U.S. patent application number 09/818482 was filed with the patent office on 2001-11-29 for method of applying marking to metal sheet for scrap sorting purposes.
Invention is credited to Charles, David F., Courval, Greg J., Thomas, Michael P., Wheeler, Michael J., Wilson, Ian.
Application Number | 20010045378 09/818482 |
Document ID | / |
Family ID | 25225642 |
Filed Date | 2001-11-29 |
United States Patent
Application |
20010045378 |
Kind Code |
A1 |
Charles, David F. ; et
al. |
November 29, 2001 |
Method of applying marking to metal sheet for scrap sorting
purposes
Abstract
Application of surface marking to metal stock, such as aluminum
sheet, prior to or during scrap-generating manufacturing
operations, to provide a detectable mark on pieces of manufacturing
scrap derived from the marked sheet and commingled with scrap of
other aluminum alloy sheet, so that the scrap can be sorted and the
marked alloy scrap pieces separated from scrap of other alloy sheet
to which the marking was not applied. Different markings, providing
detectably different marks, may be respectively applied to sheet of
different compositions if scrap pieces of more than two different
compositions or compositional families are to be sorted and
separated from each other.
Inventors: |
Charles, David F.;
(Farmington Hills, MI) ; Courval, Greg J.;
(Napanee, CA) ; Thomas, Michael P.; (Farmington
Hills, MI) ; Wheeler, Michael J.; (Kingston, CA)
; Wilson, Ian; (Kingston, CA) |
Correspondence
Address: |
Christopher C. Dunham
c/o COOPER & DUNHAM LLP
1185 Avenue of the Americas
New York
NY
10036
US
|
Family ID: |
25225642 |
Appl. No.: |
09/818482 |
Filed: |
March 27, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09818482 |
Mar 27, 2001 |
|
|
|
09440485 |
Nov 15, 1999 |
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Current U.S.
Class: |
209/3.3 ; 209/3;
209/587 |
Current CPC
Class: |
Y02P 10/20 20151101;
B07C 2501/0036 20130101; C22B 7/005 20130101; C22B 7/00 20130101;
Y02P 10/212 20151101; B07C 5/3427 20130101; B21C 51/00 20130101;
B21C 51/005 20130101; C22B 21/0069 20130101; B07C 5/3412
20130101 |
Class at
Publication: |
209/3.3 ; 209/3;
209/587 |
International
Class: |
B07C 005/02 |
Claims
What is claimed is:
1. In a method of sorting metal scrap comprising a mixture of scrap
metal pieces respectively derived from metal stock of at least two
different compositions, to separate the scrap metal pieces of a
first of said compositions from the scrap metal pieces of a second
of said compositions, said stock of each of said two compositions
having a surface and being initially separate from the stock of the
other of said two compositions, said scrap being generated and
mixed during or after procedures performed on said stock of said
two compositions, and said scrap metal pieces of each of said two
compositions bearing portions of the surface of the stock from
which they are derived, the steps of (a) prior to or during the
performance of said procedures, while said metal stock of said
first composition is separate from the metal stock of said second
composition, selectively marking the surface of only the stock of
said first composition to provide a detectable surface mark on said
surface portions on said scrap metal pieces of said first
composition after the performance of said procedures, such that
said mark is present only on said scrap metal pieces of said first
composition in said mixture, and (b) scanning the mixture of metal
scrap to detect said mark on scrap metal pieces therein, and
thereby to distinguish said scrap metal pieces of said first
composition from other scrap metal pieces in said mixture.
2. A method according to claim 1, wherein said marking step is
performed by selectively applying a marking agent to the surface of
only the stock of said first composition in an amount effective to
provide said detectable surface mark on said surface portions on
said scrap metal pieces of said first composition after the
performance of said procedures.
3. A method according to claim 1, wherein said marking step is
performed prior to the performance of said procedures.
4. A method according to claim 3, wherein said marking step is
performed by selectively applying a marking agent to the surface of
only the stock of said first composition in an amount effective to
provide said detectable surface mark on said surface portions on
said scrap metal pieces of said first composition after the
performance of said procedures.
5. A method according to claim 4, further including a step of
segregating the scrap metal pieces on surface portions of which
said mark is detected upon detection of said mark thereon in said
scanning step.
6. A method according to claim 4, further including the step,
performed prior to the performance of said procedures and while
said metal stock of said first composition is separate from the
metal stock of said second composition, of selectively applying a
second marking agent to the surface of only the stock of said
second composition in an amount effective to provide a detectable
surface mark on said surface portions on said scrap metal pieces of
said second composition after the performance of said procedures,
such that said mark is present only on said scrap metal pieces of
said second composition in said mixture, the detectable surface
mark thus provided on said second-composition scrap metal pieces
being detectably different from the aforesaid mark provided on the
first-composition scrap metal pieces; and wherein the scanning step
comprises scanning the mixture of metal scrap to detect the surface
mark provided by the first-mentioned marking agent on the
first-composition scrap metal pieces and the surface mark provided
by said second marking agent on the second-composition scrap metal
pieces therein, thereby to distinguish said scrap metal pieces of
said first and second compositions from each other and from any
other scrap metal pieces in said mixture.
7. A method according to claim 4, wherein said metal stock is
prepared for said procedures by being subjected to at least one
preparatory step, and wherein said marking agent is applied to the
surface of the first-composition stock in said one preparatory
step.
8. A method according to claim 7, wherein said one preparatory step
is a surface treatment comprising applying a substance to the
surface of said first-composition stock, said method further
including the step of incorporating said marking agent in said
substance prior to application of said substance to the
first-composition stock surface.
9. A method according to claim 8, wherein the step of applying a
substance is selected from the group consisting of coating,
washing, etching, prelubricating and lubricating steps.
10. A method according to claim 4, wherein said metal stock of each
composition is aluminum sheet.
11. A method according to claim 10, wherein said first-composition
aluminum sheet consists of sheet of one or more aluminum alloy
compositions within a first family of alloys consisting of
specifically different compositions having at least one shared
compositional characteristic, and said second-composition aluminum
sheet consists of sheet of one or more aluminum alloy compositions
within a second family of alloys consisting of specifically
different compositions having at least one shared compositional
characteristic that differentiates the members of the second family
from the first family.
12. A method according to claim 11, wherein one of said first and
second families is the Aluminum Association 5000 series of
alloys.
13. A method according to claim 12, wherein the other of said first
and second families is the Aluminum Association 6000 series of
alloys.
