Electrodeposited zinc, or to call the finish by the more well-known name of zinc plating, is traditionally one of the most cost effective methods of protecting iron or steel from corrosion. This method lays a thin film of zinc over the surface to provide sacrificial protection to the underlying substrate. The term sacrificial refers to the way the zinc corrodes in preference to the substrate and so protects the covered steel, it also has the additional benefit that steel exposed at cut or abraded areas will not easily rust.
Zinc plated finishes are normally enhanced by a post-plating conversion coating more commonly known as a passivate. This dip process applies a thin coating onto the surface of the zinc, traditionaly these passivate coating would of contained hexavalent chrome however due to the End of Life of Vehicles (ELV) Directives and Legislation such as Registration, Evaluation and Authorisation of Chemicals (REACH) the Anochrome Group has now replaced all passivates with hexavalent chromium-free coatings. Generally these fall into two categories of trivalent passivate – lightweight or heavyweight – depending upon the finish performance or specification required.
Additional coatings can be added to further improve the salt spray performance or to modify the lubricity of the component or fastener by the addition of top coat torque modifiers. These are available in a range of values to suit the majority of automotive specifications.
Anochrome offers an extensive range of passivates, tops coats and torque modifiers including the following: Lanthane Passivate, Finigard 105, Magni B18, JS500, ELV1500 LT, ELV3000, ELV 5105, ELV Blue, Deltacol GZ, TnT 08, TnT 11, TnT, 12, TnT 15, Gleitmo, A3 Wax
The barrel plating process involves placing the items to be coated in a perforated barrel-shaped cage that is manufactured from nonconductive material. The barrel is then submerged into a series of tanks containing the appropriate chemical solutions, while a slow tumbling action is used to commence the plating action. This is a very cost effective method of coating parts but may not be suitable for large or complex parts.
The rack plating process involves locating the items to be coated on an electrically conductive jig / rack. The rack is then submerged into a series of tanks containing the appropriate chemical solutions, to commence the plating process. This is a more costly option than barrel platings but may be more suitable for large or complex parts.