GMNA 9984132 PDF

This specification covers the requirements for a black, waterborne autodeposition coating suitable for use on underhood, chassis and interior steel components. Application is by immersion of thoroughly cleaned steel. Maximum corrosion protection is afforded by the coating’s ability to form on any surface that can be wet.

Grade A is obsolete. Grade A currently contains hexavalent Chromium and is not to be specified for new applications.

Material Description. Five (5) grades of autodeposition coatings are available and are defined herein as Grades A, B, C, D and E.

Grade A is a low VOC (Volatile Organic Compounds) waterborne material with a cure temperature of 180 to 200C.

Grade B and C are zero VOC, waterborne materials that oven cure in the range of 100 to 115C.

Grade D is a very low VOC, waterborne material with a cure temperature of 130 to 190C.

Grade E is a low VOC, 2 coat, waterborne material with a cure temperature of 150 to 170C.

All grades are generally used without topcoating. However, compatible topcoats may be used if acceptable performance is verified prior to production usage. Autodeposition should not be specified for aluminum substrates or aluminized steel. Coating of galvanized steel should be verified and tested on a case-by-case basis prior to approval.

• Grades B and C should not be used when components are exposed to service conditions in excess of 120ºC. Components should be evaluated under operating conditions when the service temperature is between 95 and 120ºC.

Grade C is intended for use at low film build in interior or similar applications that require only moderate corrosion resistance.

Grade D has improved resistance to fastener chatter. Grade E has reduced gloss, is highly flexible, heat resistant, and rubber bondable.

Grade E is also moderately UV resistant.

On engineering drawings, this standard requires the grade to be designated which defines the performance level for the coating.

Remarks. VOC Grade

A must not exceed 240g/l.

• Grade B is VOC free.

Grade C is VOC free.

Grade D must not exceed 25 g/l.

Grade E has two coats; the first is VOC free, and the second coat must not exceed 110 g/l.