Injection molding defects should be diagnosed from the part and production evidence. A symptom such as incomplete fill, a surface streak, dimensional drift or sticking does not identify one universal cause. Start by documenting what changed, where it appears and which parts or cavities are affected.
Record the defect before selecting a remedy
Identify the part and drawing revision, resin and lot, mold and cavity, machine, production window and the exact location of the defect. Photograph affected and conforming samples under the agreed inspection conditions. Record recent material, tool, maintenance or process changes. These details help distinguish a cavity-specific condition from an issue shared across the production run.
Choose the guide that matches the observed symptom
- Incomplete filling or missing material: use the short-shot diagnosis guide.
- Silver streaks, dark marks, sinks or other appearance problems: see the surface-defect diagnosis guide.
- Dimensions vary by cavity, lot or run: compare the records described in the shrinkage-variation guide and the tolerance specification guide.
- Parts stick, drag or show ejector marks: review the part-ejection diagnosis guide.
Validate the corrective action
Use the evidence to choose a controlled investigation. Record the original condition, the change, affected cavities and sample results. Avoid applying a generic temperature, speed or pressure recipe without knowing the material, part and tool conditions. A change that improves one symptom can affect dimensions, appearance or another process result.
Release only against agreed criteria
Confirm the accepted sample, inspection method, production records and change-approval owner before releasing routine production. For broader project and supplier controls, see DAYIN’s injection-molded part inspection guide and custom injection molding service.