dimensional object 102 as it is formed,
and the computer-readable storage medium 122 can store a digital
twin 126 of the three-dimensional object 102 such that variations
and defects of the three-dimensional object 102 can be
evaluated.
[0089] In general, the resin 104 can be responsive to light, heat,
or a combination thereof controlled by the controller 120 such that
one or both of the first binder and the second binder can be
controllably handled and modified. As a specific example, the
controller 120 can control heat to facilitate spreading the resin
104 along the media source 106 and, further or instead, can control
light along the media source to control a two-dimensional pattern
of crosslinking, polymerization, or both, in one or more of the
first binder and the second binder of the resin 104. The ability to
control accurately the distribution of the resin 104 and
crosslinking or polymerization of one or both of the first binder
and the second binder of the resin 104 can advantageously
facilitate controlling a shape of a layer and, thus, controlling
dimensional features of the three-dimensional object 102 during a
stereolithography process.
[0090] The resin 104 can include particles suspended in a mixture
of the first binder and the second binder. Thus, more specifically,
the particles can be suspended in a solution including the first
binder and the second binder. In general, the particles can be
thermally processable to coalesce with one another, and optionally
with additional material, into a mass. In general, the mass formed
through coalescence of the particles can be denser than the resin
and, thus, can include a porous mass or a solid mass. As used
herein, thermal processing shall be understood to include any
manner and form of coalescence of the particles based on direct or
indirect application of heat. Examples, therefore, of thermal
processing include sintering, infiltration with liquid metal, and
thermally-activated pyrolysis of a polymer-derived ceramic.
Further, in instances in which thermal processing includes
sintering, such thermal processing shall be understood to include
one or more of pre-sintering, solid state sintering, liquid phase
sintering, transient liquid phase sintering, and, more generally,
any manner and form of sintering known in the art.
[0091] At least one of the first binder and the second binder can
be reactive to crosslink or polymerize upon sufficient exposure of
the first binder and the second binder to a predetermined
wavelength of light from the activation light source 114. Such
crosslinking or polymerization can, for example, increase the
resistance of the respective binder to deformation. That is,
crosslinking or polymerizing at least one of the first binder and
the second binder can facilitate maintaining a shape of the
three-dimensional object and, accordingly, can improve reduce the
likelihood of unintended deformation of the three-dimensional
object as the three-dimensional object undergoes post-processing to
form a finished part.
[0092] In certain implementations, the first binder and the second
binder can each be separately extractable from a coalesced mass of
the particles forming the three-dimensional object 102. That is,
the first binder can be removable from the particles through a
first debinding process, and the second binder can be removable
from the particles through a second debinding process, which can be
different from the first debinding process and/or temporally
separate from the first debinding process.
[0093] The physical properties of the first binder and the second
binder can be changed through a selective and controlled
application of energy (e.g., light, heat, or a combination thereof)
during a stereolithographic process to address different
requirements associated with different stages of the
stereolithographic process, such as handling (e.g., spreading) the
resin 104, forming the three-dimensional object 102 layer-by-layer,
and finishing the three-dimensional object 102 into a dense part
formed primarily of the particles. For example, as described in
greater detail below, the first binder and the second binder can
have different melt temperatures to facilitate, among other things,
decoupling spreading characteristics of the resin 104 from binding
characteristics of the resin 104. Additionally, or alternatively,
the first binder and the second binder can have different responses
to incident light. That is, continuing with a more specific
example, the first binder can be substantially non-reactive under
exposure to wavelengths of light sufficient to crosslink or
polymerize the second binder such that the physical properties of
the second binder can be changed during a stereolithographic
process without significantly changing the physical properties of
the first binder.
[0094] The suspension of particles in the resin 104 can include a
dispersion of particles in a solid or a molten form of a mixture of
the first binder and the second binder. The dispersion of the
particles can be uniform or substantially uniform (e.g., varying by
less than about .+-.10 percent) within the mixture of the first
binder and the second binder. More generally, however, the degree
of uniformity of the particles can be a function of strength and/or
design tolerances acceptable for the fabrication of a finished part
formed from the three-dimensional object 102.
[0095] The first binder and the second binder can be, for example,
miscible with one another such that the mixture of the first binder
and the second binder is homogenous. Alternatively, the first
binder and the second binder can be immiscible with one another. In
such instances, the dispersion of the particles in the mixture of
the first binder and the second binder can be formed or made more
homogeneous by shaking or otherwise agitating a molten form of the
resin 104 prior to or during a stereolithography process.
[0096] One or both of the first binder and the second binder can be
a low molecular weight material (e.g., a monomer or an oligomer),
with the low molecular weight indicative of a low degree of
crosslinking or polymerization. For example, one or both of the
first binder and the second binder can have a molecular weight of
less than about 1000 g/mol. Continuing with this example, the
molecular weight of the respective binder can be increasable from
less than about 1000 g/mol to greater than about 1000 g/mol (e.g.,
greater than about 2000 g/mol) under exposure to the predetermined
wavelength of light sufficient to crosslink or polymerize the
second binder. The resulting crosslinking or polymerization
associated with such an increase in molecular weight of the
respective binder can correspond to curing of the respective binder
such that the resin 104 in a respective layer takes a relatively
stable shape during fabrication of the three-dimensional object
102.
[0097] The first binder and the second binder can have different
melt temperatures to facilitate handling the resin 104 in certain
implementations. For example, the first binder can have a first
melt temperature and the second binder can have a second melt
temperature less than or about equal to the first melt temperature.
In such instances, the flow of the resin 104 can be controlled by
controlling temperature of the resin 104 relative to the melt
temperature of the first binder. As a more specific example, the
first binder can have a first melt temperature less than about
80.degree. C., and the temperature of the media source 106, the
build plate 108, and/or the working volume 112 can be controlled to
be above about 80.degree. C. such that the resin 104 is molten
prior to receiving incident light from the activation light source
114. Additionally, or alternatively, the first binder can have a
melt temperature above about 25.degree. C. such that the resin 104
can be substantially solid (e.g., in the form of a paste) to
facilitate storing the resin 104 in a stable form--with the
particles suspended in the first binder and the second binder--for
a significant period of time, such as multiple weeks or longer. In
certain implementations, the concentration of the particles
suspended in the mixture of the first binder and the second binder
can be such that the resin 104 is a non-Newtonian fluid at
25.degree. C.
[0098] Additionally, or alternatively, the first binder and the
second binder can have different decomposition temperatures. For
example, the first binder can have a first decomposition
temperature, and the second binder can have a second decomposition
temperature greater than the first decomposition temperature such
that the second binder can generally withstand heating to a greater
temperature. For example, the second binder can remain in the
three-dimensional object 102 as the three-dimensional object 102 is
heated further, after the first binder is thermally debound from
the three-dimensional object 102 through a primary debinding
process.
[0099] In general, the first binder can be extractable from the
second binder and/or the material of the particles forming the
three-dimensional object 102 through a primary debinding process,
which can include any of various different processes suited to the
composition of the first binder and compatible with separately
extracting the second binder from the three-dimensional object 102
through a secondary debinding process. For example, the first
binder can include a wax extractable from the second binder by
chemical solvation in a non-polar chemical following exposure of
the second binder to wavelengths of light sufficient to crosslink
or polymerize the second binder. As another, non-exclusive example,
the first binder can include a plurality of low-molecular weight
constituents (e.g., paraffin wax and steric acid), each constituent
extractable from the second binder by the same chemical solution
(e.g., hexane) following exposure of the second binder to
wavelengths of light sufficient to crosslink or polymerize the
second binder. Additionally, or alternatively, the first binder can
include polyethylene glycol extractable from the second binder by
dissolution by water or alcohols following exposure of the second
binder to wavelengths of light sufficient to crosslink or
polymerize the second binder. Still further in addition, or in the
alternative, the first binder can include a wax extractable from
the second binder by supercritical carbon dioxide fluid following
exposure of the second binder to wavelengths of light sufficient to
crosslink or polymerize the second binder. Yet further in addition,
or yet further in the alternative, the first binder can include a
low molecular weight polyoxymethylene extractable from the second
binder by catalytic debinding in nitric oxide vapor. For example,
the polyoxymethylene can melt at a temperature substantially
similar to a temperature at which the second binder is
photopolymerizable. In certain implementations, the first binder
can include polyanhydride extractable from the second binder by
hydrolysis and dissolution in aqueous solution following exposure
of the second binder to wavelengths of light sufficient to
crosslink or polymerize the second binder. In some implementations,
the first binder can include a wax thermally extractable from the
second binder following exposure of the second binder to
wavelengths of light sufficient to crosslink or polymerize the
second binder. The thermal extraction can include, as an example,
boiling the wax at a temperature at which the second binder remains
substantially intact (e.g., substantially retaining its shape) in
the three-dimensional object 102.
[0100] The second binder can be removable from the first binder
and/or from the material of the particles forming the
three-dimensional object 102 through a secondary debinding process,
which can include any of various different processes suited to the
composition of the second binder. For example, the second binder
can be debindable from the three-dimensional object 102 by cleaving
and/or un-polymerizing the second binder (e.g., through one or more
of hydrolyzing or solvolyzing) following crosslinking or
polymerization of the second binder. As a more specific example,
the second binder can include acetal diacrylate, which can be
extractable from the first binder by catalytic debinding in nitric
oxide vapor following exposure of the second binder to a wavelength
of light sufficient to crosslink or polymerize the second binder.
