Fiber breakage

Reinforcing fibers break during the transfer process causing strength decline. When glass fiber is exposed, the product surface appears white or grayish-white hazy, feels rough to the touch, and is most conspicuous on dark-colored products. This is because the surface resin failed to fully wrap the glass fiber, and the fibers are directly exposed. Abnormal glass fiber orientation macroscopically manifests as different shrinkage rates in various directions, causing the product to have unpredictable warpage deformation. Fiber-related defects are especially critical in structural parts, because fiber distribution and orientation directly affect the strength and stiffness of the product.

1. Process parameter factors: gate size too small, sharp-angle turns in the runner, transfer pressure too high, fiber length too long. 2. 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: enlarge the gate size, design the runner to avoid sharp angles and use large fillets, appropriately lower the transfer pressure, control the fiber length. 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 fiber breakage 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.