|Publication Date:||1 October 2004|
This specification covers the basic requirements for electroplated zinc applied to iron and steel substrates with provision for plating thickness, use or non-use of supplementary treatments and corrosion resistance. Provision is also made to specify mechanical plating.
Material Description. This coating system must be free of hexavalent chromium, per GMW3059 requirements. The plating shall be shown on the part drawing as per the example shown in Section 7. Table 1 lists the common types of finishes covered by this specification. However, it may be necessary to devise additional combinations of finishes as follows: (1) the first one or two digits depict the minimum plated metal thickness in micrometers; (2) the character that follows indicates the use or non-use of supplementary (e.g. chromate) treatment; (3) the Neutral Salt Spray (NSS) hours to base metal/white corrosion are shown next; (4) the next character, when shown, indicates the use of a post-supplementary treatment (e.g. wax); (5) the final character, when shown, indicates the need to heat treat the finish prior to NSS testing; (6) the color may be indicated, if desired, in parentheses at the end of the suffix.
Cross-Reference of Replaced Specifications.
Typical Application. Zinc plating is typically applied on small 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).