As an additional or alternative example, the second binder can
include anhydride diacrylate, which can be extractable from the
first binder by hydrolysis and dissolution in one or more aqueous
solutions following exposure of the second binder to the wavelength
of light sufficient to crosslink or polymerize the second binder.
Yet further in addition, or further in the alternative, the second
binder can include a saccharide diacrylate (e.g., monosaccharide
diacrylate, disaccharide diacrylate, or a combination thereof),
each of which can be extractable from the first binder by
hydrolysis in one or more aqueous solutions including a catalyst
(e.g., a catalyst including one or more biological enzymes, such as
amylase) for hydrolysis of the crosslinked or polymerized second
binder following exposure of the second binder to the wavelength of
light sufficient to crosslink or polymerize the second binder.
Additionally, or alternatively, in instances in which the second
binder is debindable by cleaving and/or un-polymerizing the second
binder, the first binder can have a high molecular weight (e.g.,
greater than about 1000 g/mol) and be present in a small volume
percentage (e.g., less than about 10 percent) in the resin 104.
[0101] In certain implementations, the first binder and the second
binder both can be crosslinked or polymerized through sufficient
exposure to light of a predetermined wavelength. In such
implementations, the primary debinding process associated with
extracting the first binder from the second binder and/or from the
material of the particles forming the three-dimensional object 102
can include breaking down the crosslinked or polymerized first
binder while the second binder remains cross-linked or polymerized
in the three-dimensional object 102. As a specific example, the
primary debinding process can include applying a catalytic solution
to the three-dimensional object to cause part of the first binder
to depolymerize, dissolve, or otherwise breakdown. An example of a
first binder that can react to light and can be subsequently broken
down in this way include anhydride and methacrylic anhydride. More
generally, the first binder that can be broken down in this way can
include a small molecule with two acylate groups (a diacrylate)
containing one or more anhydride linkages. Continuing with this
example, the acrylates can polymerize upon exposure to ultraviolet
light, and the anhydride linkages can break down in the presence of
water and other molecules.
[0102] The particles suspended in the resin 104 can include, for
example, any one or more of various different metals. Further, or
instead, the particles can include any one or more of various
different ceramics. To facilitate producing a solid part with
substantially uniform strength characteristics along the part, the
particles can have the same composition. Additionally, or
alternatively, the particles have a substantially uniform size. In
certain implementations, the particles can include nanoparticles
(e.g., particles having an average particle size of greater than
about 1 nanometer and less than about 100 nanometers). The
nanoparticles can facilitate thermally processing the
three-dimensional object 102 to form a finished part. As a specific
example, the nanoparticles can facilitate sintering the
three-dimensional object 102 at a lower temperature.
[0103] In certain instances, the particles can have an average size
less than a wavelength of light sufficient to crosslink or
polymerize one or both of the first binder and the second binder,
which can have any of various different advantages described
herein. For example, such a ratio of particle size to the
wavelength of light can reduce the likelihood that particles in the
resin 104 will interfere with the incident light, which can result
in shorter times associated with crosslinking or polymerizing one
or both of the second binder. This reduction in time can, in turn,
reduce the time associated with forming a finished part, which can
be particularly useful for mass production of parts.
[0104] In certain instances, it can be desirable to have a high
concentration of the particles in the resin 104 and, thus, a
comparatively lower concentration of the first binder and the
second binder in the resin 104. A high concentration of the
particles in the resin 104 can, for example, reduce the amount of
the first binder and/or the second binder in the resin 104,
therefore reducing the time and/or energy required to crosslink or
polymerize one or both of the first binder and second binder in the
resin 104. Additionally, or alternatively, a high concentration of
the particles in the resin 104 can reduce the amount of each of the
first binder and the second binder in the resin 104, which can
reduce the amount of time required for extracting the first binder
and the second binder from the three-dimensional object 102. As a
specific example of a high concentration, the concentration (by
volume) of the particles in the resin 104 can be within .+-.25
percent of the tap density of the particles. As used herein, the
tap density of particles is the bulk density of a powder of the
particles after a compaction process specified in ASTM B527,
entitled "Standard Test Method for Tap Density of Metal Powders and
Compounds," the entirety of which is incorporated herein by
reference.
[0105] In some implementations, the particles in the resin 104 can
include modified surfaces. With these modified surfaces, the
particles can exhibit one or more physicochemical characteristics
that differ advantageously from the corresponding one or more
physicochemical characteristics of the underlying material of the
particles. For example, the particles can include chemically
functionalized surfaces such as surfaces having a metal oxide
coating useful for resisting corrosion or other undesired chemical
reactions. Additionally, or alternatively, the particles can
include functional groups useful for resisting settling of the
particles in a mixture of the first binder and the second binder
through steric hindrance. In certain instances, under ambient
conditions (e.g., in air at about 25.degree. C. at atmospheric
pressure and with relative humidity of 20-80%), the particles
suspended in the mixture of the first binder and the second binder
in the resin 104 can have a timescale of settling of greater than
about two weeks, which can facilitate storing the resin 104 in a
stable form for a useful period of time. In some instances, the
settling time of the particles in the resin 104 can be greater than
the amount of time at which the first binder is molten during the
stereolithography process to reduce the likelihood of unintended
settling of the particles as the three-dimensional object 102 is
formed.
[0106] The resin 104 can, further or instead, include one or more
of a photo-absorber (e.g., a Sudan dye) or a photo-initiator
suspended in the mixture of the first binder and the second binder.
Inclusion of one or more of a photo-absorber or a photo-initiator
can facilitate, for example, tuning the resin 104 to achieve a
particular response (e.g., a target curing time for one or more of
the first binder or the second binder) upon exposure to activation
light from the activation light source 114.
[0107] The volumetric composition of the resin 104 can be a
function of, among other things, the composition of the constituent
components of the resin 104. In certain implementations, the second
binder can be about 10 percent to about 50 percent by volume of the
total volume of the resin 104. The first binder can include, for
example, one or more of the following: paraffin wax, carnauba wax,
stearic acid, polyethylene glycol, polyoxymethylene, oleic acid,
and dibutyl phthalate. The second binder can include, for example,
one or more of the following: poly(methyl methacrylate),
polyethylene glycol diacrylate, urethane oligomers functionalized
to acrylate groups, epoxy oligomers functionalized to acrylate
groups, 1,6-Hexanediol acrylates, or styrene. Additionally, or
alternatively, the resin 104 can include one or more of the
following mixed with the first binder, the second binder, and the
particles: ethylene vinyl acetate, a slip agent (e.g., stearic
acid), and/or a compatibilizer (e.g., metal stearate (e.g., zinc
stearate), stearic acid, or a combination thereof). In an exemplary
formulation, the first binder can include polyethylene glycol and
the second binder can include poly(methyl methacrylate). For
example, polyethylene glycol can be about 40-90 percent of the
combined weight of the first binder and the second binder and
poly(methyl methacrylate) can be about 10-60 percent of the
combined weight of the first binder and the second binder. In
another exemplary formulation, the first binder can include
paraffin wax and the second binder can include a waxy or
hydrophobic diacrylate oligomer.
[0108] FIG. 2 is a flowchart of an exemplary method 200 of
fabricating a three-dimensional object using any one or more of the
various different stereolithography systems described herein. For
example, the exemplary method 200 can be implemented as
computer-readable instructions stored on the computer-readable
storage medium 122 (FIG. 1) and executable by the controller 120
(FIG. 1) to operate the stereolithography system 100 (FIG. 1) to
form the three-dimensional object 102 (FIG. 1).
[0109] As shown in step 202, the exemplary method 200 can include
providing a resin to a media source. The media source can be, for
example, disposed within a working volume defined by a build
chamber. Further, or instead, the resin can be any of the various
different resins described herein and, thus, can include particles
suspended in a mixture of a first binder and a second binder.
[0110] Providing the resin to the media source can include
depositing the resin on the media source. For example, the resin
can be moved through a dispensing section, such as a nozzle, of the
media source, and the dispensing section can be, optionally, heated
to a temperature greater than the melt temperature of the first
binder of the resin such that the resin becomes molten to
facilitate flow through the dispensing section and spreading along
the media source. Providing the resin to the media source can
additionally, or alternatively, include moving a solid feedstock of
the resin into a working volume of the stereolithography system.
For example, the feedstock can be moved into the working volume
from a storage container thermally isolated from the working
volume. Such thermal isolation can be useful, for example, for
maintaining the feedstock in a solidified form such that the
particles of the resin can remain suspended for a substantial
period of time. More generally, providing the resin to the media
source can include moving the resin with any one or more of the
fabrication systems described herein, such as any one or more of
the fabrication systems described below.
[0111] Providing the resin can include dispersing the resin to form
a layer of resin on a substrate. The thickness of the layer of
resin can represent the resolution of the stereolithography process
and, thus, a small layer thickness can be useful for fabricating
parts with a high degree of spatial resolution (e.g., fewer
errors). Also, or instead, a small layer of thickness can be useful
for increasing the likelihood that activation light can
sufficiently penetrate the layer to activate at least one of the
first binder and the second binder along the depth of the layer. In
certain implementations, the layer of the resin can be, for
example, less than about 200 .mu.m.
