See if this helps you out a little
Has anybody machined in TZM? We have been working on a job this week that seems impossible. After three days we got a good surface with regular turning but the external thread is awful and the grooving tool lasts for one part only. We have ran out of ideas?
So what's this stuff like? Is thread milling a possiblity on this job? Have you tried various coolants, etc? What about this new thing I read about lately, using a stream of liquid nitrogen on the tool tip? Maybe extreme cold would help?
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
I've seen and studied that site Kmed. According to it the stuff should be machinable. We have tried almost everything. Dry machining, oil and regular coolant. Same result, bad surface finish and very short tool life. High speed, low speed, high feed, low feed, carbide, hss, diamond tooling. Same result, bad surface finish. We even tried to mill the part. That too gave the same result. The only thing giving acceptable result was to have a wide grooving tool to cut the diameter in steps.
But the very small grooves in the part, the short tool life and the impossible thread made us give up. I think that the best thing might be to grind the part. Roll threading might work also.
The stuff is not particularly hard and the chips are very short since it is a sintered material. It seems somehow that particles comes loose from the work piece very easy but then starts to roll or smear between the tool and the part, causing the tools to wear and the surface to look bad.
I don't think this applies here since TZM is rather soft. But thanks anyway.
I have never found the magic way to machine TZM easy.
Wire EDM probably works the best. But, only use rough cut.
You will not be able to use skim cuts and get a good finish.
Wire EDM is only for sections up to 2". Thicker than that you
probably won't have success. Forget plunge EDM unless it is a
very small area. It takes more electrodes than you can imagine.
For milling I use carbide with a corner radius. They don't last very long.
For grinding you have to have coolant and a lot of time.
Thank you for replying but that was almost six years ago. We had to turn down that job finally. We didn't find any way to machine the material to the specs on the drawing.