| Part Sticking in Mould | |
| Possible Cause | Suggested Remedy |
| Overpacking material in mould | a. Decrease first stage injection pressure b. Decrease boost time c. Decrease injection forward time d. Decrease packing pressure e. Increase injection transfer position (to lower injection peak pressure) |
| Improper finish on mould | Draw polish mould to proper finish |
| Insufficient draft on cavities and sprue | Polish and provide maximum allowable draft |
| Knockout system poorly designed | a. Redesign knockout system for balanced ejection forces b. Review operation of knockout system, plates not opening in proper sequence |
| Core shifting and cavity misalignment | a. Realign cavities and cores b. Add interlocks to mould halves |
| Undercuts in mould and possible surface imperfections | a. Repair and polish b. If undercut is intentional, redesign or reduce |
| Non-uniform cavity pressure in multi-cavity mould | Redesign runners and gates for balanced filling of cavities |
| Moulded parts too hot for ejection | a. Increase cooling time b. Decrease melt temperature c. Decrease mould temperature |
| Moulded parts sticking to stationary half of mould | a. Redesign sprue puller b. Apply mould release c. Increase nozzle temperature d. If parts remain on wrong side of mould, undercut other side or try differential mould temperatures |