Tangless helical screw thread inserts, any negatives?

[fsincox]

My shop has asked why we are not using tangless inserts for our designs. I said, "I thought they were the ones that would be most opposed to the idea", After looking at it, I do not see and downside, anyone know of one?
Thanks,
Frank

 

[kingnero]

I'd say that depends of the application.

 

[3DDave]

I thought the tang was the part the was used to wind the insert up so it fit in the hole and to provide driving torque. It's usually removed after installation. I see one company makes them and probably requires their own special tool to drive them. It's possible they cost more - instead of winding the wire and then notching before a little twist, they have other operations to perform.

So, probably per-piece more expensive, requires special tool, but saves money on snapping off the tangs, saves worry from losing the tang in equipment and FOD.

Overall - great question. Tangless inserts look worthwhile considering.

 

[tbuelna]

fsincox-

Helical wire thread inserts, whether tanged or tangless, are the worst type of thread insert there is. While they are cheap and compact, they also have poor reliability. And worst of all they have a nasty habit of coming out whenever the mating bolt/screw is removed.

Keenserts or Rosans are a much better choice, since they are far stronger and are much more reliable.

 

[fsincox]

Thank you all for your comments, I understand they are not popular with some, The nature of my question assumes we are using them already, and is there a reason to not go to tangless, given that!
3DDave,
Thank you, this is the way it looks to me on the face of things. There are multiple manufacturers, I believe, even the "NAME" is now marketing them! It appears they were developed as a "better idea" to the traditional version the "NAME" was famous for!
Frank

 

[3DDave]

docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US4645398.pdf

 

[Tmoose]

The few times I've had problems with tangy coil inserts coming out along with the fastener it seemed to be related to blind holes that were not tapped deep enough, so when the insert was installed the deepest coil was in shallow incomplete threads, which in turn tore up the fastener threads when it was installed.

http://2.bp.blogspot.com/-XjnDUZEFBGY/US85WODq8VI/AAAAAAAABG4/kt_TGl-MdeU/s1600/sword+stone.jpg

 

[tbuelna]

fsincox-

Tangless helicoil inserts are only available in certain thread sizes, so the first thing you might wish to do is check to see if tangless helicoils are available in the size you require. Other than that, the tangless helicoil should install in the same tapped hole a tanged helicoil uses.

Ultimately, what matters most in regards to the quality of the installed helicoil in your finished product, is making sure your process for installing the helicoils is well proven, reliable and consistent. Before switching your production process from a tanged to a tangless helicoil, you should remind your manufacturing folks that even though the change seems simple, it would be a good idea to thoroughly validate the tooling and process required for the tangless helicoil.

Good luck to you.
Terry

 

[drawoh]

The few times I've had problems with tangy coil inserts coming out along with the fastener...

We have had no problems with helical thread inserts recently. Way back in the past when we did have problems, we bought thread gauges and determined that the tapped holes were out of spec. Our fabricator was using dull taps.

--
JHG

 

[tbuelna]

drawoh-

That actually brings up a good point about helical thread inserts. The accuracy of the threads in the substrate can have a significant effect on reliably the insert performs. With small diameter thread inserts (like 10-32 UNF and smaller), the total tolerance stack-up in the insert ID/OD and tapped hole threads can be significant in proportion to the thread size. This is a similar problem I have seen with small thread sizes of metal lock nuts.

 

[drawoh]

tbuelna,

The inserts we had problems with were 3/8-24UNF. We use inserts down to 2-56UNC and M2.5, and we have had no problems recently.

--
JHG

 

[Tunalover]

I've used inserts that were 1-64UNC. Just thought I'd share that. That's the smallest they make.

Tunalover