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Alternative Media for Magnetic Spinner

Hello and thanks for reading my question
I work for a medical manufacturer, and we are trying to polish 305 stainless rings to as bright of a finish as possible. The rings/bands are only .007" thick, so care must be taken to not smash them. The rings are relatively smooth, but a cold working process leaves pronounced witness lines which are undesirable. (This process is entirely aesthetic, it serves no functional purpose for the part.) Lately we have had success by first deburring the bands in ceramic media in a rotary tumbler, then by polishing/burnishing in a magnetic spinner with stainless steel pins. I had heard of ceramic coated magnetic pins for deburring, but I've been unable to find them. The idea is that we could use ceramic or porcelain coated pins instead of tumbling the bands, and thereby save several hours of cycle time, as well as the expense of purchasing more tumblers AND spinners. Is there such a media? If not, what else could be used to "scuff" the surface and eliminate the stretch marks?

Chris Johnson
Mechanical Engineer - Salt Lake City, Utah, United States
April 19, 2011

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#1.Personally I have never heard of ceramic coated pins. Not sure they exist. #2. In any magnetic system you are performing a burnishing operation. That means that you are normally using a harder material with no abrasive qualities to modify the surface of your parts.You will experience work hardening and a possible dimpled appearance. There are some additives that can buffer the parts but they will also affect the media. #3. If you want to play it safe and get the best reflective finish and smoothest finish you should consider using dry organic media. If you need to actually remove marks there is an abrasive mix.

AF Kenton
retired business owner - Hatboro, Pennsylvania
April 25, 2011

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AF-
Thanks for replying to my question. We ended up following your advice and we run the bands in a final dry media polish. We start with a deburr in a wet bowl with ceramic media, then we run the parts in a dry bowl with "green buff" which is an organic polishing media. We had great results, getting parts to a mirror-like finish with no surface defects. Speed was on par with the magnetic spinner.

Chris Johnson
- South Jordan, Utah, USA
June 23, 2011