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Sheet Metal Kerf Cut Bends - won't Flatten

Question asked by Rick McDonald on Mar 11, 2019
Latest reply on Mar 28, 2019 by Rick McDonald

I had a problem a couple years ago and it's back to haunt me again - but in a stranger way.

We use AL-6061 heavily and to do tight bends (mostly on .060 or .090 thick material) so we need to make Kerf cuts to prevent breaking the hard material.

We can not use softer material and heat treat due to volume and speed.

I had problems with this a couple years ago on a similar part and thought it was solved but we needed to make more parts.

I had posted a couple years ago and got some suggestions that seemed to work for a part with only 1 outer flange:

Sheet Metal Relief cut for bends


How to bend sheet metal part along kerf cut without loosing ability to have flat pattern


Now I am making the parts with 2 outer flanges.

This part has 2 outer flanges that bend in one direction and 2 inner "Tab" flanges that bend in another direction.

The strange thing is I can make the part but at the final step to make a flat pattern it refuses to flatten.

If I suppress one of the outer flanges it woks fine (except for that flange that is suppressed).

I am using SW 2015 and know that some methods have change in newer versions (based on the posts listed above)

I have 1.5 deg. draft in the kerf (releif) cuts (this was one of the prior suggestions / solutions for allowing the bends, and made the cuts)

I have tried different draft amounts, changing the order of the cuts changing thickness and offset distances with no luck.

It seems that it is always only one flange that is the offending flange but if I change the order of the kerf bends it will also change the offending feature - but seems to be the outer larger bends.(tried so many combinations it may just seem that way).

Any help would be appreciated.