When a process goes wrong, change one variable at a time. Start by confirming the material grade, drying condition, machine condition, actual temperatures and the location of the defect.
Possible causes: Excessive cavity pressure, insufficient clamping, mould parting-line problems or process settings can contribute.
First checks: Check clamp condition, mould alignment, fill/hold pressure, shot size and parting-line condition.
Read related guide →Possible causes: Uneven cooling, orientation, shrinkage differences or mould temperature imbalance can distort a part.
First checks: Map the defect location, compare cavity temperatures and review fill/pack/cooling balance before changing material.
Read related guide →Possible causes: Insufficient filling can result from restricted flow, low melt temperature, inadequate injection capability or venting issues.
First checks: Check actual melt temperature, gate/runner condition, injection speed, pressure limit and vents.
Read related guide →Possible causes: Local shrinkage behind thick sections may appear when packing or cooling is insufficient.
First checks: Compare wall thickness, gate freeze timing, holding pressure and cooling time.
Read related guide →Possible causes: Output surging, unstable melt temperature, die condition or feed variation can affect profile or film thickness.
First checks: Check feed consistency, melt pressure, temperature stability, screw condition and die settings.
Read related guide →Possible causes: Parison programming, die centering, stretching and mould cooling can influence distribution.
First checks: Check parison temperature/profile, die alignment, pinch-off and cooling balance.
Read related guide →Possible causes: Contamination, degraded polymer, dirty equipment or excessive residence time can create dark particles.
First checks: Inspect incoming feedstock, purge history, screens/filters, dead spots and thermal exposure.
Read related guide →Possible causes: Moisture can cause bubbles, surface defects or hydrolytic degradation in moisture-sensitive polymers.
First checks: Confirm drying temperature/time, dew point where applicable, hopper condition and material storage.
Read related guide →Write down resin grade and lot, drying condition, actual barrel/mould temperatures, cycle time, part weight, defect location, recent maintenance and any power interruption. A clean baseline makes troubleshooting much faster.
The same defect can have different causes on different machines and materials. A resin's melt flow, moisture sensitivity, filler content, colour system and thermal history can change the process window. Use this center to form a shortlist of checks, then confirm corrective action against the machine manual, mould documentation and material supplier data.