Stamping 6005-T5 Extrusions

[Bamadoc]

I'm stamping slots into a 6005-T5 Aluminum extrusion and the part is warping as I stamp. I'm stamping through a .750" x .535" slot through .276" material, six slots at a time and the part 'bananas' on me.
The tooling vendor says it's caused by the stress in the part during aging, and the extrusion vendor says its the clearance between the punches and the die. I'm using a standard 10" clearance, so I feel confident my tooling is good.

Any stuggestions?

 

[pecorp]

Are you making 6 slots all in one hit? If so that is a lot of stress. Try doing them one at a time and staggering them. Work from the middle out. Hope this helps

 

[Bamadoc]

pecorp
Thanks for your advice.

I've tried taking punches out, even using just one, and still have the same problem. Due to how the equipment runs, I dont have the option of starting in the middle and going towards the ends. It runs from one end to the other.
I run parts with a very similar profile and have no problem at all. However, on those parts, I'm only removing half the material thickness.