WORLDWIDE Material Specification

ENGINEERING GMW15645
Paint
STANDARDS

Non-Decorative Plastic Powder Coatings

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Note that epoxies should not be used in
1 Scope applications where they are exposed to sunlight.
This specification covers plastic powder coatings 1.4 Remarks. The Remarks column in the
that are fused on application to properly prepared Approved Source List will indicate for which type
metal substrates to form a continuous, durable and suffix code each product is approved.
coating for purposes such as wear resistance or
squeak prevention. The powders may be applied 2 References
by electrostatic spray, fluidized bed, or a variation Note: Only the latest approved standards are
thereof. applicable unless otherwise specified.
1.1 Material Description. Five types are covered 2.1 External Standards/Specifications.
by this specification, as follows:
ASTM D870 ISO 4892-1
• Type I: a thick epoxy coating for usages such
ASTM D6677 ISO 4892-2
as seat belt anchor plates, to provide
corrosion resistance and prevent metal edges ISO 105-A03 SAE J2527
from cutting the webbing. 2.2 GM Standards/Specifications.
• Type II: a thinner epoxy coating used on 9984303 GMW3286
various seat parts and other parts where B 040 0900 GMW3402
prevention of metal-to-metal contact is EMS 9309574 GMW14162
required and where some degree of wear
GM4383M GMW14333
resistance is necessary.
GM6094M GMW14700
• Type III: a thick nylon 11 or nylon 12 coating
GMW3001 GMW14701
used on parts which are susceptible to high
wear, to prevent squeaks, or to provide a GMW3059 GMW14729
thermal barrier. GMW3208
• Type IV: a thinner nylon 11 or nylon 12
coating. 3 Requirements
• Type V: a polyester coating for usages such Unless otherwise indicated, the requirements shall
as seat tracks, where some degree of wear pertain to all types and suffix codes.
resistance is necessary. 3.1 Chemical Requirements. Any phosphated
Note: Some nylons must use a primer to meet the components must use a phosphate sealer
performance requirements of this specification. approved to 9984303.
1.2 Symbols. Suffix codes are to be added to the 3.2 Physical Requirements.
drawing notes to indicate location on the vehicle 3.2.1 Resin. Types I and II shall be epoxy. Types
and if the coating is exposed to sunlight: III and IV shall be nylon 11 or nylon 12. Type V
• Interior (IN) = Interior applications. shall be polyester.
• Exterior (EX) = Exterior applications (includes 3.2.2 Appearance. The coating must be smooth,
underhood and underbody). uniform and continuous with no evidence of voids,
craters, sags, blisters, or other surface defects in
• Ultraviolet (UV) = Applications exposed to the area specified to be coated.
sunlight whether interior or exterior.
3.2.3 Thickness.
1.3 Typical Applications. These coatings are
typically used for corrosion resistance, seat belt 3.2.3.1 Unless otherwise specified on the part
anchor plates, prevention of metal-to-metal contact drawing:
such as on seat parts, protection from wear, etc. • Type I shall be 0.25 mm thick minimum.
• Type II shall be 0.025 mm thick minimum.
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 GMW15645 GM WORLDWIDE ENGINEERING STANDARDS

• Type III shall be 0.38 ± 0.12 mm thick. 3.4 Additional Requirements. The following tests
• Type IV shall be 0.15 ± 0.08 mm thick. are for new material approvals only. They shall be
conducted on coated panels.
• Type V shall be 0.127 ± 0.025 mm thick.
3.4.1 Compatibility (Type I only). The coating
3.2.3.2 Due to the thickness of these coatings, they material must not stain, degrade or have any other
should not be used in fastened joints. detrimental effect on polyester seat belt webbing
3.3 Performance Requirements. The following when tested per the following procedure:
tests are to be performed at 22 ± 2°C and 50 ± 5% 3.4.1.1 A light colored sample of seat belt webbing
Relative Humidity (RH) unless otherwise specified. shall be placed in contact with the coating and
Testing shall be performed on parts or placed in a closed container for two weeks at
representative coated panels. Coated test panels 93 ± 2°C in an air circulating oven. A control
shall be used for material qualification only. sample of webbing not in contact with the coating
3.3.1 Cure (Types I, II and V only). There shall be shall be placed in a similar container and exposed
no softening of the coating or evidence of at the same time and temperature. After exposure,
tackiness when a rag saturated with a solvent comparison and evaluation of detrimental effects
recommended by the powder supplier is placed on shall be made versus the control.
the coating for approximately 30 s. 3.4.2 Environmental Resistance. After exposure
3.3.2 Adhesion and Humidity. and impact per the procedure in Appendix A, the
3.3.2.1 Suffix Codes EX and EX/UV. Parts or coating must show no chipping, cracking,
panels shall be exposed for 96 h to water fog blistering, softening, effect on adjacent materials
humidity per GMW14729. After exposure, there (effect on corrosion resistance of the metal,
shall be no blistering or appearance change. Parts staining, etc.), objectionable change in color or
shall rate 6 or better when tested per the other detrimental effects (mushrooming without
procedure in Appendix B. cracking when impacted is acceptable).
3.3.2.2 Suffix Codes IN and IN/UV. Parts or 3.4.3 Resistance to Wear. Coated panels shall be
panels shall be exposed for 24 h to water fog subjected to 1000 cycles with CS17 wheels and a
humidity per GMW14729. After exposure, there 1000 g load on the Taber Abraser, per GMW3208.
shall be no blistering or appearance change. Parts Weight loss of Types I and II shall be 0.06 g,

