Q. We have a large quantity of 6063 aluminum extrusions that we are cutting to length (4" × 4" × 6"). This part is sharp and we need to dull the edges for handling. What finishing process do you recommend? —K.S..
A. Vibratory finishing with semi-automatic- or fully automatic-unload vibratory bowls will do the job. De-sharpening the extrusion with ceramic media will take about a 4-6-minute process. This may not completely deburr the part, but it will de-sharpen it for handling.
It’s a matter of selecting a size and shape of ceramic media for your extrusion. The media shape must get into the areas that need de-sharpening while staying out of areas in which it could lodge. The media size should be a different size than the part. This allows part/media separation so the parts can be unloaded from the machine.
The vibratory bowl machine can either be a continuous process that accomplishes the 4-6-minute cycle times or a batch automation process that accommodates the amount of parts required. Both systems can process parts coming straight from the cut-off saw if need be.
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 ASTM A480-12 and EN10088-2 are two; BS 1449-2 (1983) is still available, although no longer active.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
When choosing vibratory media, understand the size, shape, starting roughness condition and metallurgical structure of the part.
It has been shown that the inexpensive chemically accelerated vibratory surface finishing (CAVSF) process can reduce the average surface roughness.