In the production process, there are always some improper operation methods, resulting in defective products. In fact, inferior products and genuine products may not be much different, such as the appearance of black spots on the surface of the entire tpe products, such TPE products will be scrapped . Observe the surface of plastic products, if the black spot is larger, it should belong to the raw material carbonization black spot; if the black spot is dark, brittle, puffy porous, can be considered a carbonization black spot; if the black spot density is particularly large, check the raw material without obvious impurities .

　　Forming impurities black spots, may be due to foreign objects mixed into the material formed black spots, must be strictly controlled production, packaging, storage, transportation, open newspaper, mixed materials to the barrel of the various aspects of cleanliness.

　　Carbonized black spots, should be strictly controlled processing temperature, because in actual production, processing temperature and the actual processing temperature is different. On the same equipment, it is different back pressure, different cycle time, different one-time injection volume, different thermocouple insertion position, it will cause the same processing temperature under the material carbonization, degradation trend is different. In other words, when the temperature is the same, the back pressure is small, the cycle time is short, the one-time injection volume is large, and the thermocouple is inserted in the upper part of the screw barrel, the melt degradation/decomposition trend is weak, and it is not easy to produce carbonization black spots. Prevent carbonization black spot at the same time to prevent the accumulation of material, to eliminate the dead ends in the screw barrel, nozzle, runner, so that the turn has a gentle transition, to eliminate the possibility of material stagnation area.

　　The black spots on the thread surface and the wall of the screw barrel, which are deposited by the degradation of additives or carbonized materials, will be discharged under the strong shearing action in the screw barrel when the black spots are removed from their original attachment surface and enter the melt. This "discharge" process is the process of products appearing black spots, impurities. Such as the transfer of material for color production, this "discharge" impurity process is inevitable, in order to try to shorten this process, the method taken is "cleaning".

　　"Cleaning" method one: the empty melt glue cleaning screw.

　　"Cleaning" method two: into the injection table melt glue, to the empty shot glue, and then into the injection table melt glue, to the empty shot glue, and so on repeatedly, practice has proved: cleaning, back pressure plays a big role, the melt and screw strong shear. The melting speed is slow, so the melting time is also long. This is a good effect, clean foreign bodies quickly.