Excessive product shrinkage

The product dimensions are too small. Shrinkage problems manifest as the product's dimensions continuously shrinking after demolding, with a fast initial shrinkage rate (70%-80% of the total shrinkage completed in the first 24 hours), then slowly tending to stabilize. When shrinkage is uneven, the product shows dimensional differences or deformation; when the shrinkage amount is too large, the product exceeds the lower tolerance. The shrinkage of compression and transfer molded products is significantly affected by curing conditions and post-curing processes, which is different from the thermoplastic shrinkage mechanism of '2079851475616104452.

1. Process parameter factors: large curing shrinkage rate, insufficient transfer pressure, high mold temperature, insufficient feeding amount. 2. Runner and gate design factor: In transfer molding, the material needs to enter the cavity through runners and gates; the runner length, cross-sectional shape and gate size directly affect pressure loss, fiber breakage and filling balance, and unreasonable design is the root of many quality problems.

1. Process parameter optimization and adjustment: use low-shrinkage material, increase the transfer pressure, lower the mold temperature, increase the feeding amount. 2. Systematic troubleshooting method: Troubleshooting of transfer molding problems follows the order of 'runner -> feeding -> parameters -> mold'. First check whether the runners and gates are blocked or worn, then verify the feeding amount and material preheating, then adjust the transfer pressure and speed, and finally check the mold venting and temperature uniformity. 3. Preventive management: Establish standardized process parameter cards and quality control limits for each set of mold/product, and regularly conduct process capability index (CPK) evaluations. For recurring problems, use fishbone diagrams or 5Why analysis to trace the root cause, and solidify the countermeasures as PFMEA control points.

This problem is a typical manifestation of excessive product shrinkage in transfer molding; the core of the solution lies in the rational design of the runner and gate system, the effective transmission of transfer pressure, and the uniform control of mold temperature. It is recommended to start troubleshooting from the runner system and transfer parameters.