What factors affect the leakage and volumetric efficiency of melt pumps

1. Leakage gap of melt pump

The gear end surface leakage of the melt pump is the main part of the total leakage of the melt pump; the radial leakage caused by the gap between the top of the gear 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 leakage.

2. Conveying the viscosity of the melt

For plastic melts that follow the power-law fluid flow characteristics, 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 directly proportional to the gear speed, which in turn affects the effective viscosity and leakage flow of the fluid in the gap, and ultimately affects the volumetric efficiency of the melt pump.

4. Pressure difference between inlet and outlet

The amount of melt leakage has a large 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. Zhengzhou Bart's domestic professional melt pump manufacturing company has many years of equipment research and development and production experience, providing high-precision, high-performance melt gear pump equipment for thousands of rubber and plastic companies at home and abroad. China Zhengzhou Batte melt pump manufacturer, online consultation: info@battemachinery.com