Product embrittlement

Insufficient toughness and easy to break. Embrittled products break under normal use loads, with flat and smooth fracture surfaces without plastic deformation traces, showing typical brittle fracture characteristics. In impact tests, the notched impact strength of embrittled products may drop to below 30% of the normal value. The danger of embrittlement is that the appearance is often normal and is only exposed when stressed, so for safety-related products (such as helmets, safety seats, electrical enclosures), embrittlement is an unacceptable major quality accident.

1. Material factors: over-curing, fibers broken during the transfer process causing reduced reinforcement effect, material containing volatiles producing micropores, excessive curing agent. 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: control the curing time, optimize the runner to reduce fiber breakage, remove volatiles, reduce the curing agent dosage. 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.

The essence of embrittlement is that the material's toughness reserve declines to the point of being unable to meet use requirements. The control key is the 'three temperatures'——processing temperature (avoid excessive degradation), drying temperature (avoid too low leaving residual moisture and too high causing thermal oxidation), mold temperature (affecting crystallization and residual stress), as well as controlling the heating history and residence time of the material.