What are the functions of melt pumps for TPU extrusion?
When processing TPU films, pipes or profiles, some production lines suffer from uneven discharge, fluctuating thickness and inconsistent dimensions. Operators usually adjust temperature and screw speed first. If instability persists after adjustments, it is necessary to check material feeding, filter resistance and pressure upstream of the die head.
Different TPU grades exhibit different flow behaviours during processing. Discharge fluctuations may be caused by temperature variations, uneven screw feeding or rising resistance as filters get used over time. The screw is responsible for plasticizing and mixing materials as well as pushing melt towards the die head. Adjusting the rotating speed alone cannot reliably stabilize all these processes.
An extrusion melt pump is normally installed between the extruder and die head. It conveys melt continuously via rotating gears. With sufficient feed upstream of the pump and proper temperature, output can be controlled by adjusting pump speed, mitigating the impact of upstream fluctuations on die feeding. Once the pump takes over part of the pressure build-up task, screw settings can be optimized for better plasticization and degassing.
For model selection, extruder size or flange interface alone are not sufficient. Factors including TPU grade, hourly output, processing temperature, inlet & outlet pressure and viscosity range must be evaluated to properly match displacement, drive and temperature control. Attention should also be paid to insufficient feed before the pump due to clogged filter screens.
Tianjin Ruicheng Pump Industry can customize matched melt pumps and screen changers for TPU extrusion lines based on actual working conditions. Providing material and operation parameters helps determine the optimal configuration for your production line.
