Large Form Tapping In 400 BHN

[pwilson101]

We have a job with a 1.125" - 12 thread and the parts are about 400 BHN (About an 1.5" deep, blind). The customer wants us to form tap these threads. I'm afraid I can't do that because my machine doesn't have synchronous tapping.

Any ideas or opinions? Do you think it would be ok to use a solid holder in a non-synchronous tapping machine? (I don't). What about using a tension / compression holder? I think it will compress all the way before cutting this hard material...

I'm trying to gage my chances of successfully roll forming these threads under these conditions...

Thanks

[DareBee]

Wow - I can't even imagine the monstrous HP that will take. Even in CRS that would need enormous HP.

I would like to thread mill these but that doesn't work with your customer spec.

[HuFlungDung]

400 BHN is pretty hard to form. I cannot imagine any conceivable advantage because so much stress will be induced in the part, due to the fact that the material is probably not in a very ductile state.

[DSIF]

Good luck trying to do that. The amount of horsepower required is enormous. Why should the customer dictate the method,as long as the threads are good? It's not worth wiping out your spindle for an ignorant engineer.
Dan
PS: Thread mill it.