High Precision Melt Gear Pump for Film, Sheet, Pipe, Pelletizing & EVA Blow Molding

A high-precision melt gear pump, also called an extrusion metering pump or thin-film extrusion pump, is a positive-displacement polymer metering unit widely installed between the extruder and die for plastic pelletizing, EVA blow molding, cast film, blown film, sheet and pipe extrusion lines. It separates upstream screw pulsation and delivers stable, fixed-volume molten polymer flow, which directly improves thickness uniformity, reduces scrap and supports consistent 24/7 extrusion production for thermoplastics including EVA, PE, PP, PS, TPE and filled compounds.

Conventional single-screw or twin-screw extruders naturally generate fluctuating pressure and throughput. Feed variation, screw wear, melt viscosity shift and backpressure changes will create uneven output. For thin-gauge film, clear EVA blown products, optical sheet and precision pipe, even tiny flow deviation leads to thickness drift, wavy surfaces, bubble inconsistency and wall-thickness tolerance failure. That is why extrusion lines targeting stable quality integrate a melt metering gear pump as the core pressure-stabilizing and flow-control station.

How the melt gear pump works for multi-scenario extrusion

The melt pump uses a pair of precision-machined meshing gears rotating inside a hardened alloy pump body. As gear teeth disengage on the suction side, molten plastic fills the tooth cavities. The enclosed melt is carried around the pump housing and forced out on the discharge side when gears re-mesh. Each rotation delivers a fixed volumetric displacement, so throughput stays linear with pump speed, largely independent of melt viscosity and backpressure fluctuations. Integrated heating channels and pressure sensor ports allow closed-loop control to match die requirement for film, sheet, pipe, pelletizing and EVA blow molding processes.

1. Thin-film extrusion

For cast film, stretch film and ultra-thin packaging film lines, the melt pump minimizes flow pulsation to stabilize film gauge. It eliminates streaks, thickness banding and surface defects, critical for down-gauging and high-speed thin-film production. Many BOPP, CPP and EVA film lines rely on this metering pump to tighten thickness tolerance and raise yield rate.

2. EVA blow molding

EVA is soft, shear-sensitive and prone to melt surging during blow molding. Stable melt feed delivered by the melt gear pump ensures consistent parison weight and wall thickness. It avoids thin spots, blow holes and uneven foaming for EVA foam sheets, solar encapsulation film and EVA blow-molded parts. Low-shear internal design prevents EVA thermal degradation and gel formation.

3. Plastic sheet extrusion

Solid sheet, foam sheet and decorative sheet require uniform melt distribution across the wide die. The melt pump holds steady pressure, reducing color streaks, surface ripples and density variation. It works well for transparent sheet, filled sheet and co-extruded sheet structures.

4. Pipe & profile extrusion

For PE, PP, PVC and EVA pipe, the metering gear pump stabilizes melt feeding to maintain consistent pipe outer diameter and wall thickness. It cuts over-tolerance scrap and makes pipe dimension control far easier for water pipe, drainage pipe and soft tubing lines.

5. Plastic pelletizing & compounding

In strand pelletizing, underwater pelletizing and twin-screw compounding lines, the melt pump builds stable die pressure for uniform strand output. It handles high-fill masterbatch, recycled polymer and modified compounds. Carbide bearing options are available for abrasive formulations with talc, calcium carbonate or glass fiber fillers.

Core advantages

Precise volumetric metering, throughput stability within tight tolerance

Isolate die from extruder pressure pulsation, smooth melt flow

Reduce extruder backpressure, lower screw torque and energy consumption

Protect extruder elements and extend screw service life

Lower melt temperature under equal output, reduce polymer degradation

Compatible with EVA, PE, PP, PS, TPE, recycled and filled materials

Match continuous screen changers for full filtration + metering extrusion layout

Support CE standard, customized displacement, heating and sensor configuration

Key design options

Gear material: high-speed tool steel / carbide coated for wear resistance

Sealing: high-temperature self-lubricating seals for long run with EVA and sticky resins

Heating: electric cartridge heating, uniform temperature control, no dead zone carbonization

Drive: servo motor with closed-loop speed control for accurate metering adjustment

Displacement range: small lab size to large-volume models for high-output pelletizing and film lines

Match pump displacement to your line’s rated output; oversized pumps increase melt residence time and risk EVA degradation. Install pressure transmitters at pump inlet and outlet for interlock alarm. When pairing with a continuous screen changer, place the screen changer upstream of the melt pump to filter contaminants and protect precision gear clearances. Purge thoroughly when switching colors or polymer grades to avoid cross-contamination. For EVA blow molding and foam-grade materials, choose low-shear pump profiles to suppress gel and bubble defects.

Whether you run thin film, EVA blow molding, sheet, pipe or plastic pelletizing, a high-precision melt gear metering pump upgrades your extrusion line from screw-dependent unstable output to repeatable, controllable melt delivery. It is one of the most cost-effective upgrades to cut scrap, boost running speed and stabilize finished part quality for multi-product thermoplastic extrusion workshops

Email: sale@meltpump.com

WhatsApp: +86 158 3833 1071

Any questions about our products, please feel free to contact us! We promise you high-end products and first-class service.Look forward to our cooperation!!!