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shall rate 6 or better when tested per the maximum. Weight loss of Types III, IV and V shall
procedure in Appendix B. be 0.025 g, maximum.
3.3.3 Neutral Salt Spray. 3.4.4 Interior Finish Durability (Suffix Code
IN/UV only).
3.3.3.1 Suffix Code EX. There shall be no more
than 10% blistering or peeling of the powder 3.4.4.1 Test for Colorfastness to light per
coating after 168 h neutral salt spray exposure per GMW14162/D/601.1 Kilojoules per square meter
GMW3286. (kj/m2). After exposure, coated panels shall show
no objectionable gloss or color change, chalking,
3.3.3.2 Suffix Code EX/UV. There shall be no
or other visible surface deterioration.
more than 10% blistering or peeling of the powder
coating after 336 h neutral salt spray exposure per 3.4.4.2 Effect of Cleaners. Coated panels shall be
GMW3286. tested per GMW3402 Procedure B Codes 1, 2, 3,
4, and 5. There shall be no discoloration of the
3.3.3.3 Suffix Codes IN and IN/UV. After 96 h
surface or transfer of color to the cloth. The white
exposure in neutral salt spray per GMW3286, there
cheesecloth shall have a rating better than Grade 4
shall be no red rust or white corrosion on coated
on the chromatic transference scale per ISO 105-
panels or parts.
A03.
3.3.4 Water Soak. Parts or panels shall be soaked
3.4.5 Exterior Finish Durability (Suffix Code
for 127.5 ± 7.5 minutes in Deionized Water at
EX/UV only). Coated panels shall be exposed in
38 ± 1°C per ASTM D870. After exposure, there
xenon arc weatherometer per ISO 4892-1 and
shall be no defects or metal corrosion. Samples
ISO 4892-2 as specified in 3.4.5.1 or
shall rate 6 or better when tested per the
per SAE J2527 Extended UV Filters as specified
procedure in Appendix B.
in 3.4.5.2. Evaluate per 3.4.5.3.
3.3.5 Resistance to Stone Impact (Suffix Code
3.4.5.1 ISO Procedure. Test as per the conditions
EX). Samples shall rate 7 or higher after testing
of ISO 4892-1 and ISO 4892-2, as shown here in
per GMW14700, Method C.
Table 1. Panels shall be exposed for >3000 kJ/m2.

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 GM WORLDWIDE ENGINEERING STANDARDS GMW15645

Table 1: ISO Procedure Conditions 5.2 All materials supplied to this standard must
comply with the requirements of GMW3059,
Parameter Requirement
Restricted and Reportable Substances for
Inner- and Outerfilter Borosilicate Parts.
Radiant exposure 0.50 W/m2 at 340 nm
6 Approved Sources
Test program Cam Number 102 ± 0.5 minutes light
Engineering qualifications of an approved source
7 only. 18 ± 0.5 minutes
light and spray are required for this standard. Only sources listed
in the GM Materials File (i.e., GM Supply Power)
Black-standard temperature +80 ± 3°C under this standard number have been qualified by
engineering as meeting the requirements of this
standard.
3.4.5.2 SAE Procedure. Test as per the conditions
of SAE J2527 Extended UV Filters. For other GM locations, the responsible
engineering group should be contacted to obtain
3.4.5.3 Evaluation. After exposure, there shall be the approved source in that individual country.
no indications of surface tackiness or
embrittlement, blooming, blistering, change in
hardness, color or gloss, or other factors which
7 Notes
might affect the function or appearance of the part. 7.1 Glossary. Not applicable.
3.4.6 Resistance to Various Environmental 7.2 Acronyms, Abbreviations, and Symbols.
Inputs (Suffix Code EX). EX Exterior
3.4.6.1 Temperature Resistance. After test IN Interior
panels are baked at 100 ± 2°C for 24 ± 1 h, there 2
kJ/m Kilojoules per square meter
shall be no evidence of coating breakdown.
RH Relative Humidity
3.4.6.2 Fuel Resistance. Coated panels shall
meet requirements of GMW14333, A, Rating 2. UV Ultraviolet
Adhesion shall be tested using the method in
Appendix B. Panels shall rate 8 or better. 8 Coding System
3.4.6.3 Oil Resistance. Test panels shall be This standard shall be referenced in other
immersed in engine oil per B 040 0900, EMS documents, drawings, etc., as follows:
9309574 and GM6094M and then exposed for Material per GMW15645 Type W-YY/ZZ
24 ± 1 h in a drying oven at +100 ± 3°C. Evaluate Where:
after cooling to +23 ± 5°C. There shall be no
W is one of five types described in paragraph 1.1,
discoloration, change in gloss, shrinkage, swelling,
YY is either IN for interior applications or EX for
dissolution, wrinkling or creasing, blistering,
exterior applications, and ZZ is UV, which is only
distortion, or cracking.
used if the coated component will be exposed to
3.4.6.4 Chemical Spot Test. Panels shall be sunlight.
tested per GMW14701, Methods 1 and 2, using 10,
Examples:
1.0 and 0.1% solutions by weight of Analytical
Reagents of the following: GMW15645 Type IV-IN/UV is a nylon coating that
is used on a component that is located inside the
• Acetic Acid vehicle where it may be exposed to through glass
• Hydrochloric Acid sunlight.
• Sulfuric Acid
GMW15645 Type II-EX is an epoxy coating that is
• Sodium Hydroxide
used on a component that is located underhood or
After exposure, panels shall rate 8 minimum. underbody.

