As a critical pressure-stabilizing metering device in polymer extrusion systems, melt gear pumps are widely used in high-end applications such as precision film production, chemical fiber spinning, and pelletizing and modification. By stabilizing melt pressure and precisely controlling flow rate, they enhance product precision and production continuity at the source, making them an indispensable core component of modern, high-efficiency extrusion lines.
1. Precision Film and Sheet Extrusion
In the production of high-end products such as CPP cast film, PVB interlayer film, and optical-grade PC sheet, the melt gear pump serves as the critical link between the extruder and the T-die. Its core functions are twofold: first, pressure stabilization and homogenization, which precisely controls pressure fluctuations at the extruder outlet (±10%–15%) to within ±1%–2% at the die inlet, significantly improving product thickness uniformity; Second, pressure boosting and delivery, which effectively overcome the 5–10 MPa pressure differential at the screen changer and the resistance in the melt piping, ensuring that the pressure at the die inlet is stably maintained within the 15–25 MPa process range. The standard process flow is: extruder → screen changer → melt pump → dynamic mixer → die.
2. Filament Spinning for Synthetic Fibers and Nonwoven Fabrics
Spinning processes for polyester, nylon, and polypropylene filaments, as well as melt-blown nonwoven fabrics, demand extremely high stability in melt flow rate and pressure. Commonly referred to in the industry as melt metering pumps or spinning pumps, these units feature precise displacement ranging from 0.5 to 30 cc/rev, enabling constant melt flow delivery. The equipment offers strong controllability of operating parameters: operating temperature of 280–320°C and outlet pressure of 8–20 MPa, ensuring a deviation in single-hole filament output of less than 1% to meet high-quality spinning requirements.
3. Pelletizing and Recycled Modification
In two-stage extrusion pelletizing production lines, the melt gear pump serves as a core component, converting the fluctuating melt output from the upstream extruder into a stable, high-pressure flow suitable for systems such as underwater pelletizing and strand pelletizing. For highly filled materials containing calcium carbonate or glass fiber at levels exceeding 50%, as well as high-viscosity recycled and modified materials, the pump employs carbide bearings and a specialized gear tooth profile. This design offers excellent wear and corrosion resistance, enabling long-term stable operation under severe conditions.