[0112] As shown in step 204, the exemplary method 200 can,
optionally, include heating the media source to a first target
temperature. The first target temperature can be greater than a
melt temperature of a first binder (e.g., greater than about
50.degree. C.). It should be understood that heating the media
source to the first target temperature can be useful for
maintaining the resin in a molten form, which can facilitate
spreading the resin along the media source. Heating the media
source can include any of the various different heating methods
described herein and, thus, can include conductively heating the
media source (e.g., through a resistance heater in contact with or
embedded in the media source).
[0113] In certain implementations, the exemplary method 200 can
additionally, or alternatively, include heating a gaseous medium in
a portion of the working volume away from the media source to a
second target temperature (e.g., greater than about 50.degree. C.)
according to any of the various different methods described herein.
The light energy can be directed in a predetermined pattern onto a
layer of resin with the air in the portion of the working volume
away from the media source at the second target temperature, which
can be useful for reducing thermal gradients in the
three-dimensional object being fabricated, as described herein.
[0114] As shown in step 206, the method can include directing light
energy to the media source. For example, the light energy can be
directed to the media source with the media source at the first
target temperature and, thus, with the first binder in a molten
state. The light energy can be received from any of the various
different activation light sources described herein and, therefore,
can include light energy in or near the ultraviolet range.
[0115] The light energy can be directed to the media source, and
thus to the resin, in a predetermined pattern corresponding to
dimensions received from a three-dimensional model forming the
basis of the three-dimensional object being fabricated. The light
energy can be made incident on the media source, and thus on the
resin, for a time sufficient for at least one of the first binder
and the second binder to undergo modification, such as any one or
more modifications described herein. Further or instead, the step
206 of directing light energy can be repeated as necessary to
direct light energy onto each layer of a plurality of layers of the
resin to cure the resin on a substrate carried by the build plate.
The light energy can be directed onto the resin in a respective
predetermined pattern associated with the respective layer to form
the three-dimensional object.
[0116] As shown in step 208, the exemplary method 200 can include
thermally processing particles in the three-dimensional object
according to any one or more of the thermal processes described
herein. Thus, thermally processing the particles can include any
manner and form of applying heat to densify the three-dimensional
object (e.g., with the densification including coalescence of the
particles with one another and, optionally with one or more other
materials, to form a mass). For example, thermally processing the
particles in the three-dimensional object can include sintering the
particles. Further, or instead, thermally processing the particles
in the three-dimensional object can include infiltrating the
three-dimensional object with a liquid metal. Still further or
instead, thermally processing the particles in the
three-dimensional object can include thermally-activated pyrolysis
of a polymer-derived ceramic. In general, thermally processing the
particles can be carried out in a post-processing station, as
described in greater detail below.
[0117] As shown in step 210, the exemplary method 200 can include
extracting a first binder from the three-dimensional object. The
extraction of the first binder from the three-dimensional object
can be carried out in a primary debinding step that leaves
substantially all of the second binder and the material of the
particles remaining in the three-dimensional object. The primary
debinding process can include any one or more debinding processes
known in the art and, therefore, can include one or more of thermal
debinding and chemical debinding (which can include catalytic
debinding), as appropriate based on the composition of the first
binder.
[0118] Referring now to FIGS. 1 and 3, an additive manufacturing
system 300 can include the stereolithography system 100, a conveyor
304, and a post-processing station 306. In use, the
three-dimensional object 102, in the form of a green part, can be
moved along the conveyor 304 and into the post-processing station
306, where the first binder and the second binder can be extracted
from the three-dimensional object 102 and/or where the
three-dimensional object 102 can undergo thermal processing to form
a final part. As an example, the three-dimensional object 102 can
undergo one or more of thermal debinding and chemical debinding to
remove the first binder and the second binder from the
three-dimensional object 102.
[0119] In certain implementations, the three-dimensional object 102
can undergo one or more thermal processes in the post-processing
station 306. For example, the three-dimensional object 102 can be
sintered in the post-processing station 306. In addition to
densifying the three-dimensional object 102, sintering can alter
chemical properties of the particles, which can be useful for
transforming certain types of particles to a metal or to an
additive in a metallic alloy in the finished part. Further, or
instead, thermally processing the three-dimensional object 102 in
the post-processing station 306 can include infiltrating the
three-dimensional object 102 with a liquid metal. The infiltration
of the liquid metal into the three-dimensional object 102 can
include, for example, movement of the liquid metal into spaces in
the three-dimensional object 102 through wicking. In some
instances, infiltrating the three-dimensional object 102 with the
liquid metal can include replacing the first binder and the second
binder with the liquid metal. Additionally, or alternatively,
thermally processing the three-dimensional object 102 can include
thermally activated pyrolysis of a polymer-derived ceramic (e.g.,
as described in greater detail below with respect to FIG. 16).
[0120] While the post-processing station 306 is shown as being
separate from the stereolithography system 100, it should be
appreciated that some or all of the post-processing station 306 can
be incorporated into the stereolithography system 100 such that any
one or more of post-processing steps described herein can occur in
the stereolithography system 100.
[0121] While certain embodiments have been described, other
embodiments are additionally or alternatively possible.
[0122] For example, while a build plate has been described, it
should be appreciated that the build plate of any of the various
different stereolithography systems described herein can include
additional or alternative features. For example, referring now to
FIG. 4, a build plate 408 can be useful for reducing errors in
fabricating three-dimensional objects. Unless otherwise specified
or made clear from the context, the build plate 408 should be
understood to be interchangeable with the build plate 108 (FIG. 1)
for use in the stereolithography system 100.
[0123] The build plate 408 can include a build surface 410 and a
coating 412 disposed along the build surface 410. The coating 412
can be adherable to any of the various different resins described
herein (e.g., the resin 104 in FIG. 1). For example, the coating
412 can be adherable to the resin following exposure of the resin
to light sufficient to crosslink and/or polymerize one or both of
the first binder and the second binder. Thus, continuing with this
example, the coating 412 can be adherable to a three-dimensional
object being formed on the build surface 410 (e.g., the
three-dimensional object 102 of FIG. 1). Further, or instead, the
resin can be preferentially adherable to the coating 412 on the
build surface 410 over adherence to a media source (e.g., the media
source 106 in FIG. 1), increasing the likelihood that the resin
will tend to move with the build plate 408 as the build plate 408
is moved away from the media source. Accordingly, as compared to a
system without a coating, the coating 412 can reduce the likelihood
of fabrication errors that would otherwise result from improper or
insufficient adherence of the resin to the build plate 408.
[0124] The coating 412 can include, for example, a first binder, a
second binder, or a combination thereof to facilitate adhering the
resin including the first binder and the second binder to the
coating 412. More specifically, the coating 412 can include the
first binder, the second binder, or a combination thereof, and can
be substantially free of the particles of the resin to further
improve adhesion between the coating 412 and the resin used for a
particular stereolithography fabrication.
[0125] The coating 412 can be provided to the build surface 410
from a coating source at the start of a new build, such as before a
first layer of a three-dimensional object is formed on the build
plate 408. For example, the coating source can include a film of
the coating 412 positionable on the build surface 410 at the start
of a new build. Additionally, or alternatively, the coating source
can include a reservoir of the coating 412, from which the coating
412 can be drawn and delivered (e.g., through a nozzle) to the
build surface 410. Further, or instead, the coating can be manually
positioned on the build surface 410 as part of a set-up
process.
[0126] As another example, while stereolithographic systems have
been described as including certain modes of delivery of a resin to
a media source, other delivery modes are additionally or
alternatively possible. For example, referring now to FIG. 5, a
stereolithography system 500 is analogous to the stereolithography
system 100 (FIG. 1), except as described below or made clear from
the context. The stereolithography system 500 can include a film
502 movable within a working volume to move resin to a media
source, where incident light from an activation light source can
activate a binder in the resin to form a layer of a
three-dimensional object. Examples of materials that can be used to
form the film 502 include, but are not limited to: polypropylene,
polytetrafluoroethylene, and polydimethylsiloxane. More generally,
the film 502 can be substantially transparent to activation light
used to crosslink or polymerize one or both of the first binder or
the second binder such that the film 502 can be disposed between an
activation light source and the resin without interfering with
activation of the first binder and/or the second binder in the
resin.
[0127] In certain implementations, the film 502 can be indexed to
provide a new layer of the resin along the media source at the
beginning of the build of each layer. For example, between each
layer, the film 502 can be indexed according to a dimension of the
media source. Additionally, or alternatively, the film 502 can be
dynamically indexed such that an area of the film 502 corresponding
to resin used in an immediately preceding layer is moved beyond the
media source prior to building an immediately subsequent layer.
Further, or instead, dispersing the resin can additionally or
alternatively include the use of a roll-to-roll configuration in
which a roll of the resin is brought into contact with a roll of
the film 502 such that the resin becomes dispersed on the film
502.
[0128] As still another example, while stereolithographic systems
have been described as being inverted, additional or alternative
configurations are possible. For example, referring now to FIG. 6,
a stereolithography system 600 is analogous to the
stereolithography system 100 (FIG. 1), except as described below or
made clear from the context. The stereolithography system 600 can
be oriented such that a build plate moves downward, into a media
source, as a three-dimensional object is formed layer-by-layer.
