cutting a taper on titanium rod

[marty7001]

I am cuttting a 3.5 " taper 0.217" to 0.055 on a titanium rod. I am having a little trouble doing this, mainly dealing with the flex. I am new at working with titanium. Any suggestions or general comments about working with titanium will be much appreciated.

Thank you
Marty

[NC Cams]

Which alloy????

Investigate the recommended cutting feeds and speeds - ditto that of the cutter inserts.

IF you don't CUT titanium, it will work harden and become VERY difficult to cut.

IF you get it too hot, it tends to oxidize (titanium oxide - same stuff used on sand paper) which makes it hard and brittle.

Speeds and feeds are REAL critical. I'd check with your Valenite distritutor - their tech support staff can/will recommend tools, speeds and feeds.

Just be sure you know what alloy you're dealing with when you call.....

[WhiteTiger]

The only means I know of for acceptably turning a taper that is 10 or more diameters long and involving more than .5 diameter reduction is to take it in steps.

For this one I'd cut it in not more than half inch step lengths. Make only your first cut to true diameter and leave a couple thou oversize on all the rest. I usually make a support spud to fit between the tailstock livecenter and the small end of the workpiece. Just a short piece of stock center drilled on both ends then drilled through. In place it gives enough support to the free end to allow final cut to dimension full length.

Still probably be a lot of fiddling and trial and error though. I never used the method to cut a taper that long, and with that much reduction on a piece of stock that small a diameter.

This is the sort of job that in production would only have around half or two thirds of the material removed by turning and then would be finished with centerless grinding. Tough job for a pure lathe operation.



Tiger

[One of Many]

Originally Posted by marty7001 I am cuttting a 3.5 " taper 0.217" to 0.055 on a titanium rod. I am having a little trouble doing this, mainly dealing with the flex. I am new at working with titanium. Any suggestions or general comments about working with titanium will be much appreciated. Thank you Marty

What you might consider is a pull chuck in the tail stock. This is a live center, but with bearing mounted drill chuck or other gripping fixture that can grab a portion of excess end material while giving a little tension to your stock. As long as it is just taught enough to turn with minimal flex, your part can be made. It does take some sharp cutters that also minimize cutting pressures and reduced feeds, but it does work. Shielded bearings have less friction than sealed, so this can help if they can be protected to some degree.

Titanium is like Stainless Steel in some respects. Do not let the cutter dwell or it will work harden. Keep the chip load going with a good sharp edge.

DC

[marty7001]

It has been a long time ago, but I did make a pull chuck and it helped alot. Thanks for the idea.

Marty