Electropolish 202 & 304 stainless steel Q&A

A. Dear Vibhor:

Giving all the information you ask is a huge task but I will try to give you some answers that may help you.

The cost of electro-polishing depends upon many factors that only you can answer. The first step is to keep good records of your costs and the number and size of your parts. I suggest that you spend a little time with your accountant discussing these issues. Without good records your accountant can only guess at what your true costs are and it may take you many months to achieve your objective.

Sludge will form at the bottom of the tank over a period of time. If it is not causing you a problem then leave it alone until you change your chemicals. In a simple system such as yours, running craft items, tank cleaning will not improve the quality of the electro-polish enough to show any profit.

When to change your acid? That is a good question. I have processes that require me to change the acid when it reaches an iron concentration of 2% and I have associates that leave it until it reaches 5.5%. If you are getting the quality you want in a reasonable time then why change the acid? If your run times are too long and your quality is not what it should be then it may be time to change the acid.

As for changing the formula. I advise against it unless you want to do it properly and run many, many experiments to determine what will produce the best results. I think that fresh acid will spice up your production and improve your quality more than experiments with different formulae.

Good luck,

A. Both 202 and 304 stainless steels can be processed with the same electrolyte, which should be based on a mixture of sulfuric and ortho-phosphoric acids. Your mixture of 80/20 should be OK if they are the correct grade of acids and if you have the correct operating conditions. You do not give your process details, so we can only guess you are using the optimum ones. In the long run, it may be better to use a proprietary solution, as they contain other additives that prolong the life of the solution; they also provide detailed operating conditions, which will vary as the amount of dissolved metal in the bath increases. Making your own solutions is very good for one-off jobs, but to do it on a commercial basis is often a false economy.

A. Your solution should work, for best working results your tank temperature should be between 130-150 °F.
Now your 'whiteish layers' maybe be caused by an imbalance of your specific gravity which should be between 1.70 and 1.78. Don't forget to make sure that you have good electrical contacts on all racks and cathodes.

A. Hi Bilal. I am not personally aware of satisfactory "bright dip" / "Chemical polish" for stainless steel, and I think you might be better off looking into "electropolishing" (we have countless threads on that topic if you search the site).

Regards,

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Ed. update note Nov. 2020: See entry below by Anna Berkovich regarding proprietary non-electric bright dip.

A. Hi, Abhishek. Yes, electropolishing is certainly available for stainless steel utensils. It is a smoothing and polishing process that would last essentially forever, except that a consumer can, of course, scratch the utensil regardless of whether it is mechanically polished, electropolished, or unpolished. Copper plating or bronze plating could last many decades or could wear off rather quickly depending on its thickness and quality. I have 60-year-old RevereWare copper-bottom pots that were manufactured by electroplating with copper.

But as for how to do these three different processes, and the chemicals and machinery involved, it's complicated and you'll have to take one problem at a time and commit to reading a lot of info whether here or elsewhere. Whole library shelves are devoted to each of the subjects you mentioned.

Regards,

THANK YOU MR. TED
IT WAS NICE SEEING YOUR PROMT REPLY.
WE MANUFACTURE STEEL PLATE USING DOUBLE ACTION POWER PRESS, AND THEN FOLD CORNER IN SPINNING MACHINE.

THANK YOU ONCE AGAIN TED SIR; IT WAS REAL NICE SEEING YOUR GOOD RESPONSE.

A. Hi Paresh. H2O2 rapidly decomposes unless special stabilizers are added, and chlorides are murder to stainless steel, so I don't think it's a good idea to use that bright dip. Sorry, I am not personally aware of "bright dips" for stainless steel.

Regards,

adv.
We have installed the Brite Dip chemical processing for stainless steel in two locations - in USA and in Italy. The electrolyte does not contain HCl or hydrogen peroxide.

A. Hi Amit. If the material is the same, the problem is probably insufficient current density. You need sufficient current to move out of the etching range and into the electropolishing range. You cannot make up for it with longer processing time. Bigger wire needs more amperage! Good luck.

Regards,

A. Hi Amit. See thread 44029, "Analysis of metals & acids in Electropolishing Baths for stainless steel" ...
But we want no abandoned shopping carts (of questions) on this site, and you didn't acknowledge the answer to your previous question on wire electropolishing :-)
Please respond to/ resolve that other discussion before moving on. Thanks! Good luck.

Regards,