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Electropolishing, Passivating, and Polishing of sanitary fittings

I am having trouble electropolishing my parts. I machine them to under 10ra. Yes, I machine them to that. I never have to mechanically polish the bore of my parts afterwards. Once they are finished being machined, I clean them in a degreaser and ship them to my electropolisher. When they return to me the ra typically increases at least 5 ra. Resulting in a bore of 15ra, which is the opposite of what I expected. My parts are very nice to begin with, I use high quality, domestic, 316L stainless steel. When the parts come back from the electropolosher, they are hazy, and look worse than when they were sent out. I would love to hear some suggestions on what I can do to sustain the nice finish of my parts while they undergo the electropolishing process. In my situation, should I consider just passivating my parts instead of electropolishing? Thank you. Your help is appreciated.

Joe Howard
Sanitary Fitting manufacturer - Gilford, New Hampshire
2007

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2007

No matter how bright, shiny, and perfect a mechanically finished surface is, it is a plowed field when examined at sufficient magnification, Joe. Complete with clods that can break off, 'dirt' plowed under, etc. In contrast, an electropolished surface is a calm sea. So, for sanitary applications, electropolishing is vital.

It is not too uncommon for an electropolished surface to not match the reflectivity it had before electropolishing. This is not to say that the electropolishing you are getting is satisfactory, though; I think you need to talk to other electropolishers and see if they can do better. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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Thank you very much for the response. We have determined that the problem was in the electropolishing end of things. We have since found a way to ep the parts without getting a hazy or rougher finishes. We looked at a bunch of different issues, the most important were the amperage, time, and purity of the solution. We are now producing mirror like results. I appreciate your help in this matter.

Regards,

Joe Howard
- Gilford, New Hampshire
December 19, 2008