Cold setting 300 series stainless rivits

[Charles R. Stevens]

So at our weekly gaming session my budy who is taking his turn as GM asked me about cold setting 1/4" 300 series stainless rivets in doubled over 1/8' stainless strap. Now indulge me, as Will is a manufacturing engineer working for a custom shop that dose over the road truck trim. Aperantly some one came in wanting stainless straps for his fuel tanks and figuring out how to do it fell to him. it seems he can find dies for the 25 ton press, but not wether they will cold form the rivet head. Now I set copper and aluminum and have even cold set mild steel rivets but have little experiance with stainless. Best answer I could give him is I'd bring a forge. And anvil and we could figure it out...

I think the idea of pasavating the rivets or turning me loose in his work place with a hammer may have given him pause..

any one out there who can give me the 411 on cold setting 1/4" 300 series stainless rivets I can pass on tho Will?  

[4elements]

I don't know about stainless, what about monel? I've done those on aircraft cold with a hand held rivet gun and bucking bar

[Charles R. Stevens]

I suggested a hand held riveter but not monel. I think he is trying to minimize the amount of skill required. I myself question if  25 ton is enugh press. 

 

[Jasent]

I have cold set 300 series rivets for a set of tongs. 3/8". Worked well. It will work harden some. But I had no troubles with that

[JHCC]

7 hours ago, Charles R. Stevens said:

1/8' stainless strap

Also known as 1½"?

[Charles R. Stevens]

Sorry, forgot a" ' " lol 1/8" strap, lol. 

[Frosty]

I took it as an obvious typo Charles. You almost always stick your whole foot in it. 

As long as they get with the program cold setting a stainless rivet isn't a problem. If on the other hand they play pitty pat with it it'll work harden and be a problem.

Buck it and hit it a rivet gun, electric or pneumatic is a good thing but a manual set and hammer works fine. Just HIT it.

Frosty The Lucky.

[Kozzy]

Yes, they work harden quickly so hand-setting can be a pain.  Commercially we use an orbital riveter because it results in much more even rivet heads than any hand riveting we do.  When trying to simply cold rivet in a straight press, we had problems with cracks showing up at times (300 series stainless tends to be less consistent from the mill than carbon steels...more hard and soft spots)  On those press experiments, we used a powered 75 ton press which a stroke travel of about 1 inch per second (and lower for experimentation).  Just didn't like the results or the control vs the orbital riveters.

You also need to start with a little less material forming the head than you would with mild steel when doing SS.  As the head is formed by multiple blows, the tensile strength is going to climb likely well over 100Kpsi from the work hardening so too much material to begin with doesn't improve strength and just means much more HARD material moving..or no moving at all and ugly rivets if you start with way too much (plus brittleness--the more you move, the more brittle it will be when complete).

Cold headers for stainless nails do so by making one SUPER FAST hit--that plasticizes the material differently than a series of hammer blows but would not be duplicatable in the average shop on the cheap.  VERY high pressures involved.

What we are riveting is 5/16" dia round bar.

We also hot rivet thousands and thousands of 3/16" round--this one is fully automated and uses resistance to heat the heads.  We have a 4000 amp x ~1.5 V set up where the plunger contacts the end of the rod at low pressure, hesitates while resistance brings the SS up to about 2000 degrees, then increases pressure to make the head.  Even with that we get a few cracked heads (but not many).  On my list is to see if we can induction heat instead of resistance heat the heads--problem is, the area that needs the heat is so limited that it might be hard to control (don't want to heat the clamps or other parts near the heading operation).

Obviously YMMV.