Q. How can we reduce or minimize nesting of parts in our barrel plating operation? Racking of the parts is not feasible economically, and the high reject rate from parts nesting together during barrel plating is not acceptable. —B.T.
A. This problem crops up often. The solution today is the same as it was when I first answered this question years ago:
The problem of nesting in barrel plating is essentially a mechanical problem. A number of different methods can be tried to minimize the problem. You can sometimes mix two different parts together in the plating barrel, but the drawback to this method is that the parts must be separated after the plating process.
Another approach is to add steel balls or very small parts to the barrel load. These small parts can be separated from the rest of the barrel load by screening.
Sometimes something as simple as reducing the size of the barrel load will help.
The best solution is usually the hardest to implement: The parts can be redesigned to include one or more dimples on them. If these dimples are placed in the right locations, the parts will not nest. Of course persuading your customer to redesign his parts so that the barrel plating process is less prone to nesting is not an easy task.
Masking is employed in most any metal finishing operation where only a specifically defined area of the surface of a part must be exposed to a process. Conversely, masking may be employed on a surface where treatment is either not required or must be avoided. This article covers the many aspects of masking for metal finishing, including applications, methods and the various types of masking employed.
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