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We are manufacturers of various types of locks. ex.Pad locks ( lever & pin cylinder ), door locks. mortise locks, Ultra key & pin cylinder locks. safe deposit locks & door accessories like brass, Black nickel & Golden finished handle cover plates, etc. One of our largest volume & fastest moving product is Multi purpose Furniture lock. We produce apprs. 2,50,000 nos. of this lock per month. The body of this lock is a die casted mazak component. This body get clinched around its periphery after inserting the cylinder & bolt. During this clinching operation we face problem of body cracking & powder coating peeling off at the periphery area only.

Kindly suggest some remedy to overcome this problem.

Yatin D Vichare
- Mumbai, MAharastra, India


Without actually seeing the part, I will offer my guess as to the problem. When the powder coating is applied, the normal electrostatics tend to apply the powder to the closest ground. That is how you get wrap around and what is called "edge build". Just about any powder coated substrate will show this edge build. The powder companies formulate each different powder chemistry to meet a certain specification. They in turn give you a product specification sheet in which you can physically test your part against. Assuming you have proper pretreatment, if you follow the powder manufacturers application specifications, you will be able to adequately perform and pass the product specification sheet. The problem comes when you have areas such as edge build. If the product specification sheet calls for the powder to be applied at 2-3 mils to pass the test provided on the sheet, you may have 5-6 on the edge, which puts you out of process. Anytime you stray from the powder manufacturers specifications, detriment of the topcoat exists as is probably true in your case. The edge build if true, could not take the pressure caused by your manufacturing process. Try looking at less powder being applied to some and see if it eliminates the problem.

bob utech
Bob Utech
Benson, Minnesota

A Guide to High Performance Powder Coating
by Bob Utech
[link is to Amazon]

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