[0129] As yet another example, stereolithographic systems can
additionally, or alternatively, include configurations for shearing
discrete portions of each layer of a three-dimensional object being
formed. For example, light energy can be delivered to discrete
portions of any one or more of the resins described herein to cure
the resin, and the cured resin in the respective discrete portion
can be sheared independently of shearing the cured resin in other
discrete portions. As used herein, a "cured resin" shall be
understood to be a resin, such as any one or more of the resins
described herein, including at least one cured binder and may
additionally include one or more uncured binders.
[0130] In general, a layer of a resin carried on a media source can
be cured between the media source and a substrate carried on a
build plate of a stereolithographic system, with the layer of the
cured resin adhering to both the substrate and the media source.
Before a subsequent layer of the resin can be deposited on top of
the current layer of cured resin, the current layer of the cured
resin is separated from the media source. As a specific example,
the current layer of the cured resin can be separated from the
media source through the application of a shear force between the
media source and the current layer. In general, however, resins
loaded with particles, such as described herein, can decrease the
shear strength of the cured resin and, thus, can have an adverse
impact on proper separation of the cured binder from the media
source. Thus, to reduce the likelihood of improper separation in a
cured binder loaded with particles, stereolithographic systems of
the present disclosure can separate discrete portions of each layer
of cured resin from the media source. As compared to separating an
entire layer of a cured resin from a media source, separating
discrete portions of each layer of the cured resin from the media
source can facilitate complete separation of the cured resin from
the media source, which can correspondingly improve accuracy of the
three-dimensional object formed through successively building
layers of the cured resin on top of one another.
[0131] Referring now to FIGS. 7A and 7B, a fabrication system 700
can include a media source 706, a build plate 708, and an
activation light source 714. Unless otherwise specified or made
clear from the context, the fabrication system 700 can be part of
any one or more of the stereolithography systems described herein.
Thus, for example, the fabrication system 700 can be part of the
stereolithography system 100 (FIG. 1), with media source 706 and
the build plate 708 of the fabrication system 700 disposed in the
working volume 112 defined by the build chamber 110.
[0132] The activation light source 714 can be, for example, any one
or more of the activation light sources described herein. Thus, by
way of example and not limitation, the activation light source can
include a light source having a wavelength of about 300 nm to about
350 nm.
[0133] The media source 706 can include a transparent portion 715.
The activation light source 714 can be positioned to direct
activation light into a working volume (e.g., the working volume
112 in FIG. 1) through the transparent portion 715 of the media
source 706 toward a surface 717 of the build plate 708. In use, as
described in greater detail below, the activation light can
selectively cure discrete portions of a layer of a resin on a
substrate (e.g., the surface 717 of the build plate 708 or a
previous layer) carried by the build plate 708 in the working
volume. As also described in greater detail below, one or both of
the build plate 708 and the transparent portion 715 of the media
source 706 can be movable relative to one another. The movement of
the build plate 708 and the transparent portion 715 of the media
source 706 relative to one another can, for example, change an
origin of a shear force on a cured resin between the build plate
708 and the media source 706.
[0134] As an example, one or both of the build plate 708 and the
transparent portion 715 of the media source 706 can be movable
relative to one another to change a position of the transparent
portion 715 of the media source 706 by an increment substantially
equal to a width of the transparent portion 715 of the media source
706 in a direction parallel to the surface 717 of the build plate
708. Through such incremental movement of the transparent portion
715 of the media source 706, the transparent portion 715 of the
media source 706 can be moved in adjacent incremental steps in a
direction parallel to the surface 717 of the build plate 708. As
the transparent portion 715 of the media source 706, light energy
from the activation light source 714 can cure a layer of the resin
in discrete portions. More specifically, in a first increment, the
light energy from the activation light source 714 can cure a first
discrete portion of the layer of resin, in a second increment
adjacent to the first increment, the light energy from the
activation light source 714 can cure a second discrete portion of
the layer of resin, and so forth.
[0135] The transparent portion 715 of the media source 706 can, for
example, span a dimension of the build plate 708. In certain
instances, the transparent portion 715 of the media source 706 can
be movable in a direction transverse to (e.g., substantially
perpendicular to) the spanned dimension of the surface 717 of the
build plate 708. Additionally, or alternatively, the width of the
transparent portion 715 of the media source 706 can be less than a
dimension of the build plate 708 in the direction of the changed
position of the transparent portion 715 of the media source 706
such that a layer of the resin can be cured in multiple discrete
portions. Advantageously, each discrete cured portion of the layer
of the resin can be separated from the transparent portion 715
(e.g., through the application of a shear force) before the
transparent portion 715 is moved to the next position and the next
discrete portion of the layer of the resin is cured. In certain
implementations, the light energy from the activation light source
714 can be directed to discrete portions of a given layer of the
resin as the activation light source 714 moves substantially
continuously across the given layer of the resin. Similarly, shear
force can be applied to the discrete cured portions of the resin in
a substantially continuous manner. In general, curing and
separating discrete portions of a given layer of the resin
substantially continuously can reduce fabrication time.
[0136] In some implementations, the media source 706 can include a
dispersion section 719, a collection section 721, and a reservoir
723 in fluid communication with the dispersion section 719 and the
collection section 721. The dispersion section 719 can be along a
first side of the transparent portion 715 of the media source 706,
and the collection section 721 can be along a second side,
different from the first side, of the transparent portion 715 of
the media source 706. The first side and the second side can be,
for example, opposite one another. In use, resin can be drawn from
the reservoir 723 to the dispersion section 719 (e.g., through the
use of one or more rollers in the reservoir 723). The dispersion
section 719 can include, in some instances, a nozzle (e.g., shaped
as a slit) and, further or instead, can be heated to facilitate
flowing the resin through the dispersion section 719 to the
transparent portion 715 of the media source 706.
[0137] In certain instances, the media source 706 can include a
blade 725 movable to spread resin from the dispersion section 719
across the transparent portion 715 of the media source 706. For
example, the blade 725 can pivot about a point to spread the resin
across the transparent portion 715 of the media source 706.
Additionally, or alternatively, the blade 725 can be movable to
move at least a portion of the resin, such as excess resin from a
previous layer, to the collection section 721. The resin moved to
the collection section 721 can be agitated and/or heated to
decrease the likelihood that particles in the resin will settle in
the reservoir 723.
[0138] While a media source has been described as including a
dispensing section and a collection section on either side of a
transparent portion of the media source, other configurations for
distributing a resin over a transparent portion of the media source
are additionally or alternatively possible. For example, referring
now to FIG. 8, a media source 806 can include a film 807, an
activation light source 814, and a transparent portion 815. Unless
otherwise specified or made clear from the context, it should be
understood that the media source in FIG. 8 can be used in the
fabrication system 700 of FIG. 7A-7B, in addition to or instead of
the media source 706.
[0139] In the media source806, a resin can be disposed on the film
807, and the film 807 can be movable across the transparent portion
815 of the media source 806. For example, the film 807 can be
advanced over the transparent portion 815 of the media source 806
through movement of rollers 827 on other side of the transparent
portion 815. In certain instances, the film 807 can be indexable by
a predetermined width. As a specific example, the film 807 can be
indexable by a width substantially equal to the width of the
transparent portion 815 of the media source 806 such that, as the
transparent portion 815 of the media source 806 is incremented in a
direction parallel to a build surface (e.g., the surface 717 in
FIG. 7A), the film 807 can be indexed with each incremental
movement of the transparent portion 815 of the media source 806. It
should be appreciated that, through such indexing of the film 807
with incremental movement of the transparent portion 815 of the
media source 806, a fresh panel of resin will be disposed over the
transparent portion 815 of the media source 806 at each increment,
before activation light is directed at the resin to cure a discrete
portion of a layer of the resin. The film 807 can be formed of any
one or more of the materials described above with respect to the
film 502 in FIG. 5. More generally, the film 807 can be understood
to be analogous to the film 502 in FIG. 5, unless otherwise
specified or made clear from the context.
[0140] FIG. 9 is a flowchart of an exemplary method 900 of
fabricating a three-dimensional object. Unless otherwise specified
or made clear from the context, the exemplary method 900 can be
implemented using any one or more of the various different
stereolithography systems described herein. For example, the
exemplary method 900 can be implemented as computer-readable
instructions stored on the computer readable storage medium 122
(FIG. 1) and executable by the controller 120 (FIG. 1) to operate
the stereolithography system 100 (FIG. 1) including one or more of
the fabrication systems of FIGS. 7A, 7B, and 8.
[0141] As shown in step 902, the exemplary method 900 can include
providing resin to a media source disposed within a working volume
defined by a build chamber. The resin can be any one or more of the
resins described herein, unless otherwise specified or made clear
from the context. More generally, the resin can include one or more
binders and particles (e.g., metal particles) suspended in the one
or more binders. At least one of the one or more binders can be
curable (e.g., crosslinkable or polymerizable) upon exposure to
energy, such as light of a sufficient wavelength. As an example,
providing the resin to the media source can include moving the
resin from a reservoir as described with respect to FIGS. 7A and
7B. Additionally, or alternatively, providing the resin to the
media source can include moving the resin as described with respect
to FIG. 8.
