GMW GMW14664 PDF

Material Description. Powder coatings for the purpose of this specification shall be defined as organic resin material in a finely powdered state, for application to suitably prepared ferrous or nonferrous metallic surfaces, followed by heat cure (to develop the desired characteristics in the finished film). Generally, a specific material requirement and color will be shown on the engineering drawing, otherwise any powder coating may be used, provided that the test requirements of the specifications are met.

These coatings are intended to ensure adequate protection against corrosion on surfaces of both external and internal parts of passenger and commercial vehicles.

In order to meet the requirements of this specification, it is necessary for components to undergo a suitable cleaning process/removal operation (including scale or other oxide layers). Cleaning is to be followed by an appropriate pretreatment before powder coat application.

The pretreatment (e.g., low zinc, 3-cations-phosphating) shall ensure good adhesion. Iron phosphate is prohibited by GM Europe (GME) for Type A and Type C. It is not preferred, but is permitted by GM North America (GMNA). Primer may be used if specified on the engineering drawing.

These coatings may be applied by electrostatic spray or fluidized bed techniques.

Symbols. Not applicable.

Applicability. Parts with a coating according to this specification can be classified into one (1) of the following Type A, Type B, or Type C categories. Type A: Body outer decorative parts such as roof rails, guide rails, and decorative moldings. Requirements for these components are specified in GMW3005. Type A parts must also meet the requirements for corrosion resistance as specified in GMW14669. See Appendix A, Table A3 for testing requirements for new exterior topcoats. Appendix C, Table C1 is for Exterior Quality Control Testing. Type A is divided into two (2) Classes:

• Class 1: Smooth.

• Class 2: Textured.

Each of these Classes could be subdivided into two (2) Grades if specific performance is required (optional).

• Grade I: Anti-slip.

• Grade II: Wear resistant.

Type B: Body inner only for passenger compartments such as partition grille, and brackets.

• Area I: Direct sunlight, all specific colors.

• Area II: Indirect sunlight, non-color-matched.

Type C: Engine compartment and underbody components.

• All locations.

• Part type and location must be specified on the engineering drawing.

• This specification is not applicable for the body itself and body elements (such as doors, hood, and tailgate).

• Certain types of powder coatings e.g., Epoxy, when exposed to Ultraviolet (UV) radiation, show a tendency to "chalk". This feature does not affect the service performance of the material. These powder coat finishes are unsuitable for Type B in direct sunlight exposure areas.