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Ra 0.4 finishing requirement for small part of tool steel

 

I have a very small cylindrical part, about 3mm in diameter and 2mm high. Material is tool steel (D-2). Need to get the surface finish to Ra 0.4(metric). Besides having the whole part grind, I would like to turn it out and then employ a final finishing process. Problem is what is the best means to do it? Tried tumbling, but results are not good enough. Also tried electro-polishing, the person told me that this material will turn to a dark colour as it is magnetic. Is that true? Any suggestion as to how I can get the finish I want?

Thanks,

Ting Teck Beng
- Singapore

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We have polished parts as small as .030 in size in vibratory equipment. It is a slow process using treated dry organic media. It is possible to get 8-10 RMS finishes with this process in about 24 to 72 hrs (depending on what the surface finish is prior to process); however, for anything finer, you may have to go to the old fashion barrel system after vibratory for another 3 to 5 days. High energy barrel systems might be able to achieve results in 8 hours.

AF Kenton
retired business owner - Hatboro, Pennsylvania