In the injection molding problems, plastic products brittle is a headache and can not ignore the problem, the product is a large part of the brittle due to internal stress caused by the toughness of the material itself is not good, then the product prone to product hair Brittle problem. In fact, the reasons for crisp products are also cliché, summed up that also several aspects. Many customers, when the product appears brittle situation, the first doubt is the material there is a problem, of course, undeniable, the material problems, it may lead to brittle products, but the injection of brittle products, There are many, we have specific problems specific analysis.
First, raw materials
1) barrel has dead ends or obstacles, easy to promote melt degradation.
2) The plasticizing capacity of the machine is too small, the plasticization of the plastic in the barrel is not sufficient; 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
3) The ejection device is tilted or unbalanced, the top dry cross-sectional area is small or the distribution is improper.
4) Heating in the base barrel for too long.
Second, the mold side
1) gate is too small, should consider adjusting the gate size or additional auxiliary gate.
2) Shunt is too small or improperly arranged, should be arranged to balance the reasonable or increase the size of the diversion channel.
3) mold structure caused by poor injection cycle abnormal.
Third, the process aspects
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 screw pre-cast back pressure and speed, so that the material is slightly loose, and reduce the plastic due to shear overheating caused by degradation.
3) Mold temperature is too high, mold release difficult; mold temperature is too low, plastic premature cooling, weld fusion bad, easy to crack, especially high melting point plastics such as polycarbonate, etc. is even more so.
4) cavity core to have the appropriate stripping slope. When the core is difficult to mold, to improve the cavity temperature, shorten the cooling time; cavity difficult to off, to reduce the cavity temperature, extend the cooling time.
5) as little as possible with metal inserts, such as polystyrene such brittle hot and cold than the capacity of plastic, but can not join the insert injection.
Fourth, raw materials
1) when the raw material is mixed with other impurities or doped with an improper or excessive amount of solvent or other additives.
2) some plastic such as ABS, etc., in the damp conditions will be heated with water vapor catalytic cracking reaction, so that the workpiece has a large strain.
3) the number of plastic recycling or recycling material is too high, or in the barrel heating time is too long, will lead to cracked parts.
4) plastic itself, poor quality, such as the molecular weight distribution, containing rigid molecular chain and other non-uniform structure of the component is too large; or by other plastic doping pollution, adverse additive pollution, dust pollution, The
Fifth, product design aspects
1) products with prone to stress cracking of the sharp corners, gaps or thickness of the great difference between the parts.
