Cracking of plastic products during injection molding of molds is a common defect.
Time: September 9, 2024
Cracking of plastic products during injection molding of molds is a common defect that may affect the appearance and performance of products. The appearance of cracks may be caused by various factors, including residual stress, external stress, and external environment. The following will provide a detailed introduction to the three major causes and solutions for cracking in plastic mold products.
1、 Cracking caused by residual stress is one of the main reasons for plastic product cracking, usually caused by excessive filling, demolding, and metal inlay. The methods to solve this situation can start from the following aspects: 1 Consider using multi-point distribution point gates, side gates, and handle shaped gates to reduce cracking near the sprue.
2. Properly increase the resin temperature, reduce the melt viscosity, improve fluidity, and reduce stress.
3. Reasonably adjust the mold temperature to avoid stress increase caused by excessively low temperature.
4. Control injection and holding time to avoid excessive stress.
5. For amorphous resins, special attention should be paid to the generation of stress.
2、 Cracks caused by external stress are mainly caused by unreasonable design, especially at sharp corners where special attention should be paid to stress concentration. Reasonable design of product structure to avoid stress concentration can effectively reduce the occurrence of cracking.
3、 Chemical cracking caused by external environment, water degradation caused by moisture absorption, and excessive use of recycled materials can all lead to physical deterioration, resulting in cracking. When embedding metal parts in injection molding, attention should be paid to the difference in thermal expansion coefficients between metal and resin, which may lead to stress generation and long-term cracking.
To prevent cracking, it is necessary to comprehensively consider factors such as material selection, process parameter adjustment, and product design to ensure the quality and performance of plastic mold products. By using scientific methods and summarizing experience, the occurrence of cracking defects can be effectively reduced, and the quality and reliability of products can be improved.