Non-Decorative Plastic Powder Coatings
© Copyright 2008 General Motors Corporation All Rights Rerved
June 2008 Originating Department: North American Engineering Standards
Page 1 of 5
1 Scope
This specification covers plastic powder coatings that are fud on application to properly prepared metal substrates to form a continuous, durable coating for purpos such as wear resistance or squeak prevention. The powders may be applied by electrostatic spray, fluidized bed, or a variation thereof.
priceless1.1 Material Description. Five types are covered by this specification, as follows: •
Type I: a thick epoxy coating for usages such as at belt anchor plates, to provide corrosion resistance and prevent metal edges from cutting the webbing.
•
Type II: a thinner epoxy coating ud on various at parts and other parts where prevention of metal-to-metal contact is required and where some degree of wear resistance is necessary.
•
Type III : a thick nylon 11 or nylon 12 coating ud on parts which are susceptible to high wear, to prevent squeaks, or to provide a thermal barrier.
• Type IV: a thinner nylon 11 or nylon 12 coating.
•
Type V: a polyester coating for usages such as at tracks, where some degree of wear resistance is necessary.
Note: Some nylons must u a primer to meet the performance requirements of this specification.
1.2 Symbols. Suffix codes are to be added to the drawing notes to indicate location on the vehicle and if the coating is expod to sunlight: • Interior (IN) = Interior applications.
• Exterior (EX) = Exterior applications (includes underhood and underbody).
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Ultraviolet (UV) = Applications expod to sunlight whether interior or exterior.
1.3 Typical Applications. The coatings are typically ud for corrosion resistance, at belt anchor plates, prevention of metal-to-metal contact such as on at parts, protection from wear, etc.
Note that epoxies should not be ud in applications where they are expod to sunlight.
1.4 Remarks. The Remarks column in the Approved Source List will indicate for which type and suffix code each product is approved.
2 References
Note: Only the latest approved standards are applicable unless otherwi specified. 2.1 External Standards/Specifications. ASTM D870 ISO 4892-1 ASTM D6677 ISO 4892-2 ISO 105-A03
SAE J2527
2.2 GM Standards/Specifications.
9984303 GMW3286 B 040 0900 GMW3402 EMS 9309574 GMW14162
GM4383M GMW14333 GM6094M GMW14700 GMW3001 GMW14701 GMW3059 GMW14729 GMW3208
3 Requirements
little black dressUnless otherwi indicated, the requirements shall pertain to all types and suffix codes.
3.1 Chemical Requirements. Any phosphated components must u a phosphate aler approved to 9984303.
3.2 Physical Requirements.
3.2.1 Resin. Types I and II shall be epoxy. Types III and IV shall be nylon 11 or nylon 12. Type V shall be polyester.
3.2.2 Appearance. The coating must be smooth, uniform and continuous with no evidence of voids, craters, sags, blisters, or other surface defects in the area specified to be coated. 3.2.3 Thickness.
3.2.3.1 Unless otherwi specified on the part drawing: • Type I shall be 0.25 mm thick minimum. •
Type II shall be 0.025 mm thick minimum.
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• Type III shall be 0.38 ± 0.12 mm thick. •
Type IV shall be 0.15 ± 0.08 mm thick.
• Type V shall be 0.127 ± 0.025 mm thick.
3.2.3.2 Due to the thickness of the coatings, they should not be ud in fastened joints.
3.3 Performance Requirements. The following tests are to be performed at 22 ± 2°C and 50 ± 5% Relative Humidity (RH) unless otherwi specified. Testing shall be performed on parts or reprentative coated panels. Coated test panels shall be ud for material qualification only.
3.3.1 Cure (Types I, II and V only). There shall be no softening of the coating or evidence of tackiness when a rag saturated with a solvent recommended by the powder supplier is placed on the coating for approximately 30 s. 3.3.2 Adhesion and Humidity.
3.3.2.1 Suffix Codes EX and EX/UV. Parts or panels shall be expod for 96 h to water fog humidity per GMW14729. After exposure, there shall be no blistering or appearance change. Parts shall rate 6 or better when tested per the procedure in Appendix B.
3.3.2.2 Suffix Codes IN and IN/UV. Parts or panels shall be expod for 24 h to water fog humidity per GMW14729. After exposure, there shall be no blistering or appearance change. Parts shall rate 6 or better when tested per the procedure in Appendix B. 3.3.3 Neutral Salt Spray.
3.3.3.1 Suffix Code EX. There shall be no more than 10% blistering or peeling of the powder coating after 168 h neutral salt spray exposure per GMW3286.
