Do you know the Cause of Cracking of Plastic Products?

Do you know the Cause of Cracking of Plastic Products?

As a Plastic Tape Plastic Core Wholesaler, I would like to share with you the reasons for the cracking of plastic products. Cracking, including filamentary cracks, microcracks, whitening, cracking on the surface of the part, or trauma crisis caused by the sticky mold of the part or the sticky mold of the flow channel, according to the cracking time, the mold is cracked and applied. The main reasons are as follows:
                                                                                  
                                                                                                                                         Film Coil Core Tube

Processing

1. Excessive processing pressure, too fast speed, more filling, longer injection and holding time will cause excessive internal stress and cracking.

2. Adjust the mold opening speed and pressure to prevent the demoulding and cracking caused by the fast and strong drawing parts.

3. Properly increase the mold temperature to make the part easy to demold, and appropriately lower the material temperature to prevent decomposition.

4. Prevent cracking due to weld marks and degradation of plastic due to degradation of plastics.

5. Appropriate use of release agent, pay attention to often eliminate aerosol and other substances attached to the mold surface.

6. Residual stress of the workpiece can be reduced by the annealing heat treatment immediately after forming to eliminate the internal stress and reduce the generation of cracks.

In terms of mold

1. Ejection should be balanced. For example, the number of ejectors and the cross-sectional area should be sufficient. The demolding slope must be sufficient. The cavity surface must be smooth enough to prevent cracking due to the residual stress concentration caused by external forces.

2. The structure of the workpiece must not be too thin. The transition part should use arc transition as much as possible to avoid stress concentration caused by sharp corners and chamfers.

3. Minimize the use of metal inserts to prevent the internal stress from increasing due to the difference in shrinkage between the insert and the part.

4. Appropriate demolding air inlet channels should be set for deep bottom parts to prevent the formation of vacuum negative pressure.

5. The main stream is enough for the ambassador's gate material to release from the mold when it solidifies in the future, which is easy to release.

6. The joining of the main flow bush and the nozzle should prevent the drag of the cold hard material and make the product stick to the fixed mold.

In terms of materials

1. The content of recycled material is too high, which causes the strength of the part to be too low.

2. Excessive humidity causes some plastics to react with water vapor to reduce strength and cause ejection cracking.

3. The material itself is not suitable for the environment being processed or the quality is poor, and pollution will cause cracking.

Machine side

The plasticizing capacity of the injection molding machine should be appropriate. If it is too small, it will not be fully mixed and brittle. If it is too large, it will degrade.

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