How are dimpling dies made?

Aluminum · #1 01-23-2021, 09:56 AM

Would appreciate a mini-treatise by the engineers on here.

Toobuilder · #2 01-23-2021, 10:11 AM

With a lathe.

terrye · #3 01-23-2021, 12:43 PM

This would be a question for Mike Lauritson at Cleaveland Aircraft Tool.

Aluminum · #4 01-23-2021, 02:11 PM

Quote:

Originally Posted by Toobuilder

With a lathe.

Almost certainly for roughing, but after heat treatment I imagine the fit would be off? What kind of grinding/polishing procedure produces the little shiny beauties at that sort of precision for a few bucks a pop? Am I overthinking it?

G-force · #5 01-23-2021, 04:41 PM

I can't say for certainty, but typically dies are machined from a hardenable steel while in their soft state on a lathe to slightly oversize. Then hardened and tempered to whatever spec is called for. Then finally, precision ground to final size and desired surface finish.

lr172 · #6 01-24-2021, 11:55 AM

I wouldn't necessarily assume they are hardened. Their primary job is bending light gauge, aluminum and a non-hardened alloy steel would work well for that purpose without hardening. Pretty easy to confirm. Just run a file over the stem. If it skates, it's hardened. If it bites in, it is annealed. I damaged the point / end on one and was able to use a file to dress it up, if I recall correctly.

hardened tool steel is not required for bending light gauge aluminum. At least not in non-production situations.

1001001 · #7 01-24-2021, 12:39 PM

They could probably be made in mass quantities by forging them. Wouldn't take much to form them by upsetting a hot piece of rod in a series of forming dies. The upsetting/forging process would make them quite tough. Post heat treat if necessary, then electropolish. The ones I have don't seem to have lathe-like tool marks on the non-polished side.

scsmith · #8 01-24-2021, 05:21 PM

I'm pretty sure mine are made from 17-4 PH age-hardening stainless steel.
It is hardened to H900 by simply aging in an oven at 900F for 3 hrs, then air cooled. It is Rockwell C43 at that point, and machines better in that state than in the solution-treated condition. So it would just be machined and ground in that hardened state. You can buy bar stock already treated to H900 to machine what ever you want out of it.

Aluminum · #9 01-24-2021, 10:57 PM

Quote:

Originally Posted by scsmith

I'm pretty sure mine are made from 17-4 PH age-hardening stainless steel.

Huh, interesting! Which brand are they? I know for sure that at least two out of the brands I own are nowhere near stainless. 17-4 wouldn't rust like these did. OK, now we need someone with access to an XRF gun and a bunch of dimple dies.

DaleB · #10 01-25-2021, 07:10 AM

Quote:

Originally Posted by lr172

I wouldn't necessarily assume they are hardened. Their primary job is bending light gauge, aluminum and a non-hardened alloy steel would work well for that purpose without hardening. Pretty easy to confirm. Just run a file over the stem. If it skates, it's hardened. If it bites in, it is annealed. I damaged the point / end on one and was able to use a file to dress it up, if I recall correctly.

hardened tool steel is not required for bending light gauge aluminum. At least not in non-production situations.

I have one that I modified with a file to fit into a tight spot. It's most definitely not hardened steel, the file has no trouble with it at all.