Diagnosing and fixing common molding defects
| Defect | Appearance | Main Cause | Primary Fix |
|---|---|---|---|
| Warpage | Part distortion | Uneven cooling, uneven shrink | Balance cooling, reduce mold temp diff |
| Sink Mark | Depression on thick wall | Insufficient pack pressure | Increase pack pressure + time |
| Flash | Thin excess plastic at parting line | High injection pressure, clamp force low | Increase clamp force, reduce inj. speed |
| Short Shot | Incomplete fill | Low injection pressure, gate too small | Increase pressure, enlarge gate or vent |
| Weld Line | Visible line where flow fronts meet | Low melt temp, flow front cooling | Increase temp, relocate gate, vent |
| Burn Mark | Black/dark spot | Air trapped, overheated | Add venting, reduce inj. speed |
| Splay | Silver streaks | Moisture in material | Pre-dry material (check spec) |