14. A method according to claim 10, wherein said procedures are
operations for manufacturing articles from said aluminum sheet of
each of said compositions, said scrap is manufacturing scrap
generated incident to said manufacturing operations, said aluminum
sheet of said first and second compositions is prepared for said
manufacturing operations by being subjected to steps including at
least one surface treatment, and wherein said marking agent is
applied to the surface of the first-composition sheet in said one
surface treatment.
15. A method according to claim 14, wherein the surface treatment
step comprises applying a lubricant or prelubricant to said surface
of said aluminum sheet of said first composition in preparing the
sheet for the manufacturing operation, said method further
including incorporating said marking agent into said lubricant or
prelubricant before applying said lubricant to said sheet
surface.
16. A method of applying a marking agent to metal stock for scrap
sorting purposes, comprising (a) preparing metal stock of a first
composition for subjection to a manufacturing operation, said stock
having a surface, by subjecting said stock to at least one
preparatory step, while (b) applying to said stock surface, in said
one preparatory step, a marking agent in an amount effective to
provide a detectable surface mark on scrap metal pieces derived
from said stock during or after the manufacturing operation and
bearing portions of the stock surface, thereby to enable scrap
pieces of said stock to be distinguished from scrap pieces of stock
of other composition different from said first composition in a
mixture of scrap metal pieces of said first and other
compositions.
17. A method of applying a marking agent to metal stock for scrap
sorting purposes, comprising (a) preparing metal stock of a first
composition for subjection to a manufacturing operation, said
first-composition stock having a surface, by subjecting said stock
to at least one preparatory step, and (b) preparing metal stock of
a second composition for subjection to a manufacturing operation,
said second-composition stock having a surface, by subjecting said
second-composition stock to at least one preparatory step, while
(c) applying to said first-composition stock surface, in said one
preparatory step to which the first-composition stock is subjected,
a first marking agent in an amount effective to provide a
detectable surface mark on scrap metal pieces derived from said
first-composition stock during or after the manufacturing operation
and bearing portions of the first-composition stock surface, and
(d) applying to said second-composition stock surface, in said one
preparatory step to which the second-composition stock is
subjected, a second marking agent in an amount effective to provide
a detectable surface mark on scrap metal pieces derived from said
second-composition stock during or after the manufacturing
operation and bearing portions of the second-composition stock
surface, said last-mentioned surface mark being detectably
distinguishable from the aforesaid surface park provided on
first-composition scrap metal pieces, thereby to enable scrap
pieces of said first-composition stock and scrap pieces of said
second-composition stock to be distinguished from each other and
from scrap pieces of stock of any other composition in a mixture of
scrap metal pieces of said first and second compositions optionally
also including scrap metal pieces of other compositions.
18. A method of applying a marking agent to aluminum sheet for
scrap sorting purposes, comprising (a) preparing aluminum alloy
sheet of a first alloy composition for subjection to a
manufacturing operation, said sheet having a surface, while (b)
applying to said sheet surface, incident to preparing said sheet as
aforesaid, a marking agent in an amount effective to provide a
detectable surface mark on scrap metal pieces derived from said
sheet during or after the manufacturing operation and bearing
portions of the sheet surface, thereby to enable scrap pieces of
said sheet to be distinguished from scrap pieces of sheet of an
aluminum alloy of other composition different from said first
composition in a mixture of scrap metal pieces of said first and
other compositions.
19. A method according to claim 18, wherein said preparing step is
a surface treatment comprising applying a substance to the surface
of said first-composition sheet, said method further including the
step of incorporating said marking agent in said substance prior to
application of said substance to the first-composition sheet
surface.
20. A method according to claim 19, wherein the step of applying a
substance is selected from the group consisting of coating,
washing, etching, prelubricating and lubricating steps.
21. A method according to claim 20, wherein the step of applying a
substance is a lubricating or prelubricating step and the
incorporating step comprises incorporating said marking agent in a
lubricant or prelubricant for application in said lubricant or
prelubricant to said sheet in the lubricating step.
22. A method of preparing aluminum sheet for scrap sorting
purposes, comprising (a) preparing aluminum sheet of a first alloy
composition for subjection to a manufacturing operation, said
first-composition sheet having a surface, and (b) preparing
aluminum sheet of a second alloy composition different from said
first composition for subjection to a manufacturing operation, said
second-composition sheet having a surface, while (c) selectively
applying only to the surface of said first-composition sheet, and
not to the surface of the second-composition sheet, incident to
preparing said sheets as aforesaid, a marking agent in an amount
effective to provide a detectable mark on scrap metal pieces
derived from said first-composition sheet during or after the
manufacturing operation and bearing portions of the
first-composition sheet surface, thereby to enable scrap pieces of
said first-composition sheet to be distinguished by scanning from
scrap pieces of said second-composition sheet in a mixture of scrap
metal pieces of said first and second compositions.
23. A method according to claim 22, further including the step of
selectively applying only to the surface of said second-composition
sheet, and not to the surface of the first-composition sheet,
incident to preparing said sheets as aforesaid, a second marking
agent in an amount effective to provide a detectable mark on scrap
metal pieces derived from said second-composition sheet during or
after the manufacturing operation and bearing portions of the
second-composition sheet surface, the mark thereby provided on the
second-composition scrap pieces being distinguishable from the
aforesaid mark provided on scrap pieces of said first-composition
sheet.
24. A method according to claim 23, wherein the applying step
comprises incorporating said marking agent in a lubricant or
prelubricant and applying said lubricant or prelubricant containing
said marking agent to said first-composition sheet, and wherein any
lubricant or prelubricant applied in the step of preparing the
second-composition sheet is essentially free of said marking
agent.
25. A method according to claim 24, wherein said first-composition
sheet consists of sheets of one or more alloy compositions within a
first family of alloys consisting of specifically different
compositions having at least one shared compositional
characteristic, and said second-composition sheet consists of
sheets of one or more alloy compositions within a second family of
alloys consisting of specifically different compositions having at
least one shared compositional characteristic that differentiates
the members of the second family from the first family.
26. A method according to claim 25, wherein one of said first and
second families is the Aluminum Association 5000 series of
alloys.
27. A method according to claim 26, wherein the other of said first
and second families is the Aluminum Association 6000 series of
alloys.
