Letter 13254

Chrome plating titanium 

I wish to experiment with the use of titanium for use as a crankshaft in an experimental lightweight engine. I understand that titanium will not run in conventional bearing material, so I need to plate the crankshaft bearing journals with hard chrome. Does anyone have information on the plating process, or any other coating?

Stuart Pearson
- Christchurch, New Zealand

There are procedures for plating titanium listed in ASMI's Metals Handbook, vol. 5, Surface Engineering. But I am told by someone who knows more about it than me, that the only way you'll really plate titanium successfully is to nickel plate it and then heat it hot enough for the nickel to diffuse into the titanium. There is an ASTM standard for this.

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

I had a crankshaft chrome plated for an expermentel 65 hp engine orginially produced by continental. It was .020 undersized and plating brought it back to standard. After 500 hrs of use the crankshaft was in perfect shape and oil analysis showed no wear at all. I had it done by a company in Milford Delaware. The cost was minimun compared to the cost of a standard crankshaft. this method can only be used in non certified engines as I have been unable to find any approval for it for certified engines. I got the idea from a very old military maintenance manual where it was used for round engine cranks. I figured if it could handle the stress of a round engine than it should be fine for an engine turning only 2300.00

David Henderson
- Rehoboth Beach, DE, USA

Thanks, David. The chrome platers on this forum will be happy to hear of your satisfaction. However, unless you tell us otherwise, I have to doubt that your crankshaft was titanium, and must note that successfully plating a titanium crankshaft is an awful lot harder than plating a steel one.

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

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