How to polish a circular o-ring surface at aluminum for vacuum chamber

Currently I face up a problem to get the circular surface for o-ring use in high vacuum chamber. The circular sized about Ø40mm.
I have tried to use scotch brite (fine grade), but what I get is some minor circular line appear on the surface.
Do there any way to perform this ?
thanks.

Lymun Lai
Process Enginer - Penang, Malaysia
November 16, 2009

Scotch brite is a 3M product that different divisions make different grades with similar names, so it greatly depends on which one that you are using. Industrial white is the finest that I remember.
You may have to go to diamond paste or one or a series of metallurgical aluminum oxide powders(paste) to get what you want. You might be able to use a wood burnishing stick with the abrasives or you might end up using a brass or similar one. Talk to someone that does mold mfg/repair on how to do it.

James Watts
- Navarre, Florida
November 18, 2009

I am concerned that you are dealing with metal and a O ring application. Normally that surface finishing must be done in a specific manner. Meaning that any surface finishing must be done to orient the finishing lines in the direction of the sealing material. This orientation acts as a barrier against leakage.

AF Kenton
retired business owner - Hatboro, Pennsylvania
December 11, 2009

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