Analysis of the reasons for product cracking in injection mold processing!

Author: MULAN - Plastic Molding Manufacturer

Different injection molds have different requirements. Today, the mold injection molding processing factory will analyze the reasons why the injection mold causes product cracking during processing: 1. Injection molding: (1) Excessive pressure, excessive speed, excessive filling, Excessive injection and pressure holding time will cause excessive internal stress and cracking. (2) Adjust the mold opening speed and pressure to prevent rapid forced drawing from demoulding and cracking. (3) Properly increase the mold temperature to make the parts easy to demould, and properly reduce the material temperature to prevent decomposition.

(4) Prevent cracking due to low mechanical strength due to fusion marks and plastic degradation. (5) Correctly use the release agent, and frequently remove the aerosol and other substances attached to the surface of the mold. (6) The residual stress of the part can be eliminated by annealing heat treatment immediately after forming to reduce the occurrence of cracks.

2. Mold: (1) The ejection should be balanced, such as the number and cross-sectional area of ​​the ejector pins should be sufficient, the demoulding slope should be sufficient, and the surface of the cavity should be smooth enough to prevent cracking due to the concentration of ejection residual stress caused by external forces. (2) The structure of the workpiece should not be too thin, and the transition part should adopt a circular arc transition as much as possible to avoid stress concentration caused by sharp corners and chamfers. (3) Metal inserts should be used as little as possible to prevent differential shrinkage between inserts and parts from increasing internal stress.

(4) Appropriate demoulding air inlet pipes should be provided for deep bottom parts to prevent the formation of vacuum negative pressure. (5) The gate is sufficient to demould the gate material before solidification, so it is easy to demould. (6) The connection between the sprue bushing and the nozzle should prevent the cold and hard material from dragging and causing the workpiece to stick to the fixed die.

3. Materials: (1) The content of recycled materials is too high, resulting in low strength of parts. (2) Excessive humidity can cause some plastics to react with water vapor, reducing strength and causing jet cracking. (3) The material itself is not suitable for the processing environment or is of poor quality, which will cause cracking if it is contaminated.