Friday, August 8, 2008

Preparation for Plating

Cleaning is one of the final steps in preparing a metal surface for plating. Preceding steps of fabrication, stamping, grinding, polishing, buffing, handling and shipping have each contributed to the surface finish and to the soft that must be removed to obtain a satisfactory electroplate.

Lyons has summarized the objectives of cleaning before electroplating as follows. “In electro deposition, a surface is required which will receive a smooth, adherent metal deposit, but is not necessary an absolutely clean surface. In general, an acceptable surface is one on which objectionable surface films have been replaced by films more suitable and acceptable for electroplating”.

Current recommended reference for this purpose are Metal Finishing Guidebook, Metals Handbook, Volume II, Heat Treating, Cleaning and Finishing, and Electroplating Engineering Handbook, edited by A.K. Graham. Reference 5 to 9 cover recommended method and procedures.

In addition to the presence of natural oxide films and normal shop soil on metal parts, the finishing department will receive parts soiled with heat scale, quenching oil, rust proofing oil, drawing oil, stamping lubricants, and even zinc phosphate coatings. Hence, the soil to be removed before electroplating can be a very complex mixture and its condition and ease of removed will change with aging. Two shops will seldom have identical conditions.

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