3.3.3.2 Suffix Code EX/UV. There shall be no more than 10% blistering or peeling of the powder coating after 336 h neutral salt spray exposure per GMW3286.
3.3.3.3 Suffix Codes IN and IN/UV. After 96 h exposure in neutral salt spray per GMW3286, there shall be no red rust or white corrosion on coated panels or parts.
3.3.4 Water Soak. Parts or panels shall be soaked for 127.5 ± 7.5 minutes in Deionized Water at 38 ± 1°C per ASTM D870. After exposure, there shall be no defects or metal corrosion. Samples shall rate 6 or better when tested per the procedure in Appendix B.
3.3.5 Resistance to Stone Impact (Suffix Code EX). Samples shall rate 7 or higher after testing per GMW14700, Method C.
3.4 Additional Requirements. The following tests
are for new material approvals only. They shall be conducted on coated panels.
3.4.1 Compatibility (Type I only). The coating material must not stain, degrade or have any other detrimental effect on polyester at belt webbing when tested per the following procedure:
catchy3.4.1.1 A light colored sample of at belt webbing shall be placed in contact with the coating and placed in a clod container for two weeks at 93 ± 2°C in an air circulating oven. A control sample of webbing not in contact with the coating shall be placed in a similar container and expod at the same time and temperature. After exposure, comparison and evaluation of detrimental effects shall be made versus the control.
3.4.2 Environmental Resistance. After exposure and impact per the procedure in Appendix A, the coating must show no chipping, cracking, blistering, softening, effect on adjacent materials (effect on corrosion resistance of the metal, staining, etc.), objectionable change in color or other detrimental effects (mushrooming without cracking when impacted is acceptable).
3.4.3 Resistance to Wear. Coated panels shall be subjected to 1000 cycles with CS17 wheels and a 1000 g load on the Taber Abrar, per GMW3208. Weight loss of Types I and II shall be 0.06 g, maximum. Weight loss of Types III, IV and V shall be 0.025 g, maximum.
3.4.4 Interior Finish Durability (Suffix Code IN/UV only).
3.4.4.1 Test for Colorfastness to light per GMW14162/D/601.1 Kilojoules per square meter (kj/m 2). After exposure, coated panels shall show no objectionable gloss or color change, chalking, or other
visible surface deterioration.
3.4.4.2 Effect of Cleaners. Coated panels shall be tested per GMW3402 Procedure B Codes 1, 2, 3, 4, and 5. There shall be no discoloration of the surface or transfer of color to the cloth. The white cheecloth shall have a rating better than Grade 4 on the chromatic transference scale per ISO 105-A03.
3.4.5 Exterior Finish Durability (Suffix Code EX/UV only). Coated panels shall be expod in xenon arc weatherometer per ISO 4892-1 and ISO 4892-2 as specified in 3.4.5.1 or per SAE J2527 Extended UV Filters as specified in 3.4.5.2. Evaluate per 3.4.5.3.
3.4.5.1 ISO Procedure. Test as per the conditions of ISO 4892-1 and ISO 4892-2, as shown here in Table 1. Panels shall be expod for >3000 kJ/m 2.
GM WORLDWIDE ENGINEERING STANDARDS GMW15645
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June 2008 Page 3 of 5
Table 1: ISO Procedure Conditions
Parameter Requirement
Inner- and Outerfilter Borosilicate Radiant exposure
0.50 W/m 2 at 340 nm Test program Cam Number 7
102 ± 0.5 minutes light only. 18 ± 0.5 minutes light and spray Black-standard temperature
+80 ± 3°C
3.4.5.2 SAE Procedure. Test as per the conditions of SAE J2527 Extended UV Filters.
3.4.5.3 Evaluation. After exposure, there shall be no indications of surface tackiness or embrittlement, blooming, blistering, change in hardness, color or gloss, or other factors which might affect the function or appearance of the part. 3.4.6 Resistance to Various Environmental Inputs (Suffix Code EX).
3.4.6.1 Temperature Resistance. After test panels are baked at 100 ± 2°C for 24 ± 1 h, there shall be no evidence of coating breakdown.
3.4.6.2 Fuel Resistance. Coated panels shall meet requirements of GMW14333, A, Rating 2. Adhesion shall be tested using the method in Appendix B. Panels shall rate 8 or better.
