Letter 18495

Electro-polishing [Illinois]  

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Trying to find the chemical makeup of a solution for electro-polishing of stainless steel, carbon steel, and aluminum.

Merlin Milligan
- Somonauk, IL

Many electropolishing solutions contain phosphoric and sulfuric acids. Various formulas are given in the in the Metal Finishing Guidebook article on Electropolishing

There are many vendors with proprietary solutions; this is a good way to begin as you get the correct solutions and procedures for your particular alloy(s). Also, they will advise as to the most suitable alloys and run sample parts. Click the Chemicals link below, then search for electropolish. At least one of these vendors has a non-environmentally hazardous product.

Ken Vlach - Goleta, California

I would like to recommend the following formulation to u: Glycolic acid 55%, sulfuric acid 30%, water 15%. the formula is free of phosphate and absolutely environment friendly. Of coz you can obtain excellent result.

Benlogo G.B. Huang
- Guangzhou, China

Hi Nick

It seems that due to an locally high concentration of one of the SS316L elements, that area is more active then the other. The comet shape you described is a result of gas bubbles formed at the active area.

You may try to reduce voltage (current) or circulate the acid so gas bubbles will evacuate rapidly from surface.

By the way, which polishing acid do you use?

Oded

Oded Nissan
- Neve Ilan, ISRAEL

Dear Adviser,

As I could determine from your site, you are interested to support people to find a good and environmental friendly process to electropolish metal parts.

I am a retired Chem. Engineer and am trying to electropolish some machine parts made of stainless steel AISI 304 and AISI 316 to improve surfaces for sanitary use.

I never did electropolishing by myself and want to try it in my garage before to launch any service operation. Could you be of any help giving me some adequate formulation for this task? What also could be a good DC voltage to induce the controlled corrosion of the peaks at metal surface?

Best Regards,

Herbert F. Steffen
- São Paulo, SP, Brasil

What could be a good DC voltage be to electropolish stainless steel?

pieter coetzer
active fleet - durdan sa

Things are, I'm sure, different in Brasil than the U.S., Herbert. But the idea of running a process like electropolishing in a garage is a very dangerous one.

Pieter, if you don't find the guidance you seek in the previously mentioned article in the previously mentioned Metal Finishing Guidebook, there is a great chapter on electropolishing in the Electroplating Engineering Handbook.

Merlin, to my knowledge carbon steel cannot be electropolished.

Ted Mooney, P.E.  finishing.com Brick, NJ

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