Melt pumps are positive displacement conveyance devices. Their core operating principle relies on the rotation of a pair of meshing gears to forcibly convey high-temperature, high-viscosity polymer melts. The entire process is a continuous cycle and consists of the following three steps:
Suction: When the pair of gears inside the pump chamber rotates in opposite directions driven by the motor, the teeth in the feed zone gradually disengage. This causes the working volume between the gear teeth to expand, creating a local negative pressure or vacuum that draws the melt from the reactor or extruder into the pump body, filling the gear teeth.
Conveyance: As the gears continue to rotate, the melt enclosed between the tooth slots and the pump casing is forced along the inner wall of the casing from the inlet side to the outlet side. During this process, the melt is confined within a sealed space, achieving “forced transfer.”
Discharge: In the discharge zone, the teeth of the two gears re-engage, causing the enclosed volume to decrease. This exerts a powerful squeezing force on the melt, forcing it out of the tooth pockets and into the discharge pipe, thereby generating high pressure.
Key Characteristics: Direct Proportional Relationship: Since the volume of the gear teeth is fixed, the pump’s flow rate is strictly proportional to its rotational speed. This allows for extremely high metering accuracy through variable frequency speed control.
Pressure Stabilization and Decoupling: The melt pump acts as a “barrier” between the extruder and the die, isolating upstream pressure fluctuations to ensure stable output pressure and enhance product quality.
Tianjin Ruicheng Pump Industry Co., Ltd. specializes in melt gear pumps. The melt pumps it manufactures are typically constructed from high-temperature tool steel and wear-resistant alloys to withstand the harsh conditions of high temperatures and pressures. They are widely used in production lines for chemical fibers, pelletizing, film manufacturing, and petroleum extrusion.