[0142] As shown in step 904, the exemplary method 900 can include
curing discrete portions of a layer of the resin on a substrate
carried on a surface of a build plate in the working volume. Curing
the discrete portions of the layer can include directing light
energy into the working volume through a transparent portion of the
media source according to any one or more of the methods described
herein. Accordingly, curing discrete portions of the layer of the
resin can include curing the layer of the resin in multiple curing
steps according to any one or more of the discrete curing methods
described herein. Thus, for example, during discrete portions of
the layer of the resin can include substantially continuously
curing adjacent discrete portions of the layer of the resin and, in
concert with such curing, shearing the cured resin in the discrete
portions as part of a substantially continuous process. In certain
instances, each discrete portion can span a dimension of the
surface of the build plate. In such instances, light energy can be
selectively delivered to a layer of resin by moving the transparent
portion of the media chamber in a single direction (e.g.,
transverse to the spanned dimension). Thus, for example, the
transparent portion of the media source and the activation light
source can be arranged as a substantially elongate light bar (such
as the activation light source 714) that can scan the layer of
resin by moving in a single direction substantially parallel to the
surface of the build plate.
[0143] As shown in step 906, the exemplary method 900 can include
separating the cured discrete portions of the layer from the media
source. The separation of at least one of the cured discrete
portions can be done independently of separation of at least
another one of the cured discrete portions. For example, at least
one of the cured discrete portions of the layer can be separated
from the media source before another one of the cured discrete
portions of the layer is formed. As a more specific example, the
step 904 of curing and the step 906 of separating can be performed
alternately as the position of the media source is changed relative
to the surface of the build plate. In sufficiently rapid
succession, alternation of the step 904 of curing and the step 906
of separating can form the basis of a substantially continuous
process applied across a given layer.
[0144] In general, separation of the cured discrete portions of the
layer from the media source can include changing a position of the
transparent portion of the media source relative to the build plate
(e.g., the surface of the build plate). The changed position can
generate a force (e.g., a shear force) on one or more of the cured
discrete portions of the layer to separate each corresponding cured
discrete portion from the media source.
[0145] In certain instances, one or both of the build plate and the
transparent portion of the media source can be movable relative to
one another to generate the force on the one or more cured discrete
portions of the layer. For example, separating the cured portions
of the layer from the media source can include moving one or both
of the build plate and the transparent portion of the media source
in a direction having a component parallel to the layer of the
resin. Additionally, or alternatively, separating the cured
discrete portions of the layer from the media source can include
rotating one or both of the build plate and the transparent portion
of the media source relative to one another. As one example, one or
both of the surface of the build plate and the transparent portion
of the media source can be rotated about an axis substantially
perpendicular to a plane defined by the transparent portion of the
media source.
[0146] As shown in step 908, the exemplary method 900 can include,
for a plurality of layers, repeating the steps of providing resin
to the media source, curing discrete portions of a given layer, and
separating cured discrete portions of the layer can be repeated to
form each layer of a three-dimensional object.
[0147] As shown in step 910, the exemplary method 900 can,
optionally, include moving the build plate (e.g., in a direction
away from the media source) before repeating the steps of providing
resin to the media source, curing discrete portions of a given
layer, and separating cured discrete portions of a given layer.
Moving the build plate in this way can provide spacing necessary
for forming a subsequent layer of the three-dimensional object.
[0148] FIG. 10 is a flow chart of an exemplary method 1000 of
fabricating a three-dimensional object. Unless otherwise specified
or made clear from the context, the exemplary method 1000 can be
implemented using any one or more of the various different
stereolithography systems described herein. For example, the
exemplary method 1000 can be implemented as computer-readable
instructions stored on the computer readable storage medium 122
(FIG. 1) and executable by the controller 120 (FIG. 1) to operate
the stereolithography system 100 (FIG. 1) including one or more of
the fabrication systems of FIGS. 7A, 7B, and 8.
[0149] As shown in step 1002, the exemplary method 1000 can include
providing a resin to a media source disposed within a working
volume defined by a build chamber. The resin can be, for example,
any one or more of the resins described herein, and the media
source can be any one or more of the media sources of the
fabrication systems of FIGS. 7A, 7B, and 8.
[0150] As shown in step 1004, the exemplary method 1000 can include
curing discrete portions of a layer of the resin on a substrate
carried by a build plate in the working volume. In general, curing
discrete portions of the layer of the resin on the substrate can
include any one or more of the methods of curing discrete portions
of the layer described herein. For example, the selective exposure
of each discrete segment can be based on a predetermined pattern
associated with the given segment of the layer. It should be
appreciated that the predetermined patterns of each segment combine
to form an overall predetermined pattern of the given layer.
[0151] As shown in step 1006, the exemplary method 1000 can include
changing the position of the transparent portion of the media
source relative to the build plate by an increment substantially
equal to a width of the transparent portion of the media source.
The change in position of the transparent portion of the media
source can separate at least one of the cured discrete portions
from the media source. In general, changing the position of the
transparent portion of the media source relative to the build plate
can include any one or more methods of changing the relative
position of the media source relative to the build plate described
herein. Thus, for example, changing the position of the transparent
portion of the media source relative to the build plate can include
moving one or both of the build plate and the media source relative
to one another (e.g., to create a shear force in one or more cured
discrete portions of the layer of resin). Further, or instead, the
transparent portion of the media source can be moved in increments
of one width (e.g., with each increment substantially adjacent to a
previous position of the transparent portion) in a direction
substantially parallel to the surface of the build plate as the
discrete portions of the layer of the resin are cured for a given
layer of a three-dimensional object.
[0152] As shown in step 1008, the exemplary method 1000 can
include, for each layer of a plurality of layers, repeating the
steps of providing resin to the media source, curing discrete
portions of a given layer, and separating cured discrete portions
of the given layer can be repeated to a three-dimensional
object.
[0153] As shown in step 1010, the exemplary method 1000 can include
moving the build plate (e.g., in a direction away from the media
source) before repeating the steps of providing resin to the media
source, curing discrete portions of a given layer, and separating
cured discrete portions of a given layer.
[0154] While certain fabrication systems have been described for
delivering resin to discrete planar portions of a layer and curing
each discrete planar portion of the given layer, other
configurations are additionally or alternatively possible. For
example, referring now to FIG. 11, a fabrication system 1100 can be
based on delivering resin and curing resin along a region of
tangential contact between a rolling member and a substrate upon
which a given layer is being formed. The fabrication system 1100
can include media source 1102, a build plate 1104, and an
activation light source 1106. Unless otherwise specified or made
clear from the context, the fabrication system 1100 can be part of
any one or more of the stereolithography systems described herein.
Thus, for example, it should be understood that the fabrication
system 1100 can be part of the stereolithography system 100 (FIG.
1) and, therefore, the media source 1102 and the build plate 1104
of the fabrication system 1100 can be disposed in the working
volume 112 defined by the build chamber 110.
[0155] The activation light source 1106 can be positioned to direct
activation light, through the media source 1102, toward a surface
of the build plate 1104. The activation light source 1106 can be,
for example, any of the various different light sources described
herein. Light energy moving from the activation light source 1106
can pass through a transparent portion 1110 of the media source
1102 and, in some instances, can remain substantially
unchanged.
[0156] The media source 1102 can be rotatable about an axis
substantially parallel to the surface of the build plate 1104 in a
direction R to create a shear force to separate one or more cured
discrete portions of a layer of a resin 1114 from the media source
1102. Thus, for example, as a discrete portion of the layer of the
resin 1114 is cured, the media source 1102 can be rotated (e.g., by
a predetermined amount) to separate the cured discrete portion from
the media source 1102. In addition to the rotational motion of the
media source 1102 in the direction R, one or both of the media
source 1102 can and the build plate 1104 can be movable relative to
the other one of the media source 1102 and the build plate 1104 in
a direction D substantially parallel to a surface 1108 of the build
plate 1104. In general, the components of rotational and
translational relative movement between the media source 1102 and
the surface 1108 of the build plate 1104 can be controlled to
achieve a direction and speed of movement useful for curing and
separating discrete segments of the resin 1114 to form a given
layer of a three-dimensional object. Further or instead, the build
plate 1104 can be movable in a direction perpendicular to the
surface 1108 of the build plate 1104. For example, the build plate
1104 can move in the direction perpendicular to the surface 1108 of
the build plate 1104 following formation of a given layer (e.g., to
make space for a new layer to be built upon the given layer).
[0157] In certain implementations, the media source 1102 can
include a substantially cylindrical tube transparent to light from
the activation light source 1106. For example, the substantially
cylindrical tube can have a longitudinal dimensional substantially
parallel to the surface of the build plate, and the substantially
cylindrical tube can be rotatable about the longitudinal dimension
to move the media source 1102 relative to the substrate upon which
a given layer is being formed. The longitudinal dimension of the
substantially cylindrical tube can span a dimension of the surface
of the build plate 1104.
[0158] In some implementations, the media source 1102 can be
disposed about the activation light source 1106. Such a position of
the media source 1102 about the activation light source 1106 can
facilitate, for example, isolating (e.g., thermally isolating) the
activation light source 1106 from other components of the
fabrication system 1100. For example, in instances in which the
media source 1102 is a substantially cylindrical tube, the
activation light source 1106 can be disposed in an interior portion
of the tube, where the activation light source 1106 can be
protected from heat and debris, among other things.
