1、 WORLDWIDE ENGINEERING STANDARDS Material Specification GMW14671 Organic Coating Performance for Underhood and Underbody Components Copyright 2011 General Motors Company All Rights Reserved November 2011 Originating Department: North American Engineering Standards Page 1 of 5 1 Scope 1.1 Material De
2、scription. This standard gives performance requirements for organic-coat finishes on the surfaces of underhood and underbody components. It also gives opportunity to specify the type of coating material to be used. 1.2 Symbols. Not applicable. 1.3 Typical Applications. These coatings are typically u
3、sed on chassis components, as well as other underhood and underbody components. 1.4 Remarks. Eight types of paint are covered by this specification: Types A and B are both cathodic e-coats in two different thickness ranges. Type C is dip primer other than cathodic e-coat. Type D is powder coating. I
4、f Type E is specified, the applicator is free to choose Type A, B, C or D but must stay with this choice. Type F is to be further specified on the drawing using notes or a paint material specification. Type G is solvent- or water-based, spray-applied paint. Type H is a dip or dip spin high-performan
5、ce coating commonly specified for high-strength control arms, links and cradles/framing. Type H coatings are normally used on bare steel substrates. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ISO 2808 2.2 GM
6、 Standards/Specifications. 9984120 GMW14872 9984123 GMW15272 GMW3059 GMW15282 GMW3286 GMW15357 GMW14333 GMW15487 GMW14700 GMW15827 GMW14729 GMW15891 GMW14829 GMW16177 2.3 Additional References. TMC003 Material Safety Data Sheet guidance documents (available at ). 3 Requirements 3.1 Requirements on T
7、est Specimens. Not applicable. 3.2 General. 3.2.1 Coatings shall be free of Chrome VI. 3.2.2 Chrome VI used as an adhesion promoter is impermissible. 3.2.3 Post-treatment, if performed, shall be Chrome VI-free. 3.3 Coating Thickness. If parts have cavities that are prone to corrosion (e.g., cradle),
8、 a coating type must be selected which is able to protect the cavity areas with a minimum coating thickness of 10 m for Types A, B and C. Type H shall have interior cavity thickness defined in the MATSPC approval. Types A, B, C and H are usually chosen for this type of application. 3.3.1 Type A. Cat
9、hodic e-coat, coating thickness: 16 to 22 m. 3.3.2 Type B. Cathodic e-coat, coating thickness: 23 to 35 m. 3.3.3 Type C. Dip primer (except cathodic e-coat), coating thickness: 30 m. 3.3.4 Type D. Powder coating, coating thickness: 40 m. 3.3.5 Type E. Coating thickness to be as specified for Type A,
10、 B, C or D, whichever has been chosen for the application. 3.3.6 Type F. For this type, the thickness shall be defined on the drawing or in the specified paint material standard. 3.3.7 Type G. Spray paint (e.g., electrostatic application of solvent-based paints or water-based paints). Coating thickn
11、ess: 40 m. 3.3.8 Type H. Coatings for high-strength chassis underbody components. The high-strength components are fabricated from bare, non-zinc pre-coated steel substrates and normally welded. The parts must be descaled by sandblasting or Copyright General Motors Company Provided by IHS under lice
12、nse with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14671 Copyright 2011 General Motors Company All Rights Reserved November 2011 Page 2 of 5 acid cleaning to remove weld oxides. Treatment operations
13、must not have negative impact to the part performance. Residues (for example, of the blasting material or acid radicals) must be prevented. The parts shall be coated with approved materials after cleaning. Approved coatings and thickness are identified in the MATSPC database under this specification
14、 number. Coating systems typically consist of a corrosion-resistant primer and topcoat. Typical total coating thickness is 20 to 40 m. 3.3.9 Coating Thickness. Coating thicknesses (dry film builds) are to be measured per ISO 2808. Individual paint layers are to be measured and reported independently
15、. 3.4 Crosshatch Test. Paint adhesion shall be tested according to GMW14829, Rating 0 or 1 at delivery conditions and after high-humidity exposure (see 3.6). For Types C, F and G paints that are cured at 115 C or less on components exposed to service conditions in excess of 80 C: Parts shall be expo
16、sed for 120 5 h in a drying oven at +120 3 C before conducting the Crosshatch Test. 3.5 Corrosion Testing. 3.5.1 Cyclic Corrosion Test. See Table 1 for the testing criteria for parts by location on the vehicle. Perform this test on parts after exposure to cyclic corrosion testing per GMW14872. 3.5.1
