Description / Abstract: Material Description.

This coating system must be free of hexavalent chromium, per GMW3059 requirements. The plating shall be shown on the part drawing. Table 1 lists the common plating thickness codes covered by this specification.

It is recommended to use these common codes to avoid product complexity.

This plating is at present approved in clear (bright) color only. Black color (passivation product) as shown in Table 1 is not approved yet. Any other colors (where color is developed by adding pigment), if required, do not need a specially approved source for the color. Establish availability at one of the sources approved to the required post-supplementary code (suffix) before putting any color other than clear (Bright) on the drawing.

Symbols. Not applicable.

Applicability.

Zinc plating is typically applied on small-sized to medium-sized ferrous parts such as castings, fasteners, stampings, and clips.

Zinc-plated parts or their corrosion products must not come in contact with stressed polyamides 6 or 66.

Zinc-plating types without supplementary treatment are also used as a basecoat for an additional paint. This coating must be so applied that no negative influence in appearance and adhesion appears (e.g., blistering by effusion of hydrogen).

Remarks.

This specification covers the basic requirements for electroplated zinc applied to fasteners, clips, and small and medium-sized ferrous parts, such as castings and stampings. This specification also provides for plating thickness, use or non-use of supplementary treatments and corrosion and for mechanical plating. GM Materials Engineering approvals for this finish are specific to the post-supplementary treatment (suffix) evaluated for initial chemical/applicator approval (reference Section 6).

The use of this specification to plate other parts, including, but not limited to, stampings or roll-formed parts for body or chassis applications must be reviewed and approved by the responsible materials engineering organization.