Stress Relief for 6061-T6

[JohnHen]

We are maching very close tolerances with 6061-T6 and seem to be experiencing a problem with the aluminum moving after maching. I was wondering if there was a way to stress relieve 6061-T6 before machining. We are removing a large portion of metal on subject projects.

Thanks for any help.
JohnHen

 

[israelkk]

The best recommendation in the ASM metals handbook 8th edition is to let the parts rest for 2 weeks after the heavy machining and then just finish the accurate dimensions with small feed and sharp tools. It is unwise to heat treat aluminum alloys outside the metal manufacturing facilities.

 

[rerig]

The recommended procedure is to "Hog-out" the piece to a rough dimension, Heat Treat, then finish the final dimension machining. Most large Aircraft OEMs do this on their Detail Drawings.

 

[Hydroformer]

Agreed, let it rest, then finish cut it.

If you heat treat it, it will no longer be in T6 condition.

regards,

Hydroformer

 

[cncguy]

Close tolerance machining on aluminum is a tricky thing. First, was the material cut from sheet or bar? Was it cut with the grain? Is the material drawn or rolled stock?

I've stress relieved 6061 by putting it in an oven after roughing at 375 for 6hrs. Sometimes machining processes are enough to relax the material. I don't believe you can take all the stress out of aluminum. Heat and cold play a major factor.

We are experiencing some problems lately with the finished product twisting after electroless nickel and baking to asure adhesion. This is done at 250 to 300 for 1.5 hrs.

Hope some info will help,

cncboss1