28. A method of sorting metal scrap generated incident to
manufacturing operations performed on aluminum sheet of at least
two different alloy compositions, the sheet of each said
composition having a surface and the scrap comprising a mixture of
scrap metal pieces respectively derived from the aluminum sheet of
each of said compositions and bearing portions of the surface of
the sheet from which the pieces are derived, said method
comprising: (a) subjecting, to the manufacturing operations, sheet
of a first of said compositions bearing on its surface a marking
agent applied thereto, prior to the manufacturing operations, in an
amount effective to provide a detectable mark on said scrap metal
pieces derived from said first-composition sheet, and sheet of a
second of said compositions which is essentially free of said
marking agent; and (b) scanning the mixture of metal scrap to
detect said mark on scrap metal pieces therein, and thereby to
distinguish said scrap metal pieces of said first composition from
other scrap metal pieces in said mixture.
29. In a method of sorting metal scrap comprising a mixture of
scrap metal pieces respectively derived from metal stock of at
least two different compositions, to separate the scrap metal
pieces of a first of said compositions from the scrap metal pieces
of a second of said compositions, said stock of each of said two
compositions having a surface and being initially separate from the
stock of the other of said two compositions, said scrap being
generated and mixed during or after procedures performed on said
stock of said two compositions to produce articles bearing first
portions of the surface of the stock from which they are made and
to detach said scrap from said articles, and said scrap metal
pieces of each of said two compositions bearing second portions of
the surface of the stock from which they are derived, the steps of
(a) prior to or during the performance of said procedures, while
said metal stock of said first composition is separate from the
metal stock of said second composition, selectively marking only
said second portions of the surface of the stock of the first
composition to provide a detectable surface mark thereon after the
performance of said procedures, such that said mark is present only
on said scrap metal pieces of said first composition in said
mixture, and (b) scanning the mixture of metal scrap to detect said
mark on scrap metal pieces therein, and thereby to distinguish said
scrap metal pieces of said first composition from other scrap metal
pieces in said mixture.
30. A method according to claim 29, wherein said mark is an
indelible mark.
31. A method according to claim 30, wherein the marking step
comprises applying an indelible marking agent to said second
surface portions.
32. A method according to claim 30, wherein the marking step
comprises locally deforming at least one area of each said second
surface portion.
33. A method according to claim 30, wherein the marking step is
performed prior to the performance of said procedures.
34. A method according to claim 30, wherein the marking step is
performed substantially concurrently with the performance of said
procedures.
35. A method according to claim 30, wherein said stock of said
first composition is provided as a strip, wherein said procedures
include a blanking operation for cutting the strip into discrete
sheet pieces and a stamping operation performed on said sheet
pieces to form said articles and to detach said scrap therefrom,
and wherein said marking step is performed on said sheet pieces
incident to said blanking operation.
36. A method according to claim 30, further including the steps of:
prior to or during the performance of said procedures, while said
metal stock of said first composition is separate from the metal
stock of said second composition, selectively marking only the
second portions of the surface of the stock of the second
composition to provide a second detectable surface mark on said
second surface portions on said scrap metal pieces of said second
composition after the performance of said procedures, such that
said second detectable surface mark is present only on said scrap
metal pieces of said second composition in said mixture, said
second detectable surface mark being distinguishable from the
first-mentioned detectable surface mark on the scrap metal pieces
of the first composition.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of applicants'
copending U.S. patent application Ser. No. 09/440,485, filed Nov.
15, 1999, the entire disclosure of which is incorporated herein by
this reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates to the sorting of metal scrap
constituted of a mixture of scrap metal pieces of two or more
different alloy compositions, so as to separate the metal pieces of
one composition from the other or others. More particularly, it is
directed to methods of marking aluminum sheet for scrap sorting
purposes.
[0003] As used herein, the term "aluminum" refers to aluminum metal
and aluminum-based alloys, viz., alloys containing more than 50% by
weight aluminum. "Scrap" refers to pieces of metal in solid as
distinguished from molten state.
[0004] An important and illustrative field of use for such methods
(to which, however, the invention in its broader aspects is not
limited) is the sorting of manufacturing scrap generated incident
to automobile manufacturing operations utilizing aluminum sheet.
The production of automobile body components or other automotive
parts by forming aluminum sheet generates substantial quantities of
metal scrap, i.e., pieces of metal from the sheet stock subjected
to the forming and related operations such as trimming. The term
"manufacturing scrap" is used herein to differentiate such scrap
from post-consumer scrap (generated from used and discarded
manufactured articles). Manufacturing scrap differs from
post-consumer scrap in that, being generated incident to forming
operations, manufacturing scrap does not bear a paint or other
permanent opaque coating on its major surfaces, whereas
post-consumer scrap often has major surfaces more or less covered
with paint or other substances applied after forming.
[0005] As is well known, for both environmental and economic
reasons it is desirable to recycle sheet metal scrap, including
that generated in the manufacture of automotive components from
sheet aluminum. In the simplest sense, recycling of the scrap
involves remelting the scrap to provide a body of molten metal that
can be cast and rolled into useful aluminum sheet.
[0006] Frequently, however, automotive manufacturing scrap includes
a mixture of scrap pieces of two or more aluminum alloys differing
substantially from each other in composition. A specific example of
mixed manufacturing scrap of aluminum sheet, generated in certain
present-day automotive manufacturing operations, is a mixture of
pieces of one or more alloys of the Aluminum Association 5000
series (with four-digit registration numbers between 5000 and 5999)
and pieces of one or more alloys of the Aluminum Association 6000
series (with four-digit registration numbers between 6000 and
6999).
[0007] The presence of commingled pieces of different alloys in a
body of scrap limits the ability of the scrap to be usefully
recycled, unless the different alloys (or, at least, alloys
belonging to different compositional families such as those
respectively designated by the Aluminum Association series 1000,
2000, 3000, etc.) can be separated prior to remelting. This is
because, when commingled scrap of plural different alloy
compositions or composition families is remelted, the resultant
molten mixture contains proportions of principal alloying elements
(of the different compositions) that are too high to satisfy the
compositional limitations of any particular commercial alloy. While
it would therefore be beneficial to be able to sort a mass or body
of aluminum sheet scrap containing a mixture of pieces of different
alloys, to separate the different alloy compositions or at least
different alloy families before remelting for recycling, scrap
pieces of different aluminum alloy compositions are not ordinarily
visually distinguishable from each other.
