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Remove Titanium Wire EDM recast layer

2005

My company needs to set up a finishing operation to remove the recast layer on titanium parts after they have been wire cut on an edm. This is something we would not do very often so I am looking for something inexpensive and simple. I have been reading information on the internet and would go with the process of pickling to accomplish this. I don't know much about chemicals and need to know what mixture of chemicals are needed.
Is pickling the best method?
Is this something that can be easily do in a job type machine shop?

Byron Newton
Machine Shop - Athens, Alabama

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Step one would probably tinker with the EDM parameters to reduce the recast layer as it can be difficult to remove.
Typical pickles for titanium are nitric and hydrofluoric acid mixtures. The HF is extremely dangerous to use and can be decently replaced with ammonium bifluoride. A large problem with pickles is it tends to attack the parent metal faster than the recast layer because of the oxides in it. If it were my shop, I would look at trying different grits of grit blasting. A lot of time spent on hand operations, but is compensated by less capital and a huge increase in safety and less liability. Also, no tanks to corrode all of the electronics in the shop. PS, it takes a lab to control the tanks.

James Watts
- Navarre, Florida
2005