How Can I Prevent Molding Stress on Polycarb

[celnaz]

Greeting fellow professionals. I was wondering if you could share some ideas on some process techniques that can be used to effectively reduce molded in stress on PC parts. How can one effectively ameliorate molded in stress that could take away from PC's impact resistance?

Thank You All

[JayDub]

Make the gates bigger
Make the gates even bigger yet
Slow the injection speed
Anneal the parts after molding
Round off any sharp corners in the mold cavity
Raise the mold temperature

[celnaz]

Thank you for the suggestions, Jaydub

[rickbatey]

Proper mold and melt temperatures will help but you may have to profile the hold pressure portion to reduce molded in stress. Running the correct resin with additives and melt flow will make life easier. The correct size screw size utilizing an appropriate amount of shot capacity will help. A proper compression ratio helps too. Lastly don’t run resins with UV or FR additives if possible. They can bloom causing cosmetic issues and degrade with high temperatures or residence times.
Rick.