[0008] Published European Patent Application EP 0 861 910 A2
describes procedures for treating commingled aluminum scrap of two
or more wrought aluminum alloys to impart different colors to
surfaces of scrap pieces of different compositions for the purpose
of sorting by alloy type or family (such as Aluminum Association
series). The described procedures involve a separate step for
introducing color onto the alloy before sorting, but after the
alloy pieces of different compositions have become commingled, via
a batch or semi-continuous chemical etch or series of etches. The
chemical agents react with alloys of different compositions to
produce discernable surface color differences between them. Methods
for introducing color proposed include treatment with caustic,
acid, oxidizing agents, dyes and combinations thereof.
[0009] That is to say, in the process of the European patent
application, the marker is applied to every piece of scrap by a
chemical treatment process and is subsequently detected by color
differentiation. Treating every piece of scrap is inherently an
expensive process, involving the performance of special, extra
steps after the scrap is collected and before it can be sorted; and
since the sortability of the commingled scrap is dependent on the
ability of the treatment to react with different alloys to produce
discernably different, composition-determined colors, there are
limits to the coloring agents that can be used and/or to the types
of alloys that can be differentiated.
SUMMARY OF THE INVENTION
[0010] An object of the present invention is to provide
improvements in the sorting of metal scrap containing scrap pieces
of different compositions, affording enhanced convenience and
economy. Another particular object is to provide such improvements
while avoiding a separate or special step of marking the scrap
(i.e., after the scrap has been generated) to differentiate pieces
of different compositions for such sorting. A specific object is to
provide improved methods, affording the advantages just stated, of
marking aluminum sheet to facilitate subsequent sorting of scrap
including scrap pieces derived from the sheet together with scrap
pieces of sheet of other aluminum alloys or alloy families.
[0011] To these and other ends, the invention embraces the
application of surface marking to metal stock (i.e., metal produced
or prepared in a form for working, cutting, etc., to manufacture
articles or components), particularly aluminum sheet, prior to or
during the performance of scrap-generating operations such as
manufacturing operations.
[0012] In certain embodiments of the invention, the marking is
performed by application of a marking agent to the stock or sheet
during and as a part of procedures for preparing the sheet or other
stock for subsequent scrap-generating manufacturing operations. For
example, in preparing aluminum sheet for forming into automotive
components or the like, it is conventional for the maker and
supplier of the sheet to apply lubricant or prelubricant to
surfaces of the sheet; in accordance with the present invention,
the marking agent may be incorporated in the lubricant or
prelubricant prior to application thereof to the sheet
surfaces.
[0013] It is found that this method, utilizing a conventional
sheet-preparing step for applying the marking agent and thereby
avoiding any separate or added treatment of either sheet or scrap,
can provide a detectable mark on surfaces of manufacturing scrap
derived from the marked sheet, the marking agent being initially
applied to the sheet in an amount effective to establish a deposit
of mark-providing substance that will survive the scrap-generating
manufacturing operations to which the sheet is subjected.
[0014] The term "mark" as used herein is not limited to a deposit
of marking agent which is visible or discernable as a mark on the
original sheet; i.e., the marking agent provides a detectable mark
on the scrap, not necessarily a visible mark on the sheet.
Moreover, while in many instances detection of the mark may be
performed by optical scanning, the detectable mark on scrap
surfaces contemplated by the invention in its broadest aspects is
not limited to a mark that is optically detectable, but also
broadly includes a mark that is or can be detected in non-optical
ways, e.g. by a sniffing device as used to detect drugs at
airports, or by a laser that evaporates surface material in a puff
or plume with a short pulse, with immediate analysis of the plume
to identify the "mark" substance.
[0015] The sheet to which the marking agent is applied may be of a
single specific alloy composition, or may include sheet of two or
more specific compositions within a compositional family (such as
an Aluminum Association series, e.g., 1000, 2000, 3000, etc.) of
which the members are sufficiently close in composition so that
remelting of their commingled scrap provides a readily usable metal
product. In the case where the manufacturing operations are such as
to employ aluminum sheet of two composition families, generating
scrap derived from sheet of both families, the marking agent is
applied only to the sheet of one family, and not to the sheet of
the other family, prior to the manufacturing operations. The
residual optically detectable mark that thereby results, being
present only on the surfaces of scrap pieces derived from sheet of
the aforesaid one compositional family, enables easy sorting and
separation of the pieces of the scrap into their respective
compositional families, for remelting and recycling. Alternatively,
different marking agents (respectively providing detectably
different marks on scrap surfaces) may be applied to sheet of
different alloy compositions or composition families, facilitating
the sorting of scrap including scrap pieces of more than two
compositions or families which are to be separated from each
other.
[0016] Stated in some respects more broadly, the present invention
concerns improvements in sorting metal scrap comprising a mixture
of scrap metal pieces respectively derived from metal stock of at
least two different compositions (e.g., at least two different
compositional families), to separate the scrap metal pieces of a
first of the compositions from the scrap metal pieces of a second
of the compositions, the stock of each of the two compositions
having a surface and being initially separate from the stock of the
other of the two compositions, the scrap being generated and mixed
during or after procedures performed on the stock of the two
compositions, and the scrap metal pieces of each of the two
compositions bearing visible portions of the surface of the stock
from which they are derived. In this broad sense, the method of the
invention embraces the steps of selectively applying a marking
agent to the surface of only the stock of the first composition,
prior to the performance of the aforesaid procedures, while the
first-composition metal stock is separate from the metal stock of
the second composition, the marking agent being applied in an
amount effective to provide a detectable surface mark on surface
portions on the scrap metal pieces of the first composition after
the performance of the aforesaid procedures, such that the mark is
present only on the scrap metal pieces of the first composition in
the mixture, and scanning the mixture of metal scrap to detect the
mark on scrap metal pieces therein, and thereby to distinguish the
scrap metal pieces of the first composition from other scrap metal
pieces in the mixture. Such a method typically further includes a
step of segregating the scrap metal pieces on surface portions of
which the mark is detected upon detection of said mark thereon in
the scanning step.
[0017] The term "scanning" herein embraces ordinary visual scrutiny
of the scrap with the human eye, in instances where the mark is
discernable at visible wavelengths of light, with manual separation
of scrap pieces, as well as scanning with apparatus e.g. of types
currently commercially available and which may be capable of
viewing the surfaces of the scrap pieces at ultraviolet, visible,
or infrared wavelengths and mechanically sorting the scrap pieces
in accordance with the presence or absence of a detected mark
thereon. In addition, the term "scanning" is not limited to optical
scanning but also includes non-optical scanning of the strip, e.g.
by a sniffing device or a device that evaporates surface material
and analyzes the resulting vapor plume to identify the mark
substance, as mentioned above. In convenient embodiments, to which
however the invention is not limited, the mark is a color,
detectably present on visible surface portions on the
first-composition scrap metal pieces, that is detectably different
from the color of the unmarked second-composition scrap metal
pieces.
