How should a buyer review burn marks or short shots before approving an export injection mold for shipment?
Record the defect location, cavity, material and drying data, process sheet, short-shot or fill-balance evidence, vent-location review, correction action, retest sample and final open-item decision. Keep defect cause, correction success, sample approval, cycle, price and delivery as NEEDS_EVIDENCE until the exact project records are reviewed.
Decision checklist
- Map every defect to its cavity, sample, material and trial condition.
- Compare venting evidence with material, process and part-design variables.
- Separate mold correction from process tuning and buyer design changes.
- Require labeled retest samples and a signed open-item decision before shipment.
Do not assign a cause from one defect photo
Burn marks, gas traps, short shots and unstable weld lines can share symptoms while having different causes. The buyer should ask for cavity identity, resin lot, drying status, process settings and a defect map before deciding whether the mold, process, material or part design needs correction.
Avient's troubleshooting guidance links short parts with burn marks to gas trapping or poor venting, while other short-shot cases can involve material quantity, pressure, viscosity or flow restrictions. The correction route should therefore follow recorded evidence rather than assumption.
A corrected photograph is not closure unless the file shows what changed and how the retest was accepted.
Build a venting and correction record
Use short-shot sequences or fill-balance evidence to show where the flow front stops and where air may be trapped. Review parting-line vents, inserts, ejector-pin vents, gate location and areas that fill last, then document every tooling or process action.
Avient's mold-design guidance states that inadequate venting can cause short shots, poor appearance or weak weld lines and identifies short-shot studies as a way to locate critical venting areas. Exact vent dimensions still depend on the material and project and should remain evidence-gated.
- Labeled defect map by cavity and trial date.
- Resin, drying and process-setting record.
- Short-shot sequence and vent-location review.
- Tooling, gate, insert or parameter correction log.
- Retest comparison, accepted limit and maintenance note.
Close the issue through retest and handover
After a vent, gate, insert or process change, retain before-and-after samples with the same labeling and inspection basis. Record whether the issue is closed, accepted with a deviation or still open, and assign each remaining action to the supplier or buyer.
GEERPOWER should avoid claiming the root cause, correction result, production yield, cycle, mold approval, price or delivery until the project file proves it. If venting was part of the correction, include cleaning locations and monitoring points in the export handover package.
Common buyer questions
Does a burn mark always mean mold venting is wrong?
No. Venting may be involved, but material condition, temperature, injection speed, gate design and part geometry can also contribute. Review the recorded trial evidence before assigning cause.
Can a buyer approve shipment if the defect appeared only once?
Possibly, but the file should still identify the cavity, material, settings, sample and reason for acceptance. Repeated defects require a documented correction and retest route.
Should vent maintenance be included in mold handover?
Yes when venting was part of the trial issue or correction. Handover should identify vent locations, cleaning boundaries and areas to monitor after installation.
Sources and references used for this guide
This guide supports early project planning. Final machine selection and commercial configuration must be confirmed from the actual part, mold, material, factory utilities and production target.
