What are the factors related to the leakage of the melt pump?
During the use of the melt pump, due to improper operation, operating conditions and other issues, the melt will leak. Zhengzhou Batte's melt pump manufacturer analyzes the reasons for the leakage of the melt pump from the following four aspects.
1. Leakage gap
Gear end leakage is the main part of the total leakage. The radial leakage caused by the gap between the gear top and the melt pump body and the bearing gap accounts for a minor part of the total leakage. The leakage caused by the gap between the tooth surfaces only accounts for a small part of the total leakage and can be ignored.
In order to compensate for the manufacturing tolerances, elastic deformation, thermal deformation and melt-lubricated bearings of various parts, the leakage caused by the gaps is inevitable. Only by optimizing the design of the gaps as much as possible to improve the manufacturing and processing accuracy of the melt pump To limit the amount of leakage.
2. Melt viscosity
For plastic melts that follow the flow characteristics of power law fluids, the leakage flow rate is inversely proportional to the "effective" viscosity of the fluid in the gap. Obviously, plastic melts with low viscosity are more likely to leak than those with higher viscosity, so relatively speaking, the delivery viscosity is higher. For high plastic melt, the volumetric efficiency of the melt pump is higher.
3. Operating process conditions
The "effective" viscosity of the fluid in the gap is a function of the melt temperature and the shear rate of the fluid in the gap. On the one hand, the effective viscosity of the melt changes. If the temperature rises, the melt viscosity decreases and the leakage increases. On the other hand, the fluid shear rate in the gap is proportional to the gear speed, which in turn affects the effective viscosity and leakage flow rate of the fluid in the gap, and has an impact on the volumetric efficiency of the melt pump.
4. Pressure difference between inlet and outlet
The amount of leakage has a great relationship with the pressure difference between the inlet and outlet of the melt pump. Under this pressure gradient, the plastic melt leaks from the high pressure area to the low pressure area through the channels formed by the gaps. For the melt that follows the flow characteristics of the power law fluid: the pressure difference is a comprehensive parameter of the melt temperature, pump speed, inlet flow and other factors.
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