[0018] The invention in this broad sense is applicable to the
sorting of scrap of any metal, including (by way of example),
steel, copper and magnesium alloys.
[0019] In an important particular aspect, the invention
contemplates the provision of a method of applying a marking agent
to aluminum sheet for scrap sorting purposes, comprising preparing
aluminum alloy sheet of a first alloy composition for subjection to
a manufacturing operation, the sheet having a surface, while
applying to the sheet surface, incident to preparing the sheet as
aforesaid, a marking agent in an amount effective to provide a
detectable surface mark on scrap metal pieces derived from the
sheet during or after the manufacturing operation and bearing
visible portions of the sheet surface, thereby to enable scrap
pieces of the sheet to be distinguished from scrap pieces of sheet
of an aluminum alloy of other composition different from the first
composition in a mixture of scrap metal pieces of the first and
other compositions. Conveniently, the preparing step may be a
surface treatment (e.g., a coating, washing, etching,
prelubricating or lubricating step) which comprises applying a
substance to the surface of the first-composition sheet, the method
further including the step of incorporating the marking agent in
the substance prior to application of the substance to the
first-composition sheet surface. In specific embodiments, the
applying step comprises incorporating the marking agent in a
lubricant or prelubricant and applying the lubricant or
prelubricant containing the marking agent to the sheet.
[0020] Where sheet of alloys of two different compositions (e.g.
sheet of two different families of compositions) is being produced
and prepared for manufacturing operations which will generate scrap
comprising scrap metal pieces of both compositions, the method in
particular embodiments includes preparing aluminum sheet of the
first alloy composition for subjection to a manufacturing
operation, and preparing aluminum sheet of a second alloy
composition different from the first composition for subjection to
a manufacturing operation, the second-composition sheet also having
a surface, while selectively applying only to the surface of the
first-composition sheet, and not to the surface of the
second-composition sheet, incident to preparing the sheets as
aforesaid, a marking agent in an amount effective to provide a
detectable mark on scrap metal pieces derived from the
first-composition sheet during or after the manufacturing operation
and bearing portions of the first-composition sheet surface,
thereby to enable scrap pieces of the first-composition sheet to be
distinguished by scanning from scrap pieces of the
second-composition sheet in a mixture of scrap metal pieces of the
first and second compositions. Thus, where the applying step
comprises incorporating the marking agent in a lubricant or
prelubricant applied to the first-composition sheet, any lubricant
or prelubricant applied in the step of preparing the
second-composition sheet is essentially free of the marking
agent.
[0021] In some instances, a different marking agent (providing a
mark detectably different from that of the first-mentioned marking
agent) may be applied to the second-composition sheet, for example
by incorporating the second marking agent in a lubricant or
prelubricant applied to the second-composition sheet surface prior
to the manufacturing operations. This can be useful if the scrap
contains more than two different compositions each of which is to
be segregated from the others. In the case where the scrap is to be
sorted into only two compositions (or composition families),
however, it is convenient and economically beneficial to use only
one marking agent, applied to sheet of only one of the compositions
or composition families and providing a mark that, on the scrap
pieces, enables the marked scrap pieces to be distinguished
optically from unmarked scrap pieces. Thereby, the use of a second
marking agent and the step of incorporating such a second agent in
the lubricant for second-composition sheet are avoided.
[0022] In particular embodiments of current commercial interest,
e.g. in the manufacture of automotive components, the
first-composition sheet consists of sheets of one or more alloy
compositions within a first family of alloys consisting of
specifically different compositions having at least one shared
compositional characteristic, and the second-composition sheet
consists of sheets of one or more alloy compositions within a
second family of alloys consisting of specifically different
compositions having at least one shared compositional
characteristic that differentiates the members of the second family
from the first family. Illustratively, these families may
respectively be the Aluminum Association 5000 and 6000 alloy
series.
[0023] In another aspect, the invention embraces a method of
sorting metal scrap generated incident to manufacturing operations
performed on aluminum sheet of at least two different alloy
compositions, the sheet of each composition having a surface and
the scrap comprising a mixture of scrap metal pieces respectively
derived from the aluminum sheet of each of the compositions and
bearing visible portions of the surface of the sheet from which the
pieces are derived, the method comprising subjecting, to the
manufacturing operations, sheet of a first of the compositions
bearing on its surface a marking agent applied thereto, prior to
the manufacturing operations, in an amount effective to provide a
detectable mark on the scrap metal pieces derived from the
first-composition sheet, and sheet of a second of the compositions
which is essentially free of the marking agent; and scanning the
mixture of metal scrap to detect the mark on scrap metal pieces
therein, thereby to distinguish the first-composition scrap metal
pieces from other scrap metal pieces.
[0024] Embodiments of the invention such as those involving the
addition of a fluorescent tracer-type marking agent to a lubricant
or prelubricant conventionally supplied to the sheet by the sheet
producer prior to delivery to a manufacturing customer, sometimes
present a drawback in that the tracer-containing lubricant may be
removed and/or transferred to scrap pieces of different composition
(not initially bearing the tracer) incident to manufacturing
procedures or subsequent handling and commingling of the scrap.
When the marking agent is thus removed or transferred, the ability
to distinguish between scrap of different compositions in the
scanning step can be impaired or lost.
[0025] Accordingly, as a still further feature of the invention, in
important preferred embodiments thereof, the step of selectively
marking the stock surface of metal stock of only the first
composition comprises applying a detectable marking to only those
surface portions of the first-composition stock which will become
surface portions of the scrap generated in the manufacturing
procedure performed on the stock. Stated with reference to stamping
operations for producing an article from stock and detaching scrap
portions of the stock from the article, in these embodiments the
marking is applied only to surface portions of the
first-composition stock that will be detached as scrap and not to
areas that will be included in the produced article.
[0026] This selective application of the marking only to areas of
the stock that will be scrapped enables application of an indelible
marking without compromising desired surface qualities or
characteristics of the produced article. By "indelible" is meant,
in this sense, any mark that is not substantially removable from
the stock or scrap surface, or transferrable to other surfaces
(such as surfaces of scrap of different composition), in the
manufacturing and subsequent scrap handling and commingling
procedures to which the marked stock and scrap are subjected. A
variety of paints and inks are suitably "indelible" for application
in such embodiments of the invention. More broadly, the indelible
marking need not be an applied marking agent but can take the form
of a detectable surface deformity such as an embossment applied,
e.g. concurrently with a blanking operation or in some instances a
stamping operation for producing an article, to areas of stock that
are to be scrapped.
