How to deal with black spots in large extruder screw

Most of the extruder processing materials are mainly PE, PVC, TPU, etc. The thermal history of these materials is not long. If they stay in the screw for a long time, black spots will occur. In some large extruders, the barrel is connected to the die. The flow channel in the middle is relatively long, and some have storage tanks. There are many corners and dead corners, which are easy to hide glue, and are more likely to produce black spots than ordinary extruders.

Extruder screw barrel for PVC plastic machine


As we all know, there will be black spots when shutting down, so how to clean up the black spots in the screw after shutting down? Pulling the screw can completely remove the impurities on the screw, but it takes very little time to pull the screw, and the impurities in the barrel and die have not been effectively treated. In addition, often dialing the screw is also challenging the precision of the machine.

For the sake of the machine, it is better to use less screw. For the black spot problem in the market, there is a special extruder black spot cleaning material, which can effectively clean out the original black spots in the machine table. After the black spot is resolved, we suggest to find the source of the black spot and focus on prevention, which will require much less time and materials, while ensuring normal production.

For example, most of the black spots are caused by the shutdown, we recommend using the shutdown maintenance material, and adding it to the Conical twin screw barrel during the shutdown can prevent the residual material from decomposing and carbonizing, thereby preventing the generation of black spots.