How to Properly Clean the Barrel of a Plastic Granulator

Cleaning the barrel of a plastic granulator typically involves material replacement cleaning. Before cleaning, it's essential to understand the technical data regarding the thermal stability, molding temperature range, and compatibility between various plastics of the material currently in the barrel and the material to be replaced. During cleaning, it's crucial to follow the correct operating procedures to save time and material. There are two methods for material replacement cleaning: direct replacement and indirect replacement.

Direct Replacement Method: If the material to be replaced and the material currently in the barrel share a common melting temperature, the direct replacement method can be used. The operating procedures for direct replacement are as follows. If the molding temperature of the material to be changed is higher than the temperature of the material remaining in the barrel, the barrel and nozzle temperatures should first be raised to the minimum processing temperature of the material to be changed. Then, the material to be changed should be added, the die head opened, and extrusion performed directly until the remaining material in the barrel is completely cleaned. Afterward, the temperature should be adjusted for normal production. If the molding temperature of the material to be changed is lower than the temperature of the material remaining in the barrel, the barrel temperature should first be raised to ensure the remaining material is in its optimal flow state. Then, the heating power to the barrel and nozzle should be cut off, and the material to be changed should be used for cleaning while cooling. Once the temperature drops to the processing temperature of the material to be changed, production can resume.

Indirect Material Change Method. If the material to be changed and the material remaining in the barrel do not share a common melting temperature, the indirect material change method can be used. The operating procedure for indirect material change is as follows. If the molding temperature to be changed is high, and the remaining material in the barrel is heat-sensitive, such as polyvinyl chloride (PVC) or polyoxymethylene (POM), a two-step cleaning method should be used to prevent plastic decomposition. First, use a heat-stable plastic such as polystyrene or low-density polyethylene (LDPE), or recycled plastic from these types, as a transition cleaning material. Then, replace the transition cleaning material with the material to be changed. Disassemble the screw. Since the screw of a plastic granulator is relatively easy to disassemble, in many cases, the material change method described above is not necessary. This method saves raw materials.