TROUBLESHOOTING GUIDE INDEX FOR INJECTION MOLDING BMC Topic Philosophy Of Troubleshooting Molding Problems Injection Processing Problems Crazing / Cracking Contamination Dieseling Drag marks Dull Appearance Flash ( Excessive ) Flow Lines Injection Too Slow Knit Lines Laking Nonfills Or Short Shots Pin Cracking Pre Cure Screw Pickup Is Erratic Screw Pickup Is Too Slow Scumming Shrinkage Sink Marks Sprue Sticking Sticking In Mold Trapped Gas ( Burn Marks ) Warpage Wood Screwing Troubleshooting Chart and Comment Sheet Date Printed, Date Revised Page Injection 1 Injection 2 Injection 2 Injection 3 Injection 3 Injection 3 Injection 4 Injection 4 Injection 4 Injection 5 Injection 5 Injection 5 Injection 6 Injection 6 Injection 6 Injection 7 Injection 7 Injection 7 Injection 8 Injection 8 Injection 9 Injection 9 Injection 10 Injection 10 Injection 11 Inserts Injection 11