annealing to eliminate warpage??

[mjh368]

i have two parts the first is for simplicictys sake a CPVC bar and the second is a teflon 3/4 in rod. The bar has notches machines and the rod has a hole drilled through its length. The bar and the rod come out of the machine op with around a 1/32 bow. Some co-workers have suggested annealing to eliminate the warpage. What i know about annealing is that is it used to relieve stress to improve mechanical properties. I have speculaed that annealing could make warpage worse, as material shrinks and relaxes more???? Is this correct

 

[plastx]

That's true. It depends on what is causing the part to warp. Bars and rods usually have relatively low stress as compared to injection molded parts. The CPVC would be fairly straight forward to test annealing. Place in an oven within 10F of the glass transition temperature. Time is dependant on the thickness of the part. For best results the parts should be cooled slowly as well. The Teflon, if PTFE, has a much higher glass transition temperature, over 550F.

Mike