Tantalum revisited

[cruzila]

I searched a few threads here, but was wondering if anyone has experience with form tapping in Tantalum. I have a big part$$$$$$$ 5-1/2 dia 7/16 thick with lots of hole details.

We cut a lot of titanium here so the milling part should not be too bad to use that as a reference.

[Colin Gilchrist]

Carmex Threadmills

That's my recommendation, instead of tapping.

[David Colin]

I already form tapped in titanium because a standard thread endmill wouldn't fit. I needed a long reach tool for this feature (iso M3 9mm depth close to a pocket wall 60mm height). That worked, with Emuge taps, using tapping oil in every hole however tool life was short (1 tool=20holes). Luckily it was a small batch.

All the way thread milling if you can.

I'm running a job at the moment in titanium TA6V, M3 4mm depth, first tool machined 700 holes and still running (still an Emuge tool).

[WestRiver]

Tantalum is like the softest copper you have ever seen it is nothing like titanium. Just think gummy soft copper.

[cncappsjames]

And it flakes like a MoFo. If you drill thru holes, typically you'll get break-out.

+1 for threadmilling.

[cruzila]

Flakey soft copper, got it! That is the best, worst, most ambiguous description of a material. Wish me luck.

[cruzila]

Colin, would you use the DMT or full thread type? I am a bit old school, so the DMT kinda scares me.

[Colin Gilchrist]

4 hours ago, altamontmfg said:

Colin, would you use the DMT or full thread type? I am a bit old school, so the DMT kinda scares me.

I'd use DMT in almost anything, but "soft and gummy" would give me pause. I'd probably prefer to drill separately. With a normal multi-flute threadmill, you're creating nice small chips, and generally taking 2-3 passes, and possibly a spring pass.

Although, if you can get the speeds/feeds right, you'd have the advantage of "1 tool to cut the entire hole/thread/chamfer feature". And with the DMT, you can still take multi-passes. My concern would be chip flushing, and making sure the gummy/sticky chips didn't plug up the tools. But if you're only going through a 7/16" wall, I'd buy one, and see if I could get away with it.

Best thing about trying with a thread mill, if you bust one off, you can sometimes still save the part, especially if it is the first pass. And the recovery is usually much easier than breaking a tap.