Forming parts with rubber pad question

[lakeracer69]

Here is a picture of .025 6061-T6 bent up into a rib web. It didn't bent up completely and I had to go the rest of the way in a vice. It came out alright for a first try, but I need to refine my process. It goes by the Guerin process, flowforming, rubber stamp forming etc.

The Bearhawk guys and others are using this process to bend up wing ribs with flanges, etc. For those that don't know, the metal blank is put on top of a particle board form and a thick ( 1") "rubber" sheet and steel plate are placed over it and tonnage is applied in a 20 ton press.

My question is what type of urethane or other material and durometer do I need to use. I am using a 1' thick piece of horse stall mat, but I think the durometer is too soft. Anyone know what the correct stuff to use is?

Thanks

 

[crankyklingon]

 

[crankyklingon]

 

[crankyklingon]

 

[cvairwerks]

 

[lakeracer69]