Plastic products age and become brittle? Many reasons are at fault


1. Mold (1) The gate is too small, you should consider […]

1. Mold

(1) The gate is too small, you should consider adjusting the gate size or adding an auxiliary gate.

(2) If the runner is too small or the configuration is improper, it should be arranged to be balanced and reasonable or increase the size of the runner.

(3) Poor mold structure causes abnormal injection cycle. 

2. Equipment

(1) There are dead corners or obstacles in the barrel, which easily promote the degradation of the melt.

(2) The plasticizing capacity of the machine is too small, and the plastic is insufficiently plasticized in the barrel; the plasticizing capacity of the machine is too large, and the plastic is heated and subjected to shearing in the barrel for too long, the plastic is easy to age, and the product is changed. brittle.

(3) The ejector device is inclined or unbalanced, and the ejector cross-sectional area is small or improperly distributed.

plastic products

Three, raw materials

(1) When the raw materials are mixed with other impurities or doped with inappropriate or excessive solvents or other additives.

(2) Some plastics, such as ABS, will react with water vapor when heated under damp conditions, causing large strains on the parts.

(3) Too many times of plastic recycling, too high content of recycled materials, or too long heating time in the barrel, will cause the parts to be brittle.

(4) The quality of the plastic itself is not good, for example, the molecular weight distribution is large, and the components with uneven structure such as rigid molecular chains occupy too much; or it is contaminated by other plastics adulteration, bad additives, dust and impurities, which can also cause brittleness. the reason. 

Plastic Products Factory

Fourth, the process

(1) The temperature of the barrel and nozzle is too low, increase it. If the material is easy to degrade, the temperature of the barrel and nozzle should be increased.

(2) Reduce the screw pre-plastic back pressure and speed to make the material looser and reduce the degradation of the plastic due to shearing overheating.

(3) Mold temperature is too high, demolding is difficult; mold temperature is too low, the plastic is cooled prematurely, the weld seam is poorly fused, and it is easy to crack, especially for high-melting plastics such as polycarbonate.

(4) The cavity and core must have an appropriate draft angle. When the core is difficult to demold, increase the cavity temperature and shorten the cooling time; when the cavity is difficult to remove, reduce the cavity temperature and extend the cooling time.

(5) Use metal inserts as little as possible. Brittle plastics with a large heat and cold specific capacity such as polystyrene should not be used for insert injection molding.


Characteristics of plastic products

Five, product design

(1) The product has sharp corners, gaps or parts with large differences in thickness that are prone to stress cracking.

(2) The product design is too thin or too much hollow.  

Conclusion: Plastic products provide a lot of convenience to our lives. Although it also has many defects, we believe that the plastics industry can develop more perfect and more convenient products in the future. More about:Plastic sealing clip

Inquire Basket (0)