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Finishing Fallout

As a Quality Professional of 35 years, I have come across various finishing operations done subsequent to manufacture. In each type of finishing operation, each & every Finisher seems to have their own Fallout % that we, the manufacturer, is suppose to "Allow" for. While I do indeed understand some of this "Tribal" knowledge is based on degree of experience, type of finishing, etc., isn't there some guidelines? For example, Rubber Bonders need 10%, platers need 5 % for parts over 2 sq. feet surface, 10 % for smaller parts, vibra & tumblers need 1%, etc. Is there any uniform guidelines that are used? I am hard put to believe that an Industry that has been in existence for Hundreds of years hasn't come up with some Standard. But then again, maybe we Quality Professionals aren't being paranoid in thinking the Finishing Industry is keeping it a Secret!

Sharen A Gutierrez
stampings - Stratford, Connecticut, USA
2007

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The standard terms in the contracts are in fact usually negotiable, Sharen. On the other hand, 100 percent satisfactory parts is usually impossible, and often not within the control of the plating shop. So that's what brings us to where we are. While 5 to 10 percent fallout would be very high for most plating shops for most types of parts, consider this hypothetical case:

You ship zinc diecast parts to a plating shop. Diecast parts with cold shuts cannot be successfully plated because the process solutions will wick into those miniscule cracks. What would you have the plating shop do? Some of those parts with cold shuts probably could have been salvaged if vacuum impregnated before they started, but have you allowed for that cost, or do you leave it up to the shop to decide which way to quote?

The fact is, if you very carefully inspected the diecast parts before shipping, and you allowed for the cost of vacuum impregnation, you can probably approach a zero percent fallout at a high quality plating shop. But if you don't rigorously inspect the parts, and no allowance has been made for vacuum impregnation, a fallout of 10% and more will probably happen at the very best plating shops because 10% and more of diecast parts will often be unplateable.

I believe the right approach is to visit the plating shops, sit down with them, and work together to figure it all out. But if you treat plating of your parts as a commodity, while the parts you ship are variable in their plateability, you can't get to a consistent fallout level no matter how hard the plating shop works. Best of luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007