[0159] In some instances, the fabrication system 1100 can further
include a reservoir 1112. The media source 1102 can be, for
example, partially disposed in the reservoir 1112, with rotation of
the media source 1102 moving a surface of the media source 1102 in
the direction R from the reservoir 1112 toward the surface 1108 of
the build plate 1104. Continuing with this example, as the media
source 1102 rotates in the direction R from the reservoir 1112
toward the surface 1108 of the build plate 1104, the media source
1102 can deliver the resin 1114 to a position between the
activation light source 1106 and the surface 1108 of the build
plate 1104, where light energy from the activation light source
1106 can cure a discrete portion of a layer of the resin. In
addition to delivering resin toward the build plate 1104, rotation
of the media source 1102 in the direction R can return unused resin
1114' to the reservoir 1112.
[0160] The reservoir 1112 can include, for example, at least one
mixer 1116 disposed in the reservoir 1112. The at least one mixer
1116 can include a plurality of blades 1118 rotatable or otherwise
movable in the reservoir 1112 to agitate the resin in the reservoir
1112. Such agitation can, for example, reduce the likelihood that
particles in the resin will settle in the reservoir 1112. Further,
or instead, the fabrication system 1100 can include a heater 1120
in thermal communication with the reservoir 1112. In certain
instances, heat from the heater 1120 can facilitate mixing of the
resin 1114 by the at least one mixer 1116.
[0161] FIG. 12 is a flow chart of an exemplary method 1200 of
fabricating a three-dimensional object using a rotatable media
source. By way of example, the exemplary method 1200 can be
implemented as computer-readable instructions stored on the
computer-readable storage medium 122 (FIG. 1) and executable by the
controller 120 (FIG. 1) to operate the stereolithography system 100
(FIG. 1) including the fabrication system 1100 (FIG. 11).
[0162] As shown in step 1202, the exemplary method 1200 can include
providing a resin to a media source disposed within a working
volume defined by a build chamber. The resin can be, for example,
any one or more of the resins described herein. Providing the resin
to the media source can include, for example, storing the resin in
a reservoir with at least a portion of the media source in contact
with the resin in the reservoir.
[0163] As shown in step 1204, the exemplary method 1200 can include
curing discrete portions of a layer of the resin on a substrate
carried on a surface of a build plate in the working volume. For
example, curing discrete portions of the layer of the resin on the
substrate can include directing light energy through the media
source and at the discrete portions of the layer on the substrate.
In certain instances, directing light energy at the discrete
portions of the layer on the substrate can include pausing rotation
of the media source as light energy is directed at each discrete
portion of the layer.
[0164] As shown in step 1206, the exemplary method 1200 can include
rotating the media source about an axis substantially parallel to
the surface of the build plate. The rotation of the media source
can, for example, separate at least one of the cured discrete
portions from the media source. As the media source is rotated
about the axis substantially parallel to the surface of the build
plate, at least a portion of the media source can move through the
reservoir containing the resin. In particular, the media source can
move through the resin such that resin can be deposited on the
media source and rotation of the media source draws resin out of
the reservoir to a position between the activation light source and
the surface of the build plate. The resin in the reservoir can be
mixed, heated, or both according to any one or more of the methods
described herein.
[0165] Other types of movement of the media source relative to the
surface of the surface of the build plate are additionally, or
alternatively, possible. For example, one or both of the build
plate and the media source can be moved relative to one another to
change a position of the media source relative to the surface of
the build plate in a direction substantially parallel to the
surface of the build plate.
[0166] As shown in step 1208, the exemplary method 1200 can
include, for each layer of a plurality of layers, repeating the
steps of providing the resin to the media source, curing discrete
portions of each given layer, and separating cured discrete
portions of the each given layer to form a three-dimensional
object.
[0167] In some instances, as shown in step 1210, the exemplary
method 1200 can include moving the build plate (e.g., in a
direction away from the media source) before building a subsequent
layer of the three-dimensional object being formed.
[0168] While resins have been described as including particles
suspended in one or more binders, other configurations are
additionally or alternatively possible. For example, as described
in greater detail below, resins can include particles that are
substantially transparent to light of certain wavelengths. In
general, substantial transparency of particles in a resin can
facilitate achieving suitable penetration of light through a layer
of the resin and, in turn, can be useful for forming bonds between
a layer being formed and an immediately preceding layer to form a
three-dimensional object. Stated differently, substantial
transparency of the particles in the resin can usefully overcome
disparate challenges associated with achieving suitable light
penetration in a layer of a resin to achieve sufficient intralayer
bonding while the resin itself includes a high particle loading
useful for forming a dense part.
[0169] Referring now to FIG. 13, a resin 1302 can include particles
of a first material 1304, particles of a second material 1306, and
a binder system 1308 in which the particles of the first material
1304 and the particles of the second material 1306 are suspended
(e.g. substantially homogeneously suspended). The particles of the
second material 1306 can be different from the particles of the
first material 1304. For example, particles of the first material
1304 can be substantially transparent to light of a wavelength
sufficient to crosslink, polymerize, or both at least one portion
of the binder system (e.g., light having a wavelength of about 300
nm to about 450 nm). Additionally, or alternatively, the particles
of the second material 1306 can include a metal or a material
otherwise substantially opaque to light of the wavelength
sufficient to crosslink, polymerize, or both, the at least one
portion of the binder system 1308. Thus, it should be appreciated
that, in a resin having a high loading of particles, the
substantial transparency of the particles of the first material
1304 to light of the wavelength sufficient to crosslink and/or
polymerize at least one portion of the binder system 1308 can
provide a pathway for the penetration of light to a suitable depth
within a layer of a three-dimensional object being formed.
[0170] In certain instances, the particles of the second material
1306 can have an average size less than the wavelength of the light
sufficient to crosslink, polymerize, or both, the at least one
portion of the binder system 1308. Thus, in implementations, in
which the particles of the second material 1306 are substantially
opaque, the particles of the second material 1306 can be sized to
be less likely to interfere with penetration of light into the
resin 1302.
[0171] The particles of the first material 1304 can include, for
example, a ceramic. In some implementations, the ceramic can be
heated or otherwise chemically converted to form a metal suitable
for formation of the three-dimensional object. In certain
instances, at least one portion of the binder system 1308 can be
crosslinkable, polymerizable, or both, through exposure to light of
a wavelength below a band gap of the ceramic. As an example, the
ceramic can include a metal oxide, such as any one or more of iron
oxide, silicon oxide, aluminum oxide, zirconium oxide, and chromium
oxide. Additionally, or alternatively, the ceramic can include a
metal nitride, such as any one or more respective metals selected
from group VII or group VIII elements. Further or instead, the
ceramic can include a metal carbide (e.g., silicon carbide).
[0172] In certain instances, the particles of the first material
1304 can include one or more of an intermetallic and a ternary
oxide.
[0173] The particles of the first material 1304 can be, in certain
applications, chemically convertible to a third material. Thus, for
example, an appropriate first material for certain applications can
include selecting a material that is optically transparent to a
wavelength suitable for cross-linking and/or polymerizing at least
a portion of a binder system 1308 while also being chemically
convertible (e.g., through subsequent processing) to a third
material useful for fabrication of the three-dimensional object. As
a specific example, the first material can be selected such that
the third material is substantially the same composition as the
second material. As a more specific example, the second material
can include copper, and the first material can be copper sulfide.
Additionally, or alternatively, the first material can be selected
for being chemically convertible to a given third material through
a desired process, such as a typical post-process performed on the
three-dimensional object formed through layer-by-layer deposition
of the resin 1302 according to any one or more of the
stereolithography methods described herein. By way of example, the
first material can be selected as being chemically convertible to
the third material via thermally-activated decomposition or
reduction. Thus, in the case in which the third material is
substantially the same composition as the second material, the
first material can be selected as being chemically convertible to
the second material via thermally-activated decomposition or
reduction. Further, or instead, the first material can be a metal
oxide reduceable to form a metal. As described in greater detail
below, the first material can be a material that is chemically
convertible to a material that can be alloyed with the second
material in instances in which the second material includes a
metal.
[0174] The volumetric ratio of the particles of the first material
1304 to the particles of the second material 1306 can be a function
of considerations related to achieving suitable penetration of
light while also producing an acceptable amount of shrinkage in a
three-dimensional object as the first material is converted to the
third material. For example, the particles of the second material
1306 can be greater than about 10 percent by volume and less than
about 30 percent by volume of the resin 1302. Additionally, or
alternatively, the particles of the first material 1304 can be
greater than about 20 percent and less than about 40 percent by
volume of the resin 1302.
[0175] The binder system 1308 can include a first binder and a
second binder. The first binder and the second binder can include
combinations of any one or more of the first binder and the second
binder described herein. Thus, as an example, the first binder can
be substantially non-reactive under exposure to the wavelength of
light sufficient to crosslink or polymerize the second binder and,
additionally or alternatively, the first binder can be useful for
facilitating spreading the resin 1302 as part of a fabrication
process.
[0176] FIG. 14 is a flow chart of an exemplary method 1400 of
additive manufacturing of a three-dimensional object using a resin
including particles substantially transparent to light energy and
suspended in a binder system. Unless otherwise indicated or made
clear from the context, it should be appreciated that the exemplary
method 1400 can be carried out using any one or more of the devices
and systems of the present disclosure.
