Features of defect of injection molding.
It can be easily seen in the "air trap" of transparent injection parts but can also be found in opaque plastics.
This is related to thickness and is often caused by plastic shrinkage leaving the injection molding center.
2. Possible causes of problems.
(1) the mold is not fully filled.
(2) the abnormal operation of the stop valve.
(3). The plastic is not completely dry.
(4). The preform or injection rate is too fast.
(5) some special materials are used for special equipment production.
3. Remedies
(1). Increase the amount of radiation.
(2) increase injection pressure.
(3) increase the screw forward time.
(4) reduce melt temperature.
(5) reduce or increase the injection speed.(for example, plastics should be added to non-crystalloid.
Plus 45 percent speed.
(6) check whether the check valve is cracked or not functioning.
(7). The drying conditions should be improved according to the characteristics of plastics, and the plastic should be completely dry.
(8). Appropriately reduce the screw speed and increase the back pressure, or reduce the injection speed.