What are the benefits of installing a screen changer downstream of a melt pump?

The screen changer is designed to filter foreign matter such as carbides and unmelted polymer from the molten polymer to prevent product quality degradation. In addition, the screen changer can also filter out large pieces of solids that damage the melt pump. Usually, the screen changer is only installed upstream of the melt pump to achieve the above two purposes. However, we recommend installing a screen changer downstream of the gurnay melt pump to ensure product quality while saving more than 30% energy.

When the screen changer is installed upstream of the melt pump, the screen changer is a hindrance to pressure, so the extruder itself must perform some pressurization; however, the extruder has a lower pressurization capacity than the melt pump. When it pressurizes the screen changer, the extruder will generate additional heat. In order to achieve the necessary outlet pressure, the extruder must increase the speed; this will increase the polymer temperature, reduce the polymer viscosity, and destroy the volumetric efficiency of the equipment; at the same time, it will also lead to a decrease in energy efficiency.

By adjusting the screen changer to the downstream of the melt pump, the melt pump can fully exert its boosting function; at the same time, the outlet pressure of the extruder can be reduced. While ensuring the energy saving of the extruder device, the temperature of the polymer can also be reduced to make it stable. However, the volumetric efficiency of the traditional melt pump is low, and it cannot effectively boost the downstream die head and screen changer by relying on it alone. Therefore, the screen changer is installed downstream of the melt pump.