Need a Different Mass Finishing Method
I have 4,000 parts/day of a flat stamping, much like a large flat washer. The problem is that the parts stick together and many of them only get finished on one side. What are your suggestions?
Q. I have 4,000 parts/day of a flat stamping, much like a large flat washer. The part is 3 x 0.150 inches. I use round vibratory finishing equipment with ceramic media. Finishing only takes 10 min. The problem is that the parts stick together and many of them only get finished on one side. I have tried adding small media such as glass beads, or sand, and it was not successful enough to eliminate inspecting and sorting, and the residue caused additional problems with my compound filtration and recirculation system. One company suggested a multi-pass vibratory machine. Parts could be fed in slowly enough that they would stay apart during the process, but the investment is very large for this equipment, and I don’t favor buying used equipment. What are your suggestions? H.G.
A. The pros and cons of a multi-pass machine can be argued at another time because it isn’t a good answer to your problem, given the small volume of parts. The flat washer people for years have used open-end tumblers, similar in appearance to a cement mixer. They tumble without media—a very low cost process. The downside is that the parts impinge each other and you get a dented surface. You told me you couldn’t accept that finish. Neither can some of the flat washer people. This has led some in that industry to change to centrifugal disc finishing. It can be done either part-on-part or with media. The action in these machines continuously slides the pieces apart, and I believe it will work for you. I recommend, as always, a production load demonstration.
Surface finish types for commercially supplied stainless steel sheet are detailed in various standards. ASTM A480-12 and EN10088-2 are two; BS 1449-2 (1983) is still available, although no longer active. These standards are very similar in that they define eight grades of surface finish for stainless steel. Grade 7 is “buff polished,” while the highest polish—the so-called mirror polish—is designated Grade 8
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