17、.1 Types A through G. The parts shall meet the performance requirements of GMW15272. Part performance records shall be kept for reference and be available for review. Records shall indicate the part performance and the coupon mass loss at regular intervals (i.e., 5 cycles and 10 cycles). 3.5.1.2 Typ
18、e H. The parts shall have a corrosion rating of 9 or better at exposure 0 and A. The parts shall have a rating of 8 or better at exposure D. Corrosion rating per the GM Engineering Corrosion Standards Rating Scale in GMW15357. Part performance records shall be kept for reference and be available for
19、 review. Records shall indicate the part performance and the coupon mass loss at regular intervals (i.e., 5 cycles and 10 cycles). Note: Cyclic Corrosion Test must be done for Production Part Approval Process (PPAP). 3.5.2 Salt Spray Fog Test. The salt spray fog test may continue to be used as part
20、of a development program when directed by GM Materials Engineering. 3.5.2.1 Bare Substrates. 3.5.2.1.1 Parts shall be exposed to salt spray fog per GMW3286 for 336 h (Types A through G) and 1000 h for Type H. 3.5.2.1.2 There shall be no corrosion (except along scribe lines), blisters or any change o
21、f surface. Total corrosion creepback according to GMW15282 shall be 3 mm maximum for Types A through G and 1 mm for Type H. Slight rust is permitted but shall not exceed 20% of the length of exposed edges. 3.5.2.2 Zinc and Zinc Alloy-Coated Substrates. Salt spray fog test for 240 h (Types A through
22、G). 3.5.2.2.1 There shall be no corrosion or any change of surface allowed. Slight white corrosion is permitted at edges, but shall not exceed 20% of the length of edges. Red rust shall not exceed 5% of the length of edges. Creep corrosion within 8 mm from edges is permitted and shall be a maximum o
23、f one-third of the painted surface. 3.6 Resistance to High-Humidity Environment. Painted parts shall be exposed for 144 h to a high-humidity environment according to GMW14729, with no evidence of blistering or any other change of appearance. Copyright General Motors Company Provided by IHS under lic
24、ense with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14671 Copyright 2011 General Motors Company All Rights Reserved November 2011 Page 3 of 5 Table 1: Testing Criteria Note 1 Test Class Suffix Locati
25、on U/H Underhood U/B Underbody Gravelometer then Cyclic Corrosion (GMW14700, Method C and GMW14872) N/A Types A through G: Expose parts in Gravelometer per GMW14700, Method C, then expose the same parts in Cyclic Corrosion per GMW14872, (UB), All, 4 sp, Method 1/2, Exposure A. Type H: Expose parts i
26、n Gravelometer per GMW14700, Method C, then expose the same parts in Cyclic Corrosion per GMW14872, (UB), All, 4 sp, Method 1/2, Exposures 0, A and D. Cyclic Corrosion and Corrosion Creepback (GMW14872 and GMW15282) Scribe parts per GMW15282, then expose the same parts in Cyclic Corrosion per GMW148
27、72, (UH), All, 4 sp, Method 1/2, Exposure BEvaluate creepback per GMW15282 Note 2. N/A Note 1: The Testing Criteria will be indicated by the Test Class Suffix (for example, GMW14671 F-U/B). When the Test Class Suffix is not indicated (for example, GMW14671 F), the Testing Criteria will be based on t
28、he parts location on the vehicle per the following: Underhood Parts: Cyclic Corrosion and Corrosion Creepback per U/H Underhood column in Table 1. Underbody Parts: Gravelometer then Cyclic Corrosion per U/B Underbody column in Table 1. Note 2: Maximum allowable creepback per GMW15282 is 6 mm on bare
29、 steel and cast iron substrates, and 3 mm on all other substrates. 3.7 Stone Impact Resistance. 3.7.1 Types A through G. Test to GMW14700, Method C. Chip size rating shall be 7 minimum. Only chips to substrate will be rated. Chip frequency shall be a maximum of High. The test piece, wherever possibl
30、e, shall be the finished part. If this is impracticable, the test shall be conducted on samples cut from the finished part or, if necessary, specially prepared organic-coated test panels with equal substrate and painting material. 3.7.2 Type H. Type H coatings shall show a Stone Chip Rating of 9 min
31、imum, per GMW14700, Method C. The Gravelometer-tested parts are to be exposed to a salt spray environment per GMW3286 for 24 h in order to highlight the ratable chips. 3.8 Cure. There shall be a rating of 0 or 1 after the cure test per GMW15891. 3.9 Resistance of the Coating to Oil, Fuel, Battery Ac
32、id and Abrasion. If parts may be subject to abrasion or have contact with oil, fuel or battery acid, parts shall be tested according to 3.9.1, 3.9.2, 3.9.3, or 3.9.4. The necessity of one of these tests shall be defined on the drawing, using a suffix “Z” (see Example 2 in Section 8). 3.9.1 Oil Resis
