How to polish titanium to mirror like finish

letter 53054

September 9, 2009

I am a Manufacturing Engineer working at a company who's primary product is titanium rods. We centerless grind them to surface finishes better then Ra.05. We have a customer who wishes there to be no microscopic scratches even though the surface finish meets the requirement. This is a very subjective visual requirement and we are having trouble achieving this. Any help would be greatly appreciated

Mark Dane
Engineer - Valencia, California

Hmmmm. I'm not sure how long these rods are; however, if you are centerless grinding they must be long. Therefore, it sounds as if a pass through wheel system would be doable using non-woven wheels. You might be able to attach this to your centerless grinder. Then again my experience says there still may be porosity in the rods due to the nature of the material and/or processing

AF Kenton Nova Finishing Systems Inc. Huntingdon Valley, PA

Just so you don't try it I once made a batch of Remington 700 firing pins out of titanium for a police force. The cops had some hair brained idea that a super duper polish might improve the lock time slightly.
I tried to polish them using a hard 4 inch felt wheel on the tool post grinder with the firing pin running between centers on the lathe. I tried rouge, matchless rouge, matchless diamond, Tripoli, Polish-O-Ray 555 and a host of other grease, greaseless and wax base polishes. It was an absolute disaster.
The pins were 6 inches long and ¼ inch in diameter. As the wheel got close to the center of the pin the drag of the polish would suck the pin into the wheel and when completed my firing pins looked like hour glasses. (exaggeration)
No matter how little or how much pressure I put on the wheel the same thing happened. I rose the center of the wheel. Lowered the center. Reversed the direction of the wheel. Reversed the direction of the lathe. Altered the feeds and speeds six ways from Sunday. All I did was blow two days and about 6 feet of titanium. The best I ever got was using crocus cloth by hand with water and dish soap. STUPID COPS ! :o(

Rod Henrickson     gunsmith Edmonton, Alberta, Canada

You May be able to do this in a high energy finishing machine like the ones MFI make.

Gary Groshel
- Edina, Minnesota

What is the high-energy machine? Are you talking about high-voltage plasma polishing?

See picture of the medical implant polished by such method. However it is not economically visible to polish rods by such method. How long is the rod?

  

We have less energy consuming electrochemical processes for bigger parts. What are the requirements to the surface quality?

Anna Berkovich Russamer Lab Pittsburgh, Pennsylvania