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Titanium

Titanium

Titanium

(OP)
I want to obtain, and machine Titanium 6Al-4v on standard lathe and mill. . The final product will be a con rod for my racing BSA. Helpfull advice will be appreciated.
Thank you in advance
Craig Peach

RE: Titanium

Don't know about feed rates and tooling, but titanium fines are flammable/explosion hazard so incorporate measures to collect and contain titanium dust.  

RE: Titanium

I would be careful machining a conrod.  The grain dirctions on a machined part are not suitable for the high cycle loads a conrod experiences.  The most suitable method would be to drop a conrod fromm light aluminium alloy taking note of the S-N curve and noting the fatigue life.  Machine and polish final forging to extend fatigue life.  Also consider shot peening surface for further fatigue resistance.

Nigel Waterhouse
n_a_waterhouse@hotmail.com

A licensed aircraft mechanic and graduate engineer. Attended university in England and graduated in 1996. Currenty,living in British Columbia,Canada, working as a design engineer responsible for aircraft mods and STC's.

RE: Titanium

Obviously when dealing with recipricating components, mass is a crucial issue, hence light alloy.  Unfortunately, light alloys have a finite fatigue life.  You can calulate this.  You will need the S-N curve for the material, the max' stress in the conrod and the frequency of the cyclic stress, which you will know from the RPM.

I would not recomend machining a light alloy conrod.  You will have problems.  I would say your most at risk area is around the gudgeon pin, big end bolt holes and the flanges of the I section.  As you are a skilled machinist, I would advise you to make inquiries at a press forging facility.  Get the spec' on the forging pattern they would need, make that yourself, and see if they can do the pressing for you.  Maybe you could come to an arrangement with publicity at the race meets to help compensate them for there time.

Nigel Waterhouse
n_a_waterhouse@hotmail.com

A licensed aircraft mechanic and graduate engineer. Attended university in England and graduated in 1996. Currenty,living in British Columbia,Canada, working as a design engineer responsible for aircraft mods and STC's.

RE: Titanium

Craig,

Take heed of the warnings you've gotten.  Manual machining of Ti is difficult because it LOVES to be climb milled.  That's RISKY on all but the best manual machines.

Also, DWELLING during the cut is a BAD thing.  All sorts of surface effects happen.  That not only makes the next cut difficult and a bit unpredictable, it changes the stress factors too.

All the sexy parts in Ti these days are CNC machined - they don't dwell.  All the sexy Aerospace parts have been made by hydraulic tracers or early NC machines.  (NC's have been around since the mid 40's in defense business.)

Larry

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