33、tance. The test piece shall be immersed in engine oil (GMW15827 and GMW16177) and then exposed for 24 5 h in a drying oven at +100 3 C. After cooling to +23 5 C, the paint film shall show no separation or softening. 3.9.2 Fuel Resistance. Fuel resistance shall be determined according to GMW14333, Me
34、thod A, Rating 2. 3.9.3 Resistance to Battery Acid. Drops of a solution of sulfuric acid, 38% by mass (solution corresponds to battery acid) shall be placed on test parts. Then parts shall be stored in a vessel for 24 h at +23 5 C. After the test, the parts shall be cleaned by distilled water. There
35、 shall be no visible changes caused by the direct effect of battery acid. 3.9.4 Abrasion Resistance. Test abrasion resistance according to GMW15487, 0.7 L/m minimum. 4 Manufacturing Process Not applicable. 5 Rules and Regulations 5.1 Legal Regulations. All materials must satisfy applicable laws, rul
36、es, regulations and recommendations valid in the country of usage. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14671 Copyright 2011 G
37、eneral Motors Company All Rights Reserved November 2011 Page 4 of 5 5.2 Language. In the event of conflict between the English and domestic language, the English language shall take precedence. 5.3 Inspection and Rejection. Samples of components or materials released to a GM material specification s
38、hall be tested for conformity with the requirements of this material specification and approved by the responsible Engineering department prior to commencement of delivery of bulk supplies. A new approval must be received for any changes, e.g., properties, manufacturing process, location of manufact
39、ure, etc. If not otherwise agreed, all testing and documentation normally required for initial release must be completed. It is the responsibility of the supplier to inform the customer in a timely manner, without solicitation, and to include documentation of all modifications of materials and/or pr
40、ocesses and to apply for a new release. If not otherwise agreed, all release tests shall be repeated and documented by the supplier prior to commencement of delivery of non-conforming bulk supplies. In individual cases, a shorter test can be agreed to between the responsible Engineering department a
41、nd the supplier. 5.4 Initial Source Approval. No shipments shall be made by any supplier until representative initial production samples have been approved by the appropriate Materials Engineering department(s) as meeting the requirements of this specification. 5.5 Material Safety Data Sheets/Safety
42、 Data Sheets (MSDS/SDS). For new product submissions, or when a change in chemical composition of an existing product has occurred, a complete copy of the Material Safety Data Sheet/Safety Data Sheet must be submitted in compliance with the Globally Harmonized System of Classification and Labeling o
43、f Chemicals (GHS) requirements or other country-specific MSDS/SDS requirements. In addition, product MSDS/SDS submissions must be in compliance with specific country General Motors TMC003 Material Safety Data Sheet/Safety Data Sheet guidance documents where available. 5.6 All materials supplied to t
44、his 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 numb
45、er 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.
46、GHS Globally Harmonized System MATSPC Global repository of GM approved materials for corresponding GM Engineering Standards MSDS Material Safety Data Sheet PPAP Production Part Approval Process SDS Safety Data Sheet U/B Underbody U/H Underhood 8 Coding System This standard shall be referenced in oth
47、er documents, drawings, etc., as follows: Examples: 1. “PAINTED BLACK. PERFORMANCE TO GMW14671 B-U/B” is for cathodic e-coat 23 to 35 m thick, on an underbody component. 2. “PAINTED BLACK. PERFORMANCE TO GMW14671 D-U/H, Z. Z = RESISTANCE TO BATTERY ACID” is for a powder-coated component underhood th
48、at may come into contact with battery acid. 3. “PRETREAT PER 9984123, AND E-COAT PER 9984120. PERFORMANCE PER GMW14671 F-U/B” is for an underbody component that is pretreated using materials that have been approved to 9984123 and e-coated using materials that are approved to 9984120.Copyright Genera
49、l Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14671 Copyright 2011 General Motors Company All Rights Reserved November 2011 Page 5 of 5 9 Release and Revisions This standard was originated in October 2005. It was first approved by the Global Materials
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