What factors are related to the leakage of melt pump?

During the use of melt pump, due to improper operation and operating conditions, melt leakage will be caused. Zhengzhou Batte melt pump manufacturer analyzes the reasons for the leakage of melt pump from the following four aspects.

1. Leakage gap

The leakage of gear end face is the main part of the total leakage. The radial leakage caused by the clearance between the top of the gear and the melt pump body and the bearing clearance accounts for a minor part of the total leakage. The leakage caused by the clearance between tooth surfaces only accounts for a small part of the total leakage, which can be ignored.

In order to compensate the manufacturing tolerance, elastic deformation, thermal deformation and melt lubricated bearing of various parts, the leakage formed by setting various gaps is inevitable. Only by optimizing the design of gaps as much as possible and improving the manufacturing and processing accuracy of melt pump can the leakage be limited.

2. Melt viscosity

For the plastic melt following the flow characteristics of power-law fluid, the leakage flow is inversely proportional to the "effective" viscosity of the fluid in the gap. It is obvious that the plastic melt with low viscosity is easier to leak than that with high viscosity. Therefore, the volumetric efficiency of the melt pump is higher when transporting the plastic melt with high viscosity.

3. Operating process conditions

The "effective" viscosity of the fluid in the gap is a function of melt temperature and fluid shear rate in the gap. On the one hand, the effective viscosity of melt changes. If the temperature increases, the melt viscosity decreases and the leakage increases. On the other hand, the fluid shear rate in the gap is directly proportional to the gear speed, which affects the changes of fluid effective viscosity and leakage flow in the gap, and affects the volumetric efficiency of the melt pump.

4. Inlet and outlet differential pressure

The amount of leakage is closely related to the differential pressure between the inlet and outlet of the melt pump. Under the action of this pressure gradient, the plastic melt leaks from the high-pressure area to the low-pressure area through the channel formed by each gap. For the melt following the flow characteristics of power-law fluid, the differential pressure is a comprehensive parameter of melt temperature, pump speed, inlet flow and other factors. info@battemachinery.com