What Does a Melt Pump Do in Recycled Plastic Extrusion? On the same production line, switching to a different batch of raw material can change the extrusion output. Die pressure may fluctuate, sheet thickness may become uneven, and strand diameter may vary during pelletizing. These problems are often related to differences between material batches, uneven feeding, changes in melt temperature, and increased filter resistance.
When output fluctuates, operators usually adjust the screw speed first. However, the screw handles plasticizing, mixing, pressure generation, and material conveying at the same time, so changing its speed may not fully stabilize the output. A melt pump for recycled plastic extrusion conveys material through rotating gears. With sufficient inlet feeding and a suitable processing temperature, pump speed can be adjusted to control flow and reduce the influence of upstream fluctuations on the melt delivered to the die.
After a melt pump is installed, it takes over part of the pressure-building duty from the screw. Operators can then adjust extruder settings according to actual plasticizing and degassing conditions. For recycled PET sheet extrusion and recycled PE and PP pelletizing lines, a more stable melt flow into the die helps control product thickness, dimensions, and strand diameter.
Recycled materials often contain considerable impurities. When selecting a melt pump, a matching screen changer can be specified according to the material type, impurity content, throughput, and required filtration fineness. Filtration reduces the amount of hard contaminants entering the pump, lowering the risk of gear and bearing wear. During operation, operators should monitor filter resistance and pump inlet pressure, replace screens promptly, and maintain a steady melt supply.
Tianjin Ruicheng Pump Industry Co., Ltd. manufactures melt pumps for recycled plastic extrusion. Pump displacement, drive, and sealing configurations can be selected according to the material, throughput, temperature, and inlet and outlet pressures, helping the equipment meet the operating requirements of the production line.