[0027] Thus, in such preferred embodiments the method of the
invention contemplates selectively marking only surface portions,
of stock of one composition, that will not be included in an
article produced (by a stamping or other operation) from the stock,
to establish on those selectively marked surface portions an
indelible and detectable mark enabling scrap of the stock to be
distinguished from unmarked scrap of other composition by a
scanning step.
[0028] Further features and advantages of the invention will be
apparent from the detailed description hereinafter set forth,
together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a graph representing detected luminescence of a
fluorescent mark on an aluminum sheet surface as a function of
distance from the detecting scanner and doping level of fluorescent
marking agent in lubricant applied to the sheet surface, in the
tests described in EXAMPLE 1 below;
[0030] FIG. 2 is a graph representing detected luminescence of a
fluorescent mark on an aluminum sheet surface as a function of
distance from the detecting scanner and doping level of fluorescent
marking agent in lubricant applied to the sheet surface, after
partial removal of the lubricant, in the tests described in EXAMPLE
2 below; and
[0031] FIG. 3 is a graph representing detected luminescence of a
fluorescent mark on an aluminum sheet surface as a function of
distance from the detecting scanner for sheet surfaces bearing
undoped ("as-is") lubricant and lubricant doped with a fluorescent
tracer, using various colored filters, in the tests described in
EXAMPLE 3 below.
DETAILED DESCRIPTION
[0032] The invention will initially be described, for purposes of
illustration, as embodied in methods of applying a marking agent to
aluminum sheet to provide, on pieces of scrap derived from the
sheet, optically detectable surface marks for scrap sorting
purposes, and to scrap-sorting methods including such marking
procedures. It is to be understood, however, that the invention in
its broader aspects is not limited to the sorting of scrap derived
from aluminum sheet, but is applicable to other metal stock as
well, e.g., to sheet or other stock of steel, copper or magnesium
alloys, and to the provision of marks, on scrap pieces, which are
detectable in other than optical ways.
[0033] In the embodiments now to be described, the invention
involves pre-applying a marking agent to the surface of aluminum
sheet as part of the routine finishing process in the rolling mill
in which the final-gauge sheet is produced, i.e., as part of one of
the operations, such as cleaning, pretreatment, or the application
of a lubricant or prelubricant, routinely performed on such sheet
products before delivery to a manufacturing customer. Examples of
marking agents are visible dyes and pigments, fluorescent dyes,
compounds having distinctive infrared absorption spectra, and
photosensitive materials. Two ways of delivering these compounds to
the sheet surface are as part of a pretreatment regime or as an
additive to the lubricant or prelubricant applied to the sheet. A
pretreatment is anything which permanently changes the surface
characteristics of the sheet, such as anodizing, etching or
conversion coating. A lubricant is nonpermanent, the surface
remaining essentially unchanged once the lubricant is removed. A
prelubricant is a thin film of, e.g., mineral oil, over which an
automobile manufacturer applies the actual forming lubricant. The
lubricant or prelubricant route is currently preferred for the
present invention.
[0034] In the preferred embodiment, for use where sheets of two
aluminum alloy families (e.g., the 5000 series and the 6000 series)
contribute to manufacturing scrap, only the sheet from one of the
two alloy families is marked; the other remains unmarked. This
allows the automotive manufacturer to easily separate the scrap
from its stamping operations into the two original alloy families
for recycling purposes by using mechanical sorting equipment which
is under the control of a detection instrument sensitive to the
marking compound.
[0035] The invention, in its embodiments now to be described,
involves the use of an agent applied to the surface of one or more
aluminum sheet alloys to distinguish the alloy from other alloys,
and provides a method for applying such agent to the surface of
aluminum alloy sheet during production or finishing to result in a
treated alloy sheet, that enables subsequent sorting of treated
alloys from a mixture of treated and non-treated alloys.
[0036] The invention, in these embodiments, concerns the treatment
of the surface of one or more aluminum sheet alloys (particularly
automotive alloys) as an intrinsic part of the existing
manufacturing route to allow the alloys to be distinguished from
nontreated alloys in a subsequent sorting operation. Treated alloys
may be separated from unmarked alloys using a known color sorting
identification and mechanical sorting procedure and equipment, for
example that of Huron Valley Steel Corporation of Belleville,
Mich.
[0037] The treatment can be in the form of coloring agent, a
fluorescent dye or a photosensitive material added during or after
cleaning (if a cleaning step is present), in the lubricant or
prelubricant applied to the sheet or possibly in the pretreatment
(the latter for structural alloys only). Whichever method is used,
the treatment must be sufficiently robust to allow the alloys to be
distinguished after the sheet has been processed through customer
stamping operations involving the application of stamping
lubricants and material handling.
[0038] Methods envisaged for effecting the treatment include roll
or brush application, spray or electrostatic deposition, or
immersion.
[0039] The present invention differs from the procedure of European
Patent Application EP 0 861 910 A2 by treating the surface of the
sheet product as part of the existing sheet manufacturing and
finishing route to produce a treated alloy sheet. The treated sheet
product is supplied to the customer and scrap generated during the
customer's operations is then capable of being sorted. The surface
treatment is designed so as not to degrade the customers' product
specifications.
[0040] Differentiation between 5000 and 6000 series alloys, for
example, for scrap sorting purposes can be made by marking the
surface of the scrap in some manner. This marker can then be
detected by an optical scanner. In previous work, as represented by
the aforementioned European Patent Application, the marker is
applied to each piece of scrap by a chemical treatment process and
is subsequently detected by color differentiation. In the method of
the present invention, the marker is applied to the sheet of the
selected series of alloys in the form of an additive to the
prelubricant or stamping lubricant. Lubricant or prelubricant is
applied in any case to sheet, so the additional cost of applying
lubricant or prelubricant with a marker is minimal. Sheet of one
series of alloys would have prelubricant or stamping lubricant with
marker and another series would have prelubricant or stamping
lubricant without marker.
[0041] The marker, or additive to the stamping lubricant or
prelubricant, can be selected from a number of classes of chemical
compounds. The detection process for the marker will then depend
upon the type of chemical selected. For example:
[0042] 1. The marker can be in the form of a soluble organic dye
which, when dissolved in the stamping fluid, changes the color of
the stamping fluid. Scrap could then be sorted by differentiating
between the different colors using a portable color detection
device, available from companies such as Byk-Gardner.
