When selecting a melt pump for an extrusion line, connection dimensions and the extruder model alone are not enough. The material, throughput, temperature, pressure, and actual operating conditions must all be considered.
Materials such as PET, PP, PE, PC, PA, and TPU vary considerably in viscosity and flow behavior at different processing temperatures. Material viscosity also affects the torque and rotational speed required to operate the melt pump. Before selecting a pump, confirm the material type, approximate processing temperature, and viscosity range.
A melt pump has a specified theoretical displacement per revolution. The required displacement should be determined based on hourly throughput, material density, and normal operating speed. If the pump is too small, it may need to run at a higher speed to achieve the required output. If it is too large, its speed during normal production may be too low, making further adjustment more difficult.
If the melt pump is installed between the extruder and the die, consider both the pressure available at the pump inlet and the pressure required by the downstream filter, piping, and die. Inlet pressure, outlet pressure, and the actual differential pressure directly affect pump selection and drive configuration.
Operating temperature, seal type, heating method, installation space, and the selection of the motor and gearbox must also be determined according to site conditions. If the line experiences die pressure fluctuations or unstable output, or if product thickness and dimensional consistency are important, a comprehensive assessment is needed before selecting the pump.
When selecting a melt pump for an extruder, provide at least the material name, processing temperature, throughput, inlet pressure, outlet pressure, and connection dimensions of the existing equipment. More complete data makes it easier to determine the appropriate pump displacement and operating range, while reducing compatibility issues during installation and commissioning.
