Thermoplastic Melt Pumps: Essential Equipment for Plastic Ext
A melt pump is an industrial marvel that uses a pair of precision gears to pressurize, stabilize, and precisely meter and convey molten material. It is indispensable in high-temperature and high-viscosity applications and is capable of handling the extrusion of films, pipes, and synthetic fibers.
I. Working Principle
Suction Phase: Negative pressure draws in the melt. The motor drives the drive gear to rotate → The gears disengage, increasing the volume between the teeth → A vacuum is created → The melt is “sucked” into the pump chamber
Conveyance Phase: The sealed melt is locked between the gear teeth and the pump body, and is smoothly pushed toward the outlet by the rotating gears. There is no leakage or backflow, ensuring ultra-stable conveyance.
Pressurization Phase: The gears re-engage to force the extrusion → the volume decreases → the melt is “squeezed” out. Outlet pressure can reach up to 70 MPa, and it isolates fluctuations in inlet pressure, ensuring stable output.
Key Features: Flow rate is strictly proportional to speed; adjusting speed equals adjusting flow rate, making control exceptionally easy. High outlet pressure is independent of inlet pressure, allowing for vacuum feeding and maximum adaptability.
II. Structural Components
The pump body (housing) is integrally cast and resistant to high temperatures and corrosion. It features inlet and outlet flanges (with a larger inlet and smaller outlet) that serve as both a “protective shield” and a “conduit” for the melt.
Gear Shaft (Core Component): A pair of high-precision meshing gears (drive + driven) with involute/helical tooth design. The material is primarily heat-resistant alloy steel (38CrMoAlA) that has undergone nitriding treatment, ensuring high hardness and an exceptionally long service life.
The sliding bearings are mounted at both ends of the gear shaft and rely on the melt for self-lubrication. No additional oil is required, making them wear-resistant and low-maintenance, while also preventing side leakage.
Sealing + Temperature Control System
Sealing: Combination of spiral and mechanical seals ensures zero leakage and withstands pressures exceeding 50 MPa
Heating: Electric heating rings / thermal oil dual-layer housing with temperature control accuracy of ±1°C prevents solidification and carbonization, ensuring more stable output
Drive System: Motor + reducer + coupling with variable frequency speed control delivers fast response and stable control
Why Is It So Powerful?
Precise metering with high volumetric efficiency; error <0.5%, ensuring tight control over PET sheet thickness
Energy-saving and efficiency-boosting: Reduces extruder load, cuts energy consumption by 10%–30%, and increases output by over 20%.
Rugged and durable: Suitable for temperatures ≤510°C and viscosities ≤40,000 Pa·s; handles PE, PP, PLA, and rubber with ease.
Email: sale@meltpump.com
WhatsApp: +86 158 3833 1071