Meaning
Extrusion and compounding lines utilize positive displacement gear pumps to deliver a constant and uniform flow of molten polymer to the die. Operating downstream of the extruder screw, the melt pump isolates the die from pressure fluctuations and screw surges. This equipment ensures precise dimensional control of the extruded product.
Pressure Stabilization
Pressure variations in the extruder barrel caused by inconsistent feeding or screw design degrade the quality of extruded sheets and pipes. By absorbing these fluctuations, the melt pump maintains a steady head pressure at the die inlet. The gear mechanism dispenses a precise volume of polymer per revolution regardless of upstream pressure changes.
Consistent pressure ensures uniform wall thickness and reduces material waste.
Energy Efficiency
High discharge pressures generated solely by an extruder screw can overheat the polymer and consume significant mechanical energy. When a melt pump is integrated, the extruder screw is relieved of the task of building high pressure, allowing it to operate at lower temperatures and speeds. The pump generates the required pressure much more efficiently than the screw.
This separation of melting and pumping functions reduces thermal stress on the polymer.
Output Control
Manufacturing thin films or high-precision profiles requires a very tight tolerance on the mass flow rate of the resin. The output rate of the melt pump is directly proportional to its rotational speed, which is adjusted dynamically through a closed-loop control system. This system adjusts the extruder screw speed to maintain a stable inlet pressure at the pump.
Precise regulation of the throughput prevents under-extrusion and over-extrusion defects.
