In the pelletizing process of the plastic pellet machine, it is a common problem that black spots appear on the pellets. Is the issue of black holes arising in the granulation process of the plastic pellet machine? Is it a problem of the plastic pellet machine or the raw material problem, or do other factors cause it?

The reason why the particles made by the plastic pellet machine have black spots

The problem of black spots during the pelletizing process of the plastic pellet machine is a common failure phenomenon, especially for coloured and light-coloured plastic pellets. Often in the final production process, the colour of the plastic pellets is found to be no problem, but After a while, there will be black spots, and at this time, entangled in the issue of why there are black spots, has caused many friends to have a headache. Of course, encountering such a situation is a headache.

There are mainly the following six types of black spots in plastic particles

1. The filler may have black spots;
2. There may be black spots in the raw materials;
3. There may be black spots in the raw material filler;
4. There may also be black spots after carbonization in the screw;
5. There will be black spots if there is too much dust outside;
6. The uneven dispersion of toner can also cause black spots and so on.

The solution to the black spots on the particles produced by the plastic pellet machine:

1. In the actual production of the plastic pellet machine, the feed inlet is generally isolated before the shutdown; the plastic melt in the plastic pellet machine and the head is removed; the temperature control system in each zone is turned off, and then the power is turned off.
2. Since the plastic melt has strong adhesion to the metal, it is impossible to eliminate it every time the machine is shut down completely. In the end, there will always be a thin layer of plastic melt that will firmly adhere to the plastic pellet machine. After the engine is stopped, the residual plastic in the barrel of the plastic pellet machine is naturally cooled and cooled, and it will go through a healing process after the next start. In this way, if it stays in a high-temperature state for a long time, the plastic will be obvious. The thermal deterioration is gradually turning yellow, zooming into carbides.

According to the conventional shutdown method, effective sealing measures are not taken at both ends of the die opening and the feed opening of the plastic pellet machine head, which causes air to enter the machine to produce oxidation, which promotes aggravation of the thermal degradation of the residual plastic in the machine, and provides benefits for carbonization. Condition. Because the equipment is a metal structure, the thermal expansion rate is quite different from that of plastic, and the adhesion of carbonized plastic to metal is reduced, and it is easy to fall off from the inner wall of the barrel, the inner wall of the head and the screw of the plastic pellet machine, and mix into the plastic melt. After a long time of shutdown, heating and restarting, many large and small black spots are prone to appear on the plastic particles, which cannot meet the quality requirements of the plastic particles. These black spots are the carbides after the thermal deterioration of the residual plastic in the machine.

Solution: Take the method of continuously extruding the residual plastic and eliminate the plastic melt with black spots to clean the machine. The washing time is up to 3-5 hours. Therefore, if you need to reproduce after a long period of shutdown, use clean pp recycled materials to add a small amount of water to clean the barrel, which can effectively remove the residual material and foreign matter on the screw and barrel of the waste plastic pellet machine.