[0177] As shown in step 1402, the exemplary method 1400 can include
providing a resin to a media source. The resin can include
particles of a first material, particles of a second material, and
a binder system in which the particles of the first material and
the second material are suspended and, thus, more specifically, can
be the resin 1300 in FIG. 13.
[0178] As shown in step 1404, the exemplary method 1400 can include
directing light energy in a predetermined pattern onto a layer of
the resin on the media source. The light energy can modify the
resin, such as by cross-linking, polymerizing, or both, at least
one portion of the binder system. Further, or instead, the
particles of the first material can be substantially transparent to
the light energy, and the light energy can substantially penetrate
the layer (e.g., penetrate the entire thickness of the layer) to
bind a given layer of the resin to an adjacent layer as part of a
fabrication process of the three-dimensional object.
[0179] As shown in step 1408, the exemplary method 1400 can
include, for each layer of a plurality of layers, repeating the
steps of providing resin to the media source, and directing light
energy in a predetermined pattern onto a given layer of the resin
on the media source to form a three-dimensional object.
[0180] While resins have been described as including particles of a
first material and particles of a second material to facilitate
penetration of light into a layer formed by the resin, it should be
appreciated that the first material and the second material can
additionally, or alternatively, be selected to form a desired alloy
in the finished three-dimensional object.
[0181] Referring again to FIG. 13, the particles of the first
material 1304 can include, for example, one or more of a ceramic,
an intermetallic, or other material substantially transparent to
light of a wavelength sufficient to crosslink, polymerize, or both,
at least one portion of the binder system 1308. The particles of
the first material 1304 can be chemically convertible to a first
metal (e.g., via reduction of a metal oxide), and the particles of
the second material 1306 can include a second metal alloyable with
the first metal. Thus, in use, the particles of the first material
1304 can be penetrated by light to bind a given layer to an
adjacent layer and, once a three-dimensional object is formed
through a layer-by-layer stereolithography process, the particles
of the first material 1304 can be converted into a material
alloyable with the second metal. Further, while a first metal and a
second metal are described, it should be appreciated that
additional metals and/or additives can be included in the resin as
necessary to achieve a target alloy formulation in a finished part.
In certain instances, the particles of the first material 1304 can
be in a relative concentration to the particles of the second
material 1306 such that an alloy including the first metal and the
second metal meets a predetermined material standard. For example,
the alloy including the first metal and the second metal can meet
an AISI material standard or other similar industry standard.
[0182] In certain implementations, the first metal and the second
metal can be alloyable into a stainless steel. For example, the
first material can be an iron-based ceramic and the second material
can be one or more of chromium nickel, or alloys thereof. Examples
of the iron-based ceramic include one or more of iron oxide and
iron nitride.
[0183] The selection of an appropriate first material and an
appropriate second material can be based on chemical stability.
That is, because the first material undergoes chemical conversion
to alloy with the second material, it is generally desirable to
select the first material as the material that is more readily
converted. Thus, for example, an oxide of the first metal can be
less chemically stable than oxide of the second metal.
[0184] In certain implementations, particles of the first material
can include a ternary oxide.
[0185] FIG. 15 is a flow chart of an exemplary method of additive
manufacturing of a three-dimensional object by forming an alloy
from particles suspended in a resin. Unless otherwise indicated or
made clear from the context, it should be appreciated that the
exemplary method 1500 can be carried out using any one or more of
the devices and systems of the present disclosure.
[0186] As shown in step 1502, the exemplary method 1500 can include
providing a layer of a resin on a media source. The resin can be
any one or more of the resins described herein and including
particles of a first material, particles of a second material, and
a binder system and, more specifically, with the first material
substantially transparent to light of a wavelength sufficient to
cross-link or polymerize at least a portion of a binder system in
which the particles are suspended, and the first material
chemically convertible into a first metal alloyable with a second
metal of the second material.
[0187] As shown in step 1504, the exemplary method 1500 can include
directing light energy in a predetermined pattern onto the layer of
the resin to cure the resin on a substrate carried by a build
plate.
[0188] As shown in step 1508, the exemplary method 1500 can
include, for each layer of a plurality of layers, repeating the
steps of providing the resin, and directing light energy in a
predetermined pattern onto a given layer of the resin. Unless
otherwise indicated, or made clear from the context the steps 1504
and 1508 should be understood to be analogous to the corresponding
steps 1404 and 1408 described with respect to the exemplary method
1400 (FIG. 14).
[0189] As shown in step 1510, the exemplary method 1500 can include
forming an alloy including the first metal and the second metal.
The alloy can be, for example, an alloy meeting a predetermined
standard, such as one or more industry standards for a given type
of alloy. As an alternative or additional example, the alloy can be
a stainless steel.
[0190] Forming the alloy including the first metal and the second
metal can include thermally processing the three-dimensional
object. In certain implementations, the first material can be
chemically converted to the first metal by sintering the
three-dimensional object at a sintering temperature. Additionally,
or alternatively, forming the alloy including the first metal and
the second metal can include infiltrating (e.g., through wicking)
the three-dimensional object with a liquid metal. The liquid metal
can be, for example, a component of the alloy including the first
metal and the second metal. Further, or instead, the liquid metal
can include a third metal having a composition different from at
least one of the first metal and the second metal.
[0191] In some instances, the exemplary method 1500 can, further or
instead, include debinding the binder system from the
three-dimensional object. By way of example, such debinding can
include any one or more of the debinding processes described
herein.
[0192] While the first material and the second material have been
described as being metal or convertible into a metal, it should be
appreciated that at least one of the first material and the second
material can be an additive useful for forming an alloy. Further,
or instead, it should be appreciated that the first material and
the second material are recited for the sake of clarity of
explanation and, more generally, the resin can include two or more
materials processable (e.g., thermally processable) into an
alloy.
[0193] While resins have been described as including particles of
different compositions to facilitate formation of strong
three-dimensional objects using stereolithographic processes, other
resins are additionally or alternatively possible. For example,
resins can include one or more photopolymers that can be usefully
chemically converted to provide support for a three-dimensional
object formed through a stereolithographic process as the
three-dimensional object is thermally processed to densify and,
ultimately, form a finished part.
[0194] As an example, a resin can include particles of metal (e.g.,
iron) and a binder system in which the particles are suspended. The
binder system can include a photopolymer crosslinkable or
polymerizable upon exposure to light of a predetermined wavelength.
Additionally, or alternatively, the photopolymer can be thermally
decomposable to a first ceramic dissolvable in the metal or an
alloy of the metal at a sintering temperature of the particles of
the metal. Thus, in this way, the ceramic can provide sintering
support for strengthening the three-dimensional part without being
present in significant quantities in the three-dimensional part
after sintering.
[0195] The photopolymer can be, for example, a silicone polymer and
the first ceramic can be silicon carbide. In certain
implementations, the binder system can include a second component
containing carbon. The second component can be chemically
convertible such that the silicon carbide is formed from the carbon
on of the second component.
[0196] In certain instances, the particles of the metal can have an
average size less than the wavelength of the light sufficient to
crosslink or polymerize the photopolymer. Such size can reduce the
likelihood that the particles of the metal will interfere with
penetration of the light in a layer of the resin.
[0197] The molecular weight of the photopolymer can be increasable
from less than about 1000 g/mol to greater than about 1000 g/mol
under exposure to the wavelength of light sufficient to crosslink
or polymerize the photopolymer.
[0198] In general, the particles of metal suspended in the binder
system can have a timescale of settling substantially greater than
the duration of time sufficient for the photopolymer to undergo
crosslinking or polymerization upon exposure to light of the
predetermined wavelength.
[0199] FIG. 16 is a flow chart of an exemplary method 1600 of
additive manufacturing of a three-dimensional object using a resin
including a silicone polymer. Unless otherwise indicated or made
clear from the context, it should be appreciated that the exemplary
method 1600 can be carried out using any one or more of the devices
and systems of the present disclosure.
[0200] As shown in step 1602, the exemplary method 1600 can include
providing a resin to a media source. The resin can include a
silicone polymer and, further or instead, particles of metal
suspended in the silicone polymer. As shown in step 1604, the
exemplary method 1600 can include directing light energy in a
predetermined pattern in onto a layer of the resin on substrate
carried by a build plate. The light energy can crosslink or
polymerize the silicone polymer. Unless otherwise indicated or made
clear from the context, it should be understood that steps 1602 and
1604 of the exemplary method 1600 are analogous to the
corresponding steps 1402 and 1404 of the exemplary method 1400
(FIG. 14).
[0201] As shown in step 1608, the exemplary method 1600 can
include, for each layer of a plurality of layers, repeating the
steps of providing the resin and directing light energy in a
predetermine pattern onto a given layer of a resin to form a
three-dimensional object.
[0202] As shown in step 1610, the exemplary method 1600 can include
thermally decomposing the crosslinked or polymerized silicone
polymer into a ceramic. In implementations in which the resin
includes particles of metal suspended in the silicone polymer, the
exemplary method 1600 can include thermally processing (e.g.,
sintering) particles of metal in the three-dimensional object
containing the ceramic. The ceramic can, for example, dissolve in
the metal or an alloy of the metal as the particles of the metal
are thermally processed. For example, the ceramic material can
include silicon carbide and the alloy of the metal can include
steel. Additionally, or alternatively, the exemplary method 1600
can include infiltrating a liquid metal into the ceramic material
in the three-dimensional object. The ceramic material in the metal
can be dissolved in the liquid metal or in an alloy of the metal of
the liquid metal.
