When there are black spots in the process of plastic granulation, we have to think about what is the problem? Is there a problem in the granulation machine, or is there a problem in the raw materials, or is it because of some other factors? When we encounter such problems, the first thing we have to do is to analyze the reasons.
There are many possible black spots, which can be found in the packing, in the raw materials, and not in the raw materials, but after carbonization in the screw: there will be more dust outside; In the actual production of plastic products, the feed port is usually isolated before shutdown to eliminate the plastic melt in the extruder and die, turn off the temperature in each area, and then turn off the power supply.
Large and medium sized extruders that can plasticize molecular weight plastics can be cleaned with high molecular weight plastics or their recycled materials plus white mineral oil. Because the hardness of high molecular weight plastics is better, and when the temperature is higher, the cleaning object will be softened, and then become easy to fall down, which is conducive to the carbide being carried out by the plastic melt. During the cleaning process, the rotation speed of extruder was repeatedly switched between low speed and high speed. If the load of the motor has a margin, the extruder can be stopped and restarted repeatedly during the operation, so as to further improve the actual cleaning effect. When the carbides (black spots) in the melt decrease obviously, the usual plastic should be replaced and cleaned until it is clean, and the temperature should be adjusted gradually to the appropriate temperature, then normal production can be achieved.
The harm of carbonization to plastic products is not light, so we should try our best to avoid the loss of plastic products. Try to minimize the loss. As for the way, we need to use two aspects to collect. Don't worry about the actual effect. It's only a matter of time.