I now have a customer who wants CRS sheet metal with 12 openings, round and square, to be painted. The openings should be within +0.003/–0.002 inches after painting. Can this process hold this tolerance?
Q. We started about a year ago painting with powder coating, and I now have a customer who wants CRS sheet metal with 12 openings, round and square, to be painted. The openings should be within +0.003/–0.002 inches after painting. Can this process hold this tolerance? If it can, how can I achieve it? I’m using textured paint. J.O.
A. Textured powder coatings are typically applied at thickness of 3–5 mils. This is thicker than smooth powder coatings (1.5–3 mils) because the texture will not develop at thinner film builds.
Therefore, you will not be able to meet the stated tolerance unless you punch the holes bigger to accommodate the powder coating you are applying. Of course, if the customer does not care if the holes are coated, you can always mask them to prevent any coating from closing them up.
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.
Question: I’ve been told that a powder coated part cannot be “touched-up.” I have some patio furniture that I had powder coated and the powder coating shop that did the work for me stripped the threads in holes used to rack the part.
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