[0203] While resins have been described as including particles of
different materials to facilitate light penetration through a layer
of the resin, other configurations are additionally or
alternatively possible. For example, referring now to FIG. 17, a
resin 1700 can include particles of a metal 1702 and a coating 1704
disposed on the particles of the metal 1702. The coating 1704 can
be formed of a material different from the particles of the metal
1702, and the coating 1704 can have an average thickness of greater
than about 3 percent and less than about 85 percent of an average
diameter of the particles of the metal. It should be appreciated
that a coating thickness in this range is substantially larger than
natural oxide coatings that form on metals.
[0204] The particles of the metal 1702 and the coating 1704 can be
suspended in a binder system 1706, which can include any one or
more of the binders described herein. The material of the coating
1704 can be substantially transparent to light of a wavelength
sufficient to crosslink, polymerize, or both, at least one portion
of the binder system 1706 (e.g., a wavelength of about 300 nm to
about 450 nm). Thus, it should be further understood that the
coating 1704 can facilitate penetration of light through a layer of
the resin including coated metal particles. An exemplary light path
1708 is shown passing through the resin 1700.
[0205] In general, the particles of the metal 1702 can be any of
the various different metals described herein. Thus, for example,
the particles of the metal 1702 can have an average size less than
the wavelength of the light sufficient to crosslink, polymerize, or
both, the at least one portion of the binder system 1706.
[0206] The material of the coating 1704 can include, for example, a
ceramic. In such instances, the at least one portion of the binder
system 1706 can be crosslinkable, polymerizable, or both, through
exposure to light of a wavelength below a band gap of the ceramic.
Further, or instead, the ceramic can include a metal oxide, which
can include one or more of iron oxide, silicon oxide, aluminum
oxide, zirconium oxide, and chromium oxide. Additionally, or
alternatively, the ceramic can include a metal nitride, such as one
or more nitrides of one or more respective metals selected from the
group VII or group VIII elements. Still further in addition or
further in the alternative, the ceramic can include a metal carbide
(e.g., silicon carbide).
[0207] In general, the material of the coating 1704 can include any
of the transparent materials described herein. Thus, for example,
the material of the coating 1704 can include an intermetallic, a
ternary oxide, or both. Further, or instead, the material of the
coating 1704 can be chemically convertible to a metal (e.g., the
metal of the particles). In certain implementations, the material
of the coating 1704 can include a metal oxide, and the material of
the coating 1704 can be chemically reducible to a metal (e.g., the
metal of the particles or a component of an alloy).
[0208] While various different methods of providing a resin to a
media source have been described, it should be appreciated the use
of other thin coating techniques is additionally or alternatively
possible. For example, known thin coating techniques such as one or
more of slot die, tape casting, silk screen, and the like can be
used to deposit thin layers of any one or more of the resins
described herein onto a substrate as part of a fabrication process
of a three-dimensional object.
[0209] While three-dimensional objects described herein have been
described as being formed from a single resin, it should be
appreciated that the devices, systems, and methods of the present
disclosure have been described in this way sake of clarity and
efficiency of explanation and, unless otherwise specified, any one
or more of the devices, systems, and methods described herein can
operate using more than one resin. Thus, more specifically, a
plurality of resins can be combined on-demand to impart desired
variations in aesthetic and/or physicochemical properties in a
three-dimensional object being formed. That is, the plurality of
resins can be combined to impart layer-by-layer variations along
the three-dimensional object and, additionally or alternatively,
can be combined to impart intralayer variations along the
three-dimensional object. For example, in instances in which
different colors are desirable in a finished part, resins with
particles of different colors (e.g., red, green, and blue) can be
combined on demand for a given layer or a given portion of a layer
of the three-dimensional object for high-resolution control over
the color of a finished part formed from the three-dimensional
object. As an additional or alternative example, in instances in
which different physicochemical properties are desirable in a
finished part, a plurality of resins with different types of
particles can be combined on-demand such that the aggregate
combination of the plurality of resins includes a distribution of
particles thermally processable to form the target variation in
physicochemical properties along a finished part formed from the
three-dimensional object.
[0210] In certain implementations, a resin can be provided on
demand to facilitate formation of an interface layer between one or
more support structures and the three-dimensional object being
formed. The interface layer can inhibit bonding of one or more
support structures to the three-dimensional object during thermal
processing and/or debinding, thus facilitating removal of the one
or more support structures during fabrication of a finished part.
That is, support structures can be usefully incorporated into the
three-dimensional object to reduce the likelihood of unintended
sagging or other distortion associated with certain structural
features. However, in instances in which such support structures
are not intended to form a portion of the finished part, one or
more resins can be selectively provided in all or a portion of a
given layer to form the interface layer.
[0211] The one or more resins can include one or more components
useful for inhibiting bonding of the one or more support structures
to the three-dimensional object and, in general, the one or more
components can inhibit bonding by imparting locally certain
physicochemical properties to the interface layer. For example,
material in the one or more of the resins forming the interface
layer can be dissolvable for removal with a solvent prior to
sintering the three-dimensional object. Additionally, or
alternatively, material in the one or more resins forming the
interface layer can have a shrinkage rate differing from a
shrinkage rate of one or more resins forming the three-dimensional
object away from the interface layer, with the difference in
shrinkage rates facilitating separation of the interface layer from
the three-dimensional object during sintering and/or debinding. As
still a further or alternative example, the particles in the one or
more resins forming the interface layer can include a ceramic
material while one or more resins forming the three-dimensional
object away from the interface layer can include metal. The ceramic
material in the interface layer can shrink less than the metal in
the three-dimensional object during thermal processing.
[0212] The above systems, devices, methods, processes, and the like
may be realized in hardware, software, or any combination of these
suitable for a particular application. The hardware may include a
general-purpose computer and/or dedicated computing device. This
includes realization in one or more microprocessors,
microcontrollers, embedded microcontrollers, programmable digital
signal processors or other programmable devices or processing
circuitry, along with internal and/or external memory. This may
also, or instead, include one or more application specific
integrated circuits, programmable gate arrays, programmable array
logic components, or any other device or devices that may be
configured to process electronic signals. It will further be
appreciated that a realization of the processes or devices
described above may include computer-executable code created using
a structured programming language such as C, an object oriented
programming language such as C++, or any other high-level or
low-level programming language (including assembly languages,
hardware description languages, and database programming languages
and technologies) that may be stored, compiled or interpreted to
run on one of the above devices, as well as heterogeneous
combinations of processors, processor architectures, or
combinations of different hardware and software. In another aspect,
the methods may be embodied in systems that perform the steps
thereof, and may be distributed across devices in a number of ways.
At the same time, processing may be distributed across devices such
as the various systems described above, or all of the functionality
may be integrated into a dedicated, standalone device or other
hardware. In another aspect, means for performing the steps
associated with the processes described above may include any of
the hardware and/or software described above. All such permutations
and combinations are intended to fall within the scope of the
present disclosure.
[0213] Embodiments disclosed herein may include computer program
products comprising computer-executable code or computer-usable
code that, when executing on one or more computing devices,
performs any and/or all of the steps thereof. The code may be
stored in a non-transitory fashion in a computer memory, which may
be a memory from which the program executes (such as random access
memory associated with a processor), or a storage device such as a
disk drive, flash memory or any other optical, electromagnetic,
magnetic, infrared or other device or combination of devices. In
another aspect, any of the systems and methods described above may
be embodied in any suitable transmission or propagation medium
carrying computer-executable code and/or any inputs or outputs from
same.
[0214] The method steps of the implementations described herein are
intended to include any suitable method of causing such method
steps to be performed, consistent with the patentability of the
following claims, unless a different meaning is expressly provided
or otherwise clear from the context. So, for example performing the
step of X includes any suitable method for causing another party
such as a remote user, a remote processing resource (e.g., a server
or cloud computer) or a machine to perform the step of X.
Similarly, performing steps X, Y and Z may include any method of
directing or controlling any combination of such other individuals
or resources to perform steps X, Y and Z to obtain the benefit of
such steps. Thus, method steps of the implementations described
herein are intended to include any suitable method of causing one
or more other parties or entities to perform the steps, consistent
with the patentability of the following claims, unless a different
meaning is expressly provided or otherwise clear from the context.
Such parties or entities need not be under the direction or control
of any other party or entity, and need not be located within a
particular jurisdiction.
[0215] It should further be appreciated that the methods above are
provided by way of example. Absent an explicit indication to the
contrary, the disclosed steps may be modified, supplemented,
omitted, and/or re-ordered without departing from the scope of this
disclosure.
[0216] It will be appreciated that the methods and systems
described above are set forth by way of example and not of
limitation. Numerous variations, additions, omissions, and other
modifications will be apparent to one of ordinary skill in the art.
In addition, the order or presentation of method steps in the
description and drawings above is not intended to require this
order of performing the recited steps unless a particular order is
expressly required or otherwise clear from the context. Thus, while
particular embodiments have been shown and described, it will be
apparent to those skilled in the art that various changes and
modifications in form and details may be made therein without
departing from the spirit and scope of this disclosure and are
intended to form a part of the invention as defined by the
following claims, which are to be interpreted in the broadest sense
allowable by law.
* * * * *