A mold aspect (1) gate is too small, should consider adjusting the gate size or increase the auxiliary gate.
(2) If the flow channel is too small or improperly configured, it should be arranged as reasonable as possible or increase the size of the flow channel.
(3) Poor mold structure caused abnormal injection cycle.
2. Equipment (1) There are dead spots or obstacles in the barrel, which can easily promote the degradation of the melt.
(2) The plasticizing capacity of the machine is too small, the plastic is not fully plasticized in the barrel; the plasticizing capacity of the machine is too large, the plastic is heated and sheared in the barrel for too long, the plastic is easy to age, and the product is changed brittle.
(3) The ejection device is inclined or unbalanced, and the top dry cross-sectional area is small or improperly distributed.
Three Raw Materials (1) When raw materials are mixed with other impurities or doped with inappropriate or excessive solvents or other additives.
(2) Some plastics such as ABS, etc., which are heated under moisture conditions, will undergo catalytic cracking reactions with water vapor, causing large strains on the parts.
(3) Too many plastics are regenerated or the content of recycled materials is too high, or the heating time in the barrel is too long, it will promote the parts to be embrittled.
(4) The quality of the plastic itself is poor, for example, the molecular weight distribution is large, the content of components containing an inhomogeneous structure such as a rigid molecular chain is too large, or the contamination by other plastics, the contamination of undesirable additives, the contamination of dust and impurities are also caused by brittleness. the reason.
Four aspects of the process (1) barrel, nozzle temperature is too low, increase it. If the material is easily degraded, the temperature of the barrel and nozzle should be increased.
(2) Reduce the back pressure and speed of screw pre-molding to make the material slightly loose, and reduce the degradation of the plastic caused by shearing overheating.
(3) mold temperature is too high, mold release is difficult; mold temperature is too low, plastic premature cooling, poor fusion fusion joints, easy to crack, especially in high melting point plastics such as polycarbonate and so on.
(4) The cavity core must have an appropriate draft angle. When the core is difficult to release from the mold, the cavity temperature must be increased and the cooling time must be shortened. When the cavity is difficult to remove, the temperature of the cavity must be reduced and the cooling time must be extended.
(5) Minimize the use of metal inserts, such as polystyrene, which is a brittle plastic with a large cold-to-hot ratio, and it cannot be inserted into injection molding.
Five-product design aspects (1) Products with sharp corners, notches, or areas with widely varying thicknesses that are prone to stress cracking.
(2) The product design is too thin or too hollow.
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