| Warpage | |
| Possible Cause | Suggested Remedy |
| Moulded part ejected too hot | a. Decrease melt temperature b. Decrease mould temperature c. Increase cooling time d. Cool part in warm water after ejection e. Utilize shrink fixture |
| Differential shrinkage due to non-uniform filling | a. Increase injection rate b. Increase packing pressure c. Balance gates and runners d. Increase/decrease injection time e. Increase runner and gate size |
| Differential shrinkage due to non-uniform wall thickness | a. Provide increased cooling to thicker sections b. Increase cooling time c. Operate mould halves at different temperatures d. Redesign part with uniform wall sections |
| Knockout system poorly designed | Redesign knockout system for balanced ejection forces |
| Melt temperature too low | Increase melt temperature to pack out part better |
| Glass fibre orientation | Relocate gate |