Machinery's Handbook, 31st Edition
Plating Standards 1643 Coatings range from thin clear to light gray-green, to thick dark-green coatings. The clear coatings are used as a base for subsequent clear lacquers or paints to produce a final appearance similar to clear anodizing on aluminum. The light gray-green coatings are used in most applications which are to be painted. The thick, dark-green coating offers the best combination of abrasion resistance, protective value and paint base characteristics. Type/Class Typical Thickness Comments Type I, Light coating. Class A 0.2 mil Tan coating (HAE) Grade 1 … Without post treatment (dyed) Grade 2 … With biflouride-dichromate post treatment Class C 0.3 mil Light green coating (Dow #17) Type II, Heavy coating Class A 1.5 mil Hard brown coating (HAE) Grade 1 … Without post treatment Grade 3 … With biflouride-dichromate post treatment Grade 4 … With biflouride-dichromate post treatment including moist heat aging Grade 5 With double application of biflouride-dichromate post treatment including moist heat aging. Class D 1.2 mil Dark green coating (Dow #17) Electroless Nickel, AMS 2404C, AMS 2405B, AMS 2433B: Is typically used as a coating to provide a hard-ductile, wear-resistant, and corrosion-resistant surface for operation in service up to 1000F, to provide uniform build-up on complex shapes. AMS 2404C, is deposited directly on the basis metal without a flash coating of other metal, unless otherwise specified. AMS 2405B, is deposited directly on the basis metal except where parts fabricated from corrosion resistant steels or alloys where a “strike” coating of nickel or other suitable metal is required, unless otherwise specified. AMS 2433B, is a type of electroless nickel typically used to enhance the solderability of surfaces, but usage is not limited to such applications. Generally, the plate shall be placed directly on the basis metal. However, aluminum alloys shall be zinc immersion coated per ASTM B253 followed by copper flash; corrosion resistant steels and nickel and cobalt alloys or other basis metals may use a nickel or copper flash undercoat when the purchaser permits. Electroless Nickel Preparation: Parts having a hardness higher than 40 RC and have been machined or ground after heat treatment shall be suitably stress-relieved before cleaning and plating. After treatment, parts having a hardness of 33 RC and over shall be heated to 375 ± 15 ° F (190.5 ± 8.5 ° C) for 3 hours. If such treatment is injurious to the parts, bake at 275 ± 15 ° F (135 ± 8.5 ° C) for 4 hours. Electroless Nickel, Low-Phosphorous, Note: If permitted by drawing, the maximum hardness and wear resistance are obtained by heating parts for 30–60 minutes, prefer- ably in an inert atmosphere, at 750 ° F ± 15 ° F (399 ± 8 ° C) except aluminum parts shall be baked at 450 ± 15 ° F (231.5 ± 8.5 ° C) for 4 hours. If such heating is not specified, bake at 375 ± 15 ° F (190.5 ± 8.5 ° C) for 3 hours. If this treatment is injurious to parts or assemblies, bake at 275 ° F (135 ° C) for 5 hours. Plating: nickel-thallium-boron (Electroless Deposition) and nickel-boron (Electroless Deposition) Preparation: All fabrication-type operations shall be completed. Post-treatment: Cold-worked or heat-treated parts and aluminum alloys and other parts requiring special thermal treatment shall be post treated as agreed upon by purchaser and vendor. Other plated parts within 4 hours after plating shall be heat treated for 90 ± 10 minutes at 675 ° F ± 15 ° F (357.5 ± 8.5 ° C).
Copyright 2020, Industrial Press, Inc.
ebooks.industrialpress.com
Made with FlippingBook - Share PDF online