Views: 0 Author: Site Editor Publish Time: 2025-03-03 Origin: Site
01 Introduction A melt pump is a mechanical device used to transport high-temperature molten materials. It improves product quality and production efficiency by precisely controlling the melt flow and pressure, while also reducing energy consumption and production costs. As a result, melt pumps are widely used in industries such as plastics, rubber, chemicals, and food processing. This article will primarily introduce the working principle, types, and functions of melt pumps.
02 Working Principle The working principle of a melt pump is mainly based on the mechanical structure of a gear pump. It uses a pair of intermeshing gears that rotate within the pump chamber, transporting molten material from the intake to the discharge. The entire process can be divided into three stages.
(1) Intake Stage
Through the meshing rotation of the gears, a local vacuum is created, drawing material into the pump chamber.
(2) Transfer Stage
As the gears continue to rotate, the material is gradually pushed forward by the contours of the gears, moving toward the discharge.
(3) Discharge Stage
When the gears rotate near the discharge, the space between the gears gradually decreases, compressing the material as it moves into the downstream pipe.
03 Types of Melt Pumps
(1) Straight Tooth Melt Pump
This type of melt pump has a simple structure, is easy to manufacture, and is convenient for maintenance. It is typically used for low-to-medium viscosity melts. However, due to the small pump chamber, the flow uniformity is relatively poor, and it is prone to clogging when used with high-viscosity materials. Additionally, it tends to generate more noise and vibration.
(2) Helical Tooth Melt Pump
Compared to straight tooth gear pumps, helical gear pumps offer better flow uniformity and are suitable for high-viscosity fluids. Their larger pump chamber and smoother flow paths make them less prone to clogging. Furthermore, the helical design ensures smoother operation, better gear meshing, and reduces the noise often found with straight gear pumps.
(3) Screw Tooth Melt Pump
Screw tooth melt pumps are ideal for high-viscosity, high-solid content fluid media. The screw tooth design creates smoother flow channels within the pump chamber, reducing fluid friction and resistance, thus improving flow uniformity. These pumps feature a monolithic design, offering higher strength and the ability to withstand higher operating pressures. Additionally, they have excellent high-temperature resistance and lower shear forces, making them suitable for transporting polymer materials and high-viscosity fluids.
04 Functions of Melt Pumps
(1) Pressure Stabilization Protection
Melt pumps provide stable pressure and flow, which is crucial for ensuring product quality and the continuity of the production process. They maintain output consistency under varying production conditions such as changes in temperature and pressure. Furthermore, melt pumps act as a buffer between extruders and downstream equipment, reducing wear and pressure shocks on downstream components.
(2) Precise Metering, Improving Efficiency
In certain applications, such as co-extrusion or multi-layer co-extruded film production, melt pumps can precisely meter the melt of different components to ensure uniformity and consistency in product structure. They also reduce downtime caused by pressure fluctuations, thus improving overall production efficiency.
(3) Improved Mixing Effect, Suitable for High-Viscosity Melts
Melt pumps can also serve as static mixers. Through their internal structure design, they enhance the mixing effect of different components while maintaining the transport of high-viscosity melts.
05 Key Indicators of Melt Pumps
(1) Flow Rate
The flow rate of a melt pump refers to the amount of molten material required to be pumped, typically ranging from 20 grams per minute to 500 grams per minute. The specific flow rate is selected based on actual production requirements.
(2) Temperature
The working temperature of a melt pump generally does not exceed 350°C, and the cleaning temperature can reach up to 450°C.
(3) Pressure
There are two pressures to consider: the pressure before the pump (P1) and the pressure after the pump (P2). The difference between these two pressures is called the pressure differential. In actual production, the values of P1 and P2 need to be monitored to adjust the pump speed. If P1 is too high, the speed can be increased to improve the situation. If increasing the speed does not help, there may be a blockage in the downstream pipe (such as the fine filter or melt pump), and corresponding components need to be cleaned.
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