4 Manufacturing Process 9 Release and Revisions

Not applicable. 9.1 Release. This standard originated in July 2007,
replacing GM4383M. It was first approved by the
5 Rules and Regulations Global Finish Team in June 2008. It was first
5.1 All materials supplied to this standard must published in June 2008.
comply with the requirements of GMW3001, Rules
and Regulations for Material Specifications.

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 GMW15645 GM WORLDWIDE ENGINEERING STANDARDS

Appendix A - Environmental Resistance Test

-30 ± 2°C. The impact shall be done with an impact

A1 Procedure head 25 mm long with a 3.2 mm radius on the
The coated metal panel shall be subjected two impacting edge. Samples shall be impacted across
cycles of the environmental cycle shown in Table the edge of the panel (almost point contact) with
A1 and described in the paragraph below. The 0.5 kg dropped 50 mm. See Figure A1.
panel may be left at -30°C over the weekend.

Table A1: Environmental Cycle

24 h at 90 ± 2°C
24 h per GMW14729
8 h at -30 ± 2°C
16 h at 70 ± 2°C
24 h per GMW14729
8 h at -30 ± 2°C

In the last cycle the 70°C exposure shall be for Figure A1: Impact Head and Test Panel
23 h, and the second humidity exposure shall be
replaced with 17 h neutral salt spray per
GMW3286. After exposure to the last 8 h at -30°C,
the sample shall be subjected to an impact at
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 GM WORLDWIDE ENGINEERING STANDARDS GMW15645

Appendix B - Adhesion Test

coating. Be sure to fully cut through to the metal
B1 Test Equipment surface. Make a perpendicular incision across the
B1.1 Cutting Tool - Razor knife ends of the parallel lines such that each parallel
line is bisected. Be sure to fully cut through the
B1.2 Cutting Guide - Steel or other hard metal
coating to the metal. Use sharp blades, as dull
straight edge to ensure straight cuts
blades tend to cause more peeling. When cutting,
B1.3 Lifting Tool - Needle nose pliers hold the knife perpendicular to the surface and
avoid any side motion.
B2 Test Material B3.3 After making the required cuts, brush the
B2.1 After removing the samples from the humidity coating lightly with a soft brush or tissue to remove
chamber, dry them by blotting with absorbent any detached flakes or ribbons of coating.
paper or cloth. B3.4 Carefully undercut the bisected lines with a
B2.2 The recovery time after exposure and before razor knife to lift up a flap of coating. The flap
tape adhesion testing shall be 10 to 15 minutes. should be 2 to 3 mm in length.
B3.5 Grasp the flap of coating with needle nose
B3 Test Method pliers, and with an even motion, pull back on the
B3.1 Select a representative area or an area flap of coating along the parallel cut lines. Samples
suspected of having poor coating adhesion on the shall be rated according to Table B1.
coated surface to be tested. Do not select sagged,
solvent popped or other obviously defective areas, B4 Report
as these defects should be rated separately. B4.1 Record the rating.
B3.2 With a sharp pointed razor knife cut parallel B4.2 Submit the tested part or panel for review.
lines (6 to 12 mm apart, about 25 mm long) into the

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Table B1: Rating System per ASTM D6677
Rating Description
10 Coating is extremely difficult to remove; fragments no larger than approximately 0.8 by 0.8 mm
removed with great difficulty.
8 Coating is difficult to remove; chips ranging from approximately 1.6 by 1.6 mm to 3.2 by 3.2 mm can
be removed with difficulty.
6 Coating is somewhat difficult to remove; chips ranging from approximately 3.2 by 3.2 mm to 6.3 by
6.3 mm can be removed with slight difficulty.
4 Coating is somewhat difficult to remove; chips in excess of 6.3 by 6.3 mm can be removed by
exerting light pressure with the knife blade.
2 Coating is easily removed; once started with the knife blade, the coating can be grasped with one’s
fingers and easily peeled to a length of at least 6.3 mm.
0 Coating can be easily peeled from the substrate to a length greater than 6.3 mm.

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