What's new
What's new

Aluminum spring back

gr8life

Cast Iron
Joined
Dec 9, 2007
Location
Las Vegas Nevada
I have looked all thru the Machinery's Handbook and can not find the answer. I need to bend some 6061 to an inside radius of 4.3 inches and need to know how small I should make the die it will be pressed to.
Any help?
thanks
ed
 
Large radius spring-back numbers are elusive and can change from one material batch to another. Cross grain -vs- with the grain will also have an affect.

I experiment by going about 20% under and bending narrow strips of the actual material. Measure the results and adjust as required (wrap paper or sheet metal around the radius bar for minor adjustments). The best formulas are empirical and will only get you in the ballpark with very large radius bends.
 
Thanks for the answer I was expecting but did not want to hear. Using your formula would I assume the thinner the material the less spring back?
thanks 4 your quick reply.
ed
 
As far as I know, with all else equal (which it never really is), spring back is the essentially the same for different thicknesses when the bend radius is an equivalent percentage of thickness. Temper will affect spring back (but not force required to bend).

*My 20% number is a hip shot, my experimentation usually begins with an existing conveniently sized radius bar or bit of scrap.
 
Yikes, this is indeed a tall order with alu; apart from anything else, the degree of temper drifts with time.

If this is a recurrent job, you'll probably need to either make the die adjustable if possible, or shop around (make test coupons and a simple portable tester for springback so you can qualify material at source)

The only other things you could do are 'iron' the bend area, which takes strong tooling and lots of tonnage, or use a tangential/ stretch tool of some sort (If it's a 2D bend)

Possibly if it's a 3D bend you could grip the blank on all sides and apply multidirectional pre-tension prior to (and during) forming, but it would be tricky to avoid Luders lines.
 








 
Back
Top