Electropolishing titanium. Formula and method.

A. Hello Billy.

The metal finishing industry is highly regulated environmentally; in fact it was the nation's first categorically regulated industry. This means that you need to apply for discharge permits, keep track of waste accumulation dates, etc. For this reason and others, the metal finishing industry is extremely jobshop oriented, and most manufacturers subcontract their electropolishing needs. This is not to say that you can't install an electropolishing system -- only that there is an alternative you may not have considered yet.

Generally, an electropolishing system is not called a machine because it is not a packaged entity but a bunch of tanks, a separate ventilation system, maybe a transport mechanism, a wastewater treatment system, and various heating, cooling, air agitation, and purification accessories. I am not challenging your grammar, just trying to help by conveying the idea that the operation is more process oriented than machine oriented. It's rather like the idea that a brewery doesn't make beer by buying a beer brewing machine. The general electropolishing process is explained in several plating textbooks including the Electroplating Engineering Handbook [on AbeBooks or eBay or Amazon affil links] , the Metal Finishing Guidebook, and ASM's Metals Handbook Vol. 5.

Good luck.

A. Electropolish requires excellent connections to avoid arcing damage to the part. Your part is small, so would require a fair amount of rack setup time. Are you locked into electropolish to the point that a mass finishing system would not suffice? There is at least one vendor at this site that specializes in electropolish and may have something for titanium. Note that it is a tiny fraction of SS that is electropolished, so may not have a lot of vendors in that branch of the field.

A. Billy,

adv.
Russamer Lab manufactures such equipment for titanium electropolishing and sell this process and equipment to the shops. The process is environmentally safe since titanium is electropolished in salts, not acid. It takes about few minutes to polish titanium medical parts by our high-voltage equipment. This process is good for small parts since a lot of power is required.

However we are experimenting with low-voltage titanium polishing, which is good for big parts (also environmentally safe). Some of the titanium alloy are polished quite well. We have discovered this method accidentally while testing environmentally safe method of polishing large nickel surfaces. Anyway, in order to suggest one or another method, we need to test samples and hear all the requirements.

Environmentally safe-- Semantics! The acids used in other electropolishing can be neutralized by "elementary neutralization" with little or no grief from the environmental folks. To my failing memory, Ti and vanadium are not regulated wastes. The aluminum in 6-4 is, after it reaches a level of around 30 ppm. The real killer to electropolishing waste is the copper from the racks. This puts it squarely into a regulated waste. Anna's "salts" may not start out as regulated (as acids are, but they will end up being regulated when they have enough aluminum or copper or any other regulated metal. Other than the high voltage, it sounds like their process is a lot more operator friendly and highly probable of less air quality problems than the warm acid bath with lots of outgassing.

A. Chemical polishing of titanium:

60-62% Perhydrol(Hydrogen peroxide)
8-10% Hydrofluoric acid
30-31% water
temp. 20 °C, 30-60 min.

Good luck!

A. The method you suggest is damaging for the environment and workers.

adv.
There is a proprietary method of polishing titanium in saline-based solution. Contact us if interested.

A. Hi Calvin. One thing I can tell you is that your company is right in eschewing perchloric acid ... which was responsible for the worst metal finishing accident in U.S. history (see letter 9408). Good luck.

Regards,