Media That Stays Sharp
Is there a sharp, preformed ceramic media shape that can reach into tight-radius areas of parts?
Q. Our company produces a cosmetic aluminum fitting. We vibratory finish with a ceramic media to produce a uniform finish. The media do not reach into the tight radius of the part’s external corners, leaving a brighter finish in the unprocessed areas. Is there a sharp, preformed media shape that can reach into these tight radius areas? —M.K.
A. The ¾" × 1" polyester or synthetic plastic wedge (bowtie) works well in processing tight external corner areas.
The plastic wedge is the only preformed media type and shape I’ve found that sharpens as it wears. In contrast, ceramic media may start sharp but round as they wear. Using wedge plastic media is a more stable process than the ceramic process.
Your vibratory process time cycle will have to be increased to allow media to reach into the tight area, however.
It has been shown that the inexpensive chemically accelerated vibratory surface finishing (CAVSF) process can reduce the average surface roughness.
Advances in equipment, automation and consumables can help you compete.
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 ASTM A480-12 and EN10088-2 are two; BS 1449-2 (1983) is still available, although no longer active.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