When preparing to apply a plated finish, the first step is to polish until the surface is smooth. Next, some metals require buffing like brass, copper, zinc die castings, and aluminum alloys before electroplating services can be applied. Steel is rarely ever buffed prior to a nickel plating or chrome plating service, due to its high cost. Recently, the use of a bright, high-leveling ductile acid copper plating bath or a high-leveling bright nickel bath almost completely eliminates the amount of buffing needed to produce a lustrous finish.

Buffing and Polishing

A metal’s surface condition can profoundly effect the overall performance of the nickel plating. Preparation for nickel plating begins with the manufacturing of the base metal. Blow holes, rolling scams, and slag and sand inclusions can have a substantial effect on the quality of the nickel plating. Moreover, the processing techniques that are used on the base metal, which can be administered before or after it has been formed, can have an effect on the porosity of the electroplating.

Generally, data shows that rough grinding is extremely detrimental to the protective capabilities of nickel platings. In addition, rounding off and smoothing out all of the present scratches and flaws were important for enhancing the protective capabilities of the nickel electroplating. For example, with a well lubricated, final polishing wheel, one can buff the base metal, eliminating any remaining slivers or blemishes, and increasing the electroplating service overall protective value.

Pickling and Cleaning

The main purpose of cleaning the base metal prior to plating is to remove any interfering substances present on the surface. Corrosion and adhesion resistance of nickel plating is contingent on the use of an appropriate cleaning cycle. Alloying, or the process of diffusing one metal into another, may be destructive when the added alloy layer is more brittle than the individual metals alone. There are a number of harmful substances that can engender poor adhesion between the base metal and the plating, including oxides, oils, graphite, grease and immersion coating of lead and copper that were exposed to contaminated acid dips.

When cathode cleaners are contaminated with dissolved copper, zinc or led, the electroplater can create a non-adherent film. Poor adhesion can also result when cathodic cleaners are used for longer than 1 minute and there is no occurrence of anodic activation. In other instances, when intermediate electrode effects happen during the electroplating process, poor adhesion can ensue.

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