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[Edna Morgan]

Hi all, working on a sheet metal design and trying to form a C-channel in 2mm stainless (304). The depth is 50mm, and I’m wondering if I’m asking for trouble with bending—springback, cracking, or just general forming headaches. Anyone dealt with something similar? Would tweaking the bend reliefs or flange lengths help keep things in shape, or is there a better way to approach this?

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[Mattias]

Bending will be a bit of a challenge on those dimensions – you are asking for a bit of trouble with the springback and cracking when cold working a stainless steel. If you could get rolled channel directly, that would be easiest.

But if you are prepared for a bit of trial and error with the sheet metal, I expect that you can get it to work. You can definitely play with the bend reliefs to reduce stress concentrations and therefore reduce the risk of cracking. You could also use some preheating to help, but of course you need to be careful that you do not raise the temperature enough to change the grain structure (so 700°C or lower is ok).

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[Rafael Angulo]

What type of bending setup do you have? I’m assuming you have a hydraulic press brake V-bending? Are you planning on bottoming to the die, or having an air gap? The bottoming into a V-shaped die would be better to counteract the springback from the 304, but you’ll have to overbend slightly to allow for some springback. Remember also that stainless needs more power to overcome its work hardening behavior, so you need to be sure that you have more pressure applied to your press.

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