Embrittlement

The toughness of the product decreases and it breaks easily. 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, excessive curing agent dosage, aged and deteriorated material, poor fiber impregnation. 2. Preheating factor: The preheating temperature and time of the material (especially thermosetting molding compounds) directly affect its flowability and curing behavior; improper preheating will lead to poor filling or uneven curing, and it is a key control point unique to compression molding. 3. Molding pressure factor: In compression molding, pressure is not only used to overcome flow resistance, but also directly affects the compactness of the product and the degree of fiber impregnation; insufficient pressure is an important cause of product looseness and insufficient strength.

1. Process parameter optimization and adjustment: control the curing time, reduce the curing agent dosage, check the shelf life of the material, improve the resin's impregnation of the fibers. 2. Systematic troubleshooting method: Troubleshooting of compression molding problems follows the order of 'material -> temperature -> pressure -> mold'. First check the preheating and flowability of the material, then verify the mold temperature distribution and curing time, then adjust the molding pressure and mold closing speed, and finally check the mold venting and demolding conditions. 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.