[0043] 2. The marker can also be in the form of a dispersible
organic or inorganic dye or pigment. These compounds would also
change the color of the stamping lubricant when dispersed therein.
The detection process would then be similar to that of (1)
above.
[0044] 3. The marker can be an organic compound which has
characteristic infrared absorption frequencies different from the
stamping lubricant. Lubricant containing this marker can then be
detected using a portable infrared scanner supplied by companies
such as Nicolet.
[0045] 4. The marker can be a fluorescing compound. Lubricant
containing this compound exhibits a level of luminescence different
from that of lubricant without the fluorescing compound when
scanned with a fluorescence scanner such as the LUT 1-4 available
from Sick Optics.
[0046] 5. The marker can be a photosensitive material, defined as a
compound that will undergo some permanent and detectable change in
response to being irradiated by a particular part of the
electromagnetic spectrum. In such case, the mark established by the
photosensitive marking agent would be latent unless and until scrap
pieces of the marked sheet surface are scanned, for sorting, by a
scanner emitting light in the activating portion of the
spectrum.
[0047] In an exemplary embodiment, in which a producer of aluminum
sheet supplies both sheet of 6000 series alloys and sheet of 5000
series alloys for automotive forming operations (customer stamping
operations) that generate scrap of both alloy families, to enable
sorting and separation of scrap of the two families, the
preparation of the sheet of both families includes application of a
conventional lubricant, such as that commercially designated
"MP404" lubricant, to the sheet surfaces. The MP404 lubricant is
applied without additive to the sheet of 6000 series alloys and
MP404 lubricant with an added fluorescent tracer is applied to the
sheet of 5000 alloys. These lubricant applications can be performed
on a continuous coating line. After performance of manufacturing
operations by the customer and generation of scrap of both alloy
families therein from the supplied sheet, the scrap, commingled, is
delivered to a recycling facility. At the recycling facility,
separation of alloys is effected using a luminescence scanner to
determine whether each scanned piece of scrap came from a sheet
bearing lubricant with tracer or without.
[0048] In the embodiments thus far described, a lubricant,
prelubricant or other vehicle containing a marking agent is
typically applied to an entire surface of stock prior to the
performance of procedures on the stock such as blanking and
stamping operations for producing articles therefrom; and, as
mentioned, such application may conveniently be performed by the
supplier of the stock to a manufacturer. It will be understood that
the stock is usually supplied as coiled strip, from which the
manufacturer, in a blanking operation, cuts successive discrete
pieces or sheets of appropriate shape and size for subjection to a
particular stamping operation, i.e., to produce by stamping, from
successive sheets, successive articles of identical dimensions and
configuration, with scrap portions of the discrete sheets being
detached from the article incident to the stamping operation.
[0049] For a given discrete cut sheet piece (formed in the blanking
operation), which is to be subjected to stamping in a particular
orientation to produce an article of given dimensions and
configuration, the locations of the surface areas of the sheet
piece which will be included in the produced article, and those
which will not be so included (i.e., will become surfaces of the
scrap) are fully determinable. Thus, as an alternative to
precoating entire stock surfaces with a vehicle containing a
marking agent, it is practicable for the manufacturer to perform
the marking step of the method of the invention by selectively
applying marks only in those surface areas of discrete cut pieces
of sheets (of the stock of the composition to be identified by
marking) that will not be included in a produced article.
[0050] Advantageously, an indelible mark is applied in these
embodiments of the invention, so that the markings will not be
removed (or transferred to surfaces of scrap of other composition)
prior to the scanning step in which the mark serves to distinguish
the marked scrap of one composition from unmarked (or differently
marked) scrap of other composition. The indelible marking agent may
be an indelible paint or ink, or a surface modification such as an
embossment or other local but detectable deformation. It may be
applied prior to or concurrently with performance of a blanking or
stamping operation. If the sheet stock bears pre-applied lubricant,
it is not necessary to remove the lubricant for application of the
indelible marks.
[0051] More particularly, the marks may conveniently or preferably
be applied in the blanking operation, in which straight-sided sheet
pieces, having an outline that very roughly approximates the part
or article to be produced by stamping, are formed by cutting the
sheet stock. These cut pieces include portions that will become
scrap when the stamping operation is performed, as well as a
portion that will become the article produced in the stamping
operation. After blanking, the cut sheet pieces are stacked and
delivered to the stamping operation where the article is
produced.
[0052] In the blanking plant, a computer has a stored outline of
the part or article which will subsequently be produced by
stamping. For performing the method of the present invention, a
movable marking head may be attached to the blanking machine, and
the computer may be programmed with instructions to guide the head
to apply the marks to the desired locations on the sheet surface,
i.e., at portions which will become scrap in the stamping
operation. As an alternative, a computer-controlled movable head
for marking such portions can be provided at the stamping operation
itself.
[0053] Some scrap may be generated in the blanking operation, but
blanking plants typically handle such scrap in ways that do not
involve commingling of scrap of different compositions, and
therefore scrap generated by blanking ordinarily does not require
marking in accordance with the invention. The greatest use of the
invention is for marking scrap generated in stamping
operations.
[0054] The applied marking need not cover all or even most of the
surface area of the scrap bearing the mark; it is sufficient that
the mark be visibly or otherwise detectably present, for detection
by scanning, somewhere on a surface of each piece of scrap. To this
end, marks may be applied to both surfaces of those sheet portions
that will become scrap, thereby insuring that each scrap piece will
bear at least one detectable mark even if the scrap becomes bent or
deformed.
[0055] Although the indelibly marked scrap may be passed through a
decoater if desired after sorting, it is generally not necessary to
remove the indelible marks applied in accordance with this
embodiment of the invention because the individual marks are small
in relation to the surface area of the scrap. It is sufficient, for
the attainment of the results and advantages of the invention, to
apply enough such small marks to ensure that each piece of scrap
(of sheet of the composition being marked) will have at least one
detectable surface mark.
[0056] The selective marking of only surface areas of stock that
will not be included in an article manufactured from the stock
enables the use of marks of an indelible character that would be
undesirable if present on the produced article. Thereby, the
desired assured durability and nontransferability of the marking,
required to distinguish scrap of different compositions by
scanning, can be achieved with no derogation from article
quality.
