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Punching 316 S.S. .........questions

smalltime

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Jan 10, 2010
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Kansas City
We have a high volume project that requires punching thru 316 s.s.

The hole sizes are around .250" and thicknesses are .050 and the second is around .030.

Does this grade work harden more than other "milder" grades, such as 304?

Should we count on either carbide, or CPM, or will D2 be sufficient?

I'd like to run around 3% clearance if possible, to reduce tumbling time.

Any insight would be helpful.

Thanks in advance.
 
Factory where I worked years back ran a lot of 304 and 316 SS. Punches and dies were bought from Wilson Tool and were just hardened tool steel. For the thickness you mentioned we ran .006" to .010" clearance. Punching was done on CNC turret punches and a Strippitt single station punch. I have no idea on work hardening.
 
Factory where I worked years back ran a lot of 304 and 316 SS. Punches and dies were bought from Wilson Tool and were just hardened tool steel. For the thickness you mentioned we ran .006" to .010" clearance. Punching was done on CNC turret punches and a Strippitt single station punch. I have no idea on work hardening.

There's no way I'm running 20% clearance. That's too big of a burr for this app.

Was there a difference in the two alloys you mentioned, or were they comparable in terms of wear?
 
CPM 10V or M4 are best in my experience. I also think you're going to find the 3% clearance is to tight for stainless and you're going to have massive flank wear from rubbing. Is this a application that can fit in a turret punch? Then it's just two hits. One punch and then coining back the burr with a forming tool.
 
IME comes a point were dropping clearance won't really reduce the burr in a worthwhile way just bump tool loading and increase forces - wear rates.
 
CPM 10V or M4 are best in my experience. I also think you're going to find the 3% clearance is to tight for stainless and you're going to have massive flank wear from rubbing. Is this a application that can fit in a turret punch? Then it's just two hits. One punch and then coining back the burr with a forming tool.

I will discuss the 3% with the boss. We're also worried about the breakout with this app.

I can coin back the burr in a prog die. And I had left provisions for that in my proposal, but it's hard to do that with the blankout punch.:D

This is exactly the info I wanted regarding materials. I can do CPM, but we have to account for the added costs.

FYI:
we currently run 304 stainless in a prog die that has virtually no clearance, but the matl is .005, half hard.

at around 100,000 hits we just switch out the punches. But they are much smaller, at .012 x .120.
 
I had a great reply written last night. Looked great on the screen right up until the power went out.

316 is harder than 304, but not much. No less than 5%/side. HSS punches will work the best. HSS oar CPM-10V for die.

Don't know what your "high volume" is. We had parts where we got an order for 200K
JR
 
There's no way I'm running 20% clearance. That's too big of a burr for this app.

Was there a difference in the two alloys you mentioned, or were they comparable in terms of wear?

We ran 18ga up to 7ga in CRS, HRS, galvanized, SS, and bronze all on the same tooling, so I couldn't say about wear. We would run whatever job was next, just change the dies to get the proper clearance for the mat'l thickness.
 
I had a great reply written last night. Looked great on the screen right up until the power went out.

316 is harder than 304, but not much. No less than 5%/side. HSS punches will work the best. HSS oar CPM-10V for die.

Don't know what your "high volume" is. We had parts where we got an order for 200K
JR

I'm pretty comfortable working with CPM, so we'll probably go with that.
I did get some more info today, looks like well north of the 200k you mentioned.

Also, we are probably looking at a tumbler operation.
 
We run a lot of 302SS and 304SS, and some 316SS, from .001" - .125" thick.

We use CPM10V for punches/dies whether we purchase from Wilson or cut them ourselves.

Punches from Wilson are specified with their "Optima" coating.

We run 17.5% clearance.

15% is the recommended minimum in SS.

Do not go below 10% punching or blanking unless you really like working on dies a lot.

edit:

Check out page 42 of Jerry Arnold's "Die Makers Handbook"
 








 
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