Melt Pump for Film Extrusion

The melt pump for film extrusion is a crucial piece of equipment widely used in the plastics industry, particularly in the field of film extrusion molding. Below is a detailed introduction to the melt pump for film extrusion:

I. Working Principle

The melt pump for film extrusion is a positive displacement conveying device. Its working principle mainly relies on the change in working volume caused by the meshing of the driving and driven gears to convey the melt. When the gears rotate in the specified direction, the melt enters the tooth grooves of the two gears in the feeding area. As the gears rotate, the melt is brought into the conveying area. When the gears mesh again, the melt in the tooth grooves is squeezed out of the discharging area and pressed into the outlet pipeline. This process is continuous; as long as the pump shaft rotates, the gears continuously press and convey the melt towards the outlet side.

II. Main Structure

The melt pump for film extrusion mainly consists of a pump casing, a driving gear, a driven gear, sliding bearings, front and rear end plates (or side covers), gland seals (or shaft seals), etc. These components work together to ensure stable melt conveyance and pressurization.

III. Functional Characteristics

Pressurization and Pressure Stabilization: The melt pump for film extrusion can pressurize and stabilize the high-temperature plastic melt from the extruder, feeding it stably into the extruder die, thereby eliminating extruder screw pulsation and improving product quality.

Improved Die Pressure Stability: Through continuous and stable melt conveyance, it significantly enhances the stability of die pressure, contributing to the production of high-quality, uniform film products.

Reduced Energy Consumption: Under constant pressure, the melt pump features a low shear stress design, which helps reduce the energy consumption and operating temperature of the extruder, improving output rates.

Pressure Isolation: The gears in the pump act as a rotating barrier, effectively isolating the impact of pressure fluctuations and flow rate fluctuations in the feeding area on the discharging area.

IV. Application Fields

The melt pump for film extrusion is widely used in various fields such as sheet materials, blown film and cast film production, spray coating, textiles (including fibers and non-woven fabrics), EVA processing, mixing, pelletizing, and biodegradable materials. Especially in the field of film extrusion molding, the role of the melt pump is indispensable.

V. Technical Parameters

The technical parameters of the melt pump for film extrusion vary by model and application scenario, but typically include the following aspects:

Model: Melt metering pump models range from 0.5CC to 12000CC, and can also be customized according to user needs.

Operating Temperature: Generally not exceeding 350°C, with a cleaning temperature not exceeding 450°C.

Outlet Pressure: Typically not exceeding 350bar.

Viscosity: Generally not exceeding 40,000Pa·s.

In addition, the material of key components such as the pump body, end covers, and gear shafts also directly affects the performance and service life of the melt pump. Common materials include alloy steel, nitriding tool steel, etc.

VI. Operation and Maintenance

When using the melt pump for film extrusion, it is necessary to monitor the melt pump to a certain extent, including indicators such as outlet pressure, suction pressure, inlet and outlet pressure difference, motor current, gear shaft sealing, and pump temperature, to ensure its normal operation. At the same time, regular maintenance is also crucial for ensuring the long-term stable operation of the melt pump.

In summary, the melt pump for film extrusion is an important piece of equipment in the field of film extrusion molding, featuring multiple functional characteristics such as pressurization, pressure stabilization, improved die pressure stability, and reduced energy consumption. During operation and maintenance, attention should be paid to its technical parameters and performance indicators to ensure its normal operation and long-term stability.

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