Metal Finishing Guide Book


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earlier, processing trials. However, by asking the right questions, media selection becomes easier: What is the desired surface finish? Aggressive deburring on steel parts requires a different media than���for example���a surface smoothing application on aluminum parts. In the first case, a relatively ���fast-cutting,��� large-sized ceramic media may be required, whereas in the latter a ���fine-grinding,��� small to mid-sized plastic media may be needed. What is the desired wear rate? All vibratory finishing media wear! Of course, you want to select the media that will do the job at the lowest possible wear rate and, thus, cost! Can chipping of the media be an issue? If media chipping is an issue, ceramic media usually is not an option. What about separation of parts and media? After the finishing process, the finished parts must be separated from the media. With ferrous steel parts, magnetic separation may be an option. Otherwise, there must be a distinct difference in size between parts and media to allow separation by vibratory screening. And what of media lodging? Depending on the part geometry and size, media lodging may be an issue. By selecting the right media size and shape, media lodging in the parts may be minimized or altogether prevented. Last but not least: How about media color? If lodging cannot be prevented, the media should at least have a bright color so that lodged media can be easily detected and removed from the part. THE CORRECT MEDIA CHOICE MAKES ALL THE DIFFERENCE Vibratory finishing media may not be the most exciting subject to talk about��� unless you are infected by the mass finishing virus! But considering the consequences of the wrong media choice���poor surface finish, high scrap rate, and lots of rework (all of this associated with high cost) ���for the user of mechanical surface finishing it is definitely worthwhile to pay a bit more attention to this subject. Hopefully, this article was able to shed some light on the various factors that need to be considered in the selection of vibratory finishing media for a specific surface finishing task. 17

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