Tap For 6Al4V?

[darkzero]

Can I get away with using a common tap from the hardware store (Vermont) for titanium? Size is 5/16" & will be done by hand. If not will I have to buy something better? How about this OSG 3 Flute? Suggestions?

I never threaded Ti using a tap, will it be a PITA like drilling with HSS bits?

Thanks

 

[precisionworks]

Can I get away with using a common tap from the hardware store

Only if you love misery

Lots of factors in play when threading Ti ... the material is moderately hard (28-38 HRc) and ordinary taps are meant for soft materials, usually under 20 HRc.

Then add the "elastic memory" of Ti, meaning that the material closes tightly around the cutting tap, generating friction and heat, resulting in increased wear of the cutting edges.

On top of that, Ti easily work hardens.

All the major tap makers offer Ti specific taps. Those incorporate additional clearance to overcome the extreme elastic memory.

Also, there is more back taper of the threads (from the front to the back of the thread section), full radial clearance in the threads (across the tap lands), and additional relief in the chamfer area.


If the hole is all the way through the part, a spiral point tap works well, like the Balax Series BX160 A286 Spiral Point. For a blind hole, the Balax Thredfloer does a nice job.


Size the tap drill for the lowest percentage thread that's acceptable, usually about 65%, which give additional clearance within the hole.


A phone call to a few of the manufacturers will get some specific recommendations.

 

[darkzero]

Thanks

"elastic memory" of Ti

Ti easily work hardens.

Would I be better off using a cut tap over forming?

 

[darkzero]

Thanks to a PM I think I will just go with what was recommended to me but still curious.

Balax Thredfloer vs Threadshaver

I never used a forming tap (I think) before. How do the two differ, a tap does not always "cut" threads?

 

[CKOD]

Thanks to a PM I think I will just go with what was recommended to me but still curious.

Balax Thredfloer vs Threadshaver

I never used a forming tap (I think) before. How do the two differ, a tap does not always "cut" threads?

My experience is with threadforming in aluminum not titanium, so some stuff could be different...
With thread forming taps you drill a slightly larger hole then normal, and the tap screws its way into the hole, deforming the metal, so that correct thread profile is left. This also cold-works the metal, making stronger threads on metals which cold-forging strengthens them. On work hardening metals, this could be a benefit if you can get it tapped, because now your threads are hardened some. But its obviously bad if it hardens too much while youre in the middle of tapping and just refuses to tap any further.

Imagine drilling a hole in a piece of plastic, and just wrenching a bolt in, and how it mashes the plastic to have the threads, rather then cutting, same thing here.

 

[cmacclel]

In my opinion the only tap I would use for 6al-4v is the Emuge taps that are specifically designed for Titanium. I tried thread forming taps as Jhanko swears by them but had no luck. Then I spent $30+ on the Emuge 4-40 from MSC and it tapped Ti almost as easy as aluminum. I have since bought 4 of them. I also bought the OSG tap for titanium and it's junk compared to the Emuge.

http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=346&PMITEM=02770782&PMCTLG=54http://www1.mscdirect.com/CGI/NNSRIT?PARTPG=NNLMFI&PMPXNO=1707007


Mac

 

[precisionworks]

An Emuge rep just wrote "Tips for Tapping Titanium" in Canadian Industrial Machinery. Short article with good info.

http://www.cimindustry.com/article/tooling/tips-for-tapping-titanium

 

[PhotonFanatic]

It's been a while since I've bought taps for Ti, but as I recall the tap I purchased was specifically made for Ti. The feature I found most intriguing for those taps was that the tap actually cut the Ti on it's way out of the hole! Yes, to overcome, as Barry mentioned, the elastic nature of the material. The tap worked great, btw.