[0057] As in other embodiments of the invention, detectable marks
may be applied only to non-article surface areas of stock of one
composition, or detectably different marks may respectively be
applied to non-article surface areas of stock of different
compositions which are to be distinguished from each other.
[0058] By way of further illustration of the invention, reference
may be made to the following specific examples, in conjunction with
the drawings.
EXAMPLE 1
[0059] FIG. 1 summarizes initial experiments on the use of
luminescence as a means of separating automotive sheet for
recycling. "MP404" lubricant, with and without fluorescent tracer
added (and with various levels of fluorescent tracer addition or
doping in the tracer-added specimens) was applied to aluminum sheet
surfaces, and the lubricant-bearing surfaces were scanned to
measure luminescence at various surface-to-scanner distances.
[0060] The lubricant was applied to the sheet (in this and the
following Examples) with a draw-down bar set to deliver a nominal
level of 125 mg/ft.sup.2. Where the lubricant was doped with the
fluorescent dye (tracer), the lubricant was first heated to
70.degree. C., the required amount of dye was added, and the
mixture was then stirred until it was homogeneous.
[0061] The luminescence scanner employed was a LUT 1-4, made by
Sick Optics. Its basic principle of operation is simple: the
scanner emits ultraviolet light, then measures the luminescence in
the visible range given off by the object being scanned. The
fluorescent tracer or probe (i.e., marking agent) employed in these
tests was Fluor Yellow 131sc, made by Morton Thiokol, which was
selected particularly for its non-carcinogenic quality (many
fluorescent species are carcinogens). A baseline was obtained by
measuring the luminescence from sheet coated with standard
(undoped) MP404 lubricant at a nominal coating weight of 125
mg/ft.sup.2 at various distances from the sheet surface. As
expected, there is a small amount of fluorescence from the undoped
MP404 lubricant. The MP404 was then doped with the FY 131sc tracer
at levels up to 2,000 ppm. The level of luminescence increased
greatly, as shown in FIG. 1.
[0062] The effects of distance from the sheet surface and
concentration of tracer provide a preliminary estimation of the
ability of the system to measure small amounts of fluorescence
quantitatively. obviously there will be much less than 125
mg/ft.sup.2 on the scrap by the time it reaches the recycling
facility, especially if a blank washer is used before the sheet
goes into the stamping press. It is desirable not to use any more
tracer than needed, to keep the cost down.
[0063] The results graphically shown in FIG. 1 are set forth in
TABLE 1 below:
1TABLE 1 Distance from Source (inches) MP404 as-is 500 ppm FY 1000
ppm FY 2000 ppm FY 5 9 21 31 53 7 8 19 28 48 9 7 16 24 41 11 5 12
19 33 13 4 9 15 26 15 2 7 11 20
[0064] In summary, these tests demonstrated that the difference in
luminescence between MP404 lubricant doped with 500 to 2,000 ppm
fluorescent tracer and the same lubricant without tracer could
readily be detected at distances up to about 15 inches between the
sample and the scanner. The work also showed that the MP404
lubricant alone also fluoresced to a certain extent.
EXAMPLE 2
[0065] A further group of tests were performed to clarify the
detection limit of fluorescent tracer since in practice much of the
lubricant may be lost by the time scrap pieces reach the recycling
facility. To approximate this effect, samples with an initial
lubricant level of 125 mg/ft.sup.2, doped with indicated levels of
the same fluorescent tracer as in Example 1 or undoped, were wiped
down with tissue to remove most of the lubricant. It was very
difficult to obtain an accurate measure of the amount of residual
lubricant; the experimenters' estimate is about 10 to 20
mg/ft.sup.2. The luminescence data for these samples with low
(reduced) lubricant level are summarized in FIG. 2 and in TABLE 2
below. At these lubricant levels, no luminescence was detected from
the MP404 lubricant without tracer or doped with 500 ppm tracer
(note that in FIG. 2, the dots representing 500 ppm doping with
tracer and the dots representing "as-is" lubricant with no tracer
are indistinguishable from each other because they are superimposed
on the horizontal axis at zero detected luminescence). However, the
sample with 2,000 ppm tracer still emitted sufficient luminescence
to be detectable at a distance of 15 inches from the sample. This
indicates that to provide an optically detectable mark on the scrap
surface it is desirable to dope the lubricant with approximately
2,000 ppm of the fluorescent tracer used in this example. Clearly
the higher the tracer level, the lower the amount of lubricant that
can be detected. However, the cost of the tracer addition then
increases. A practical operating range can be worked out upon
determining what residual lubricant level is to be expected in
particular manufacturing operations.
2TABLE 2 Distance from Source (inches) MP404 as-is 500 ppm FY 1000
ppm FY 2000 ppm FY 5 0 0 7 15 10 0 0 3 9 15 0 0 0 4
EXAMPLE 3
[0066] The inherent fluorescence of the MP404 lubricant presents
some difficulty in that a sample with high lubricant level but no
tracer could emit the same luminescence as a sample with low
lubricant level containing the fluorescent tracer. Therefore a
method of eliminating background luminescence is desirable. To do
this, using the same scanner equipment, lubricant and fluorescent
tracer dopant as in the above Examples, luminescence was measured
with a set of filters placed in the luminescence scanner. In this
experiment, all samples were coated with the lubricant at a coating
weight of 125 mg/ft.sup.2, with and without the tracer, the latter
being designated "as-is." When the tracer was present, the doping
level was 2,000 ppm. The results (summarized in FIG. 3 and in TABLE
3 below) show that the luminescence is undetectable at a distance
of 15 inches from the samples with no tracer added or with tracer
added but using a red or dark red filter (note that in FIG. 3, the
dots representing "as-is" lubricant, i.e., with no tracer, for all
three filters are indistinguishable from each other because they
are superimposed on the horizontal axis representing zero detected
luminescence) With the orange filter, the luminescence from the
sample with no tracer was completely blocked, i.e., background
luminescence from the MP404 lubricant was eliminated. However, the
luminescence from the sample with tracer could readily be
detected.
3TABLE 3 Distance Dark Red Red Orange from Source (610-665 nm)
(610-665 nm) (570 nm) (inches) As-is 2000 ppm As-is 2000 ppm As-is
2000 ppm 5 0 4 0 6 0 22 10 0 2 0 3 0 16 15 0 0 0 0 0 8
[0067] It is to be understood that the invention is not limited to
the procedures and embodiments hereinabove specifically set forth,
but may be carried out in other ways without departure from its
spirit.
* * * * *