3.4.6.3 Oil Resistance. Test panels shall be immerd in engine oil per B 040 0900, EMS 9309574 and GM6094M and then expod for 24 ± 1 h in a drying oven at +100 ± 3°C. Evaluate after cooling to +23 ± 5°C. There shall be no discoloration, change in gloss, shrinkage, swelling, dissolution, wrinkling or creasing, blistering, distortion, or cracking.
3.4.6.4 Chemical Spot Test. Panels shall be tested per GMW14701, Methods 1 and 2, using 10, 1.0 and 0.1% solutions by weight of Analytical Reagents of the following:
• Acetic Acid • Hydrochloric Acid • Sulfuric Acid • Sodium Hydroxide
After exposure, panels shall rate 8 minimum.
4 Manufacturing Process
Not applicable.
5 Rules and Regulations
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5.1 All materials supplied to this standard must comply with the requirements of GMW3001, Rules and Regulations for Material Specifications.
5.2 All materials supplied to this standard must comply with the requirements of GMW3059,
Restricted and Reportable Substances for
Parts.
6 Approved Sources
Engineering qualifications of an approved source are required for this standard. Only sources listed in the GM Materials File (i.e., GM Supply Power) under this standard number have been qualified by engineering as meeting the requirements of this standard.
For other GM locations, the responsible engineering group should be contacted to obtain the approved source in that individual country.
7 Notes
7.1 Glossary. Not applicable.
7.2 Acronyms, Abbreviations, and Symbols. EX Exterior IN Interior乐知英语培训
kJ/m 2 Kilojoules per square meter RH Relative Humidity UV Ultraviolet
8 Coding System
This standard shall be referenced in other documents, drawings, etc., as follows: Material per GMW15645 Type W-YY/ZZ Where:
W is one of five types described in paragraph 1.1, YY is either IN for interior applications or EX for exterior applications, and ZZ is UV, which is only ud if the coated component will be expod to sunlight. Examples:2013江苏高考英语答案
GMW15645 Type IV-IN/UV is a nylon coating that is ud on a component that is located inside the vehicle where it may be expod to through glass sunlight.
GMW15645 Type II-EX is an epoxy coating that is ud on a component that is located underhood or underbody.
9 Relea and Revisions
9.1 Relea. This standard originated in July 2007, replacing GM4383M. It was first approved by the Global Finish Team in June 2008. It was first published in June 2008.
GMW15645 GM WORLDWIDE ENGINEERING STANDARDS
© Copyright 2008 General Motors Corporation All Rights Rerved
Page 4 of 5 June 2008
Appendix A - Environmental Resistance Test
A1 Procedure
The coated metal panel shall be subjected two cycles of the environmental cycle shown in Table A1 and described in the paragraph below. The 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 23 h, and the cond 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
-30 ± 2°C. The impact shall be done with an impact head 25 mm long with a 3.2 mm radius on the impacting edge. Samples shall be impacted across the edge of the panel (almost point contact) with 0.5 kg dropped 50 mm. See Figure A1.
Figure A1: Impact Head and Test Panel
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Appendix B - Adhesion Test B1 Test Equipment
B1.1 Cutting Tool - Razor knife
B1.2 Cutting Guide - Steel or other hard metal straight edge to ensure straight cuts B1.3 Lifting Tool - Needle no pliers
B2 Test Material
B2.1 After removing the samples from the humidity chamber, dry them by blotting with absorbent paper or cloth.
B2.2 The recovery time after exposure and before tape adhesion testing shall be 10 to 15 minutes.
B3 Test Method
B3.1 Select a reprentative area or an area suspected of having poor coating adhesion on the coated surface to be tested. Do not lect sagged,应用题教学
solvent popped or other obviously defective areas,
as the defects should be rated parately. B3.2 With a sharp pointed razor knife cut parallel lines (6 to 12 mm apart, about 25 mm long) into the coating. Be sure to fully cut through to the metal surface. Make a perpendicular incision across the ends of the parallel lines such that each parallel li
ne is bicted. Be sure to fully cut through the coating to the metal. U sharp blades, as dull blades tend to cau more peeling. When cutting, hold the knife perpendicular to the surface and avoid any side motion.
B3.3 After making the required cuts, brush the coating lightly with a soft brush or tissue to remove any detached flakes or ribbons of coating.
B3.4 Carefully undercut the bicted lines with a razor knife to lift up a flap of coating. The flap should be 2 to 3 mm in length.
B3.5 Grasp the flap of coating with needle no pliers, and with an even motion, pull back on the flap of coating along the parallel cut lines. Samples shall be rated according to Table B1.
B4 Report B4.1 Record the rating. B4.2 Submit the tested part or panel for review.
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.
