Uneven release agent coating

Local mold sticking or poor surface of the product. When demolding is difficult, a 'hissing' adhesion tearing sound can be heard at the moment of mold opening, the product surface shows whitening or tear marks, and obvious ejection whitening or depression occurs at the ejector rod positions. In severe mold sticking, part of the material of the product remains in the cavity and needs to be manually cleaned after shutdown, which not only prolongs the production cycle but may also damage the cavity surface. For multi-cavity molds, mold sticking of individual cavities will also cause abnormal filling of the remaining cavities.

1. Mold design factors: release agent sprayed unevenly, release agent dosage too much or too little, mold temperature affecting release agent film formation. 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. 3. Feeding factor: The volume of the feeding chamber, the feeding amount and the preheating state of the material directly determine the transfer pressure and filling effect, and are key variables unique to transfer molding.

1. Process parameter optimization and adjustment: spray the release agent uniformly, control the dosage to be appropriate, apply when the mold temperature is appropriate. 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 uneven release agent coating 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.