Continuous screen changers use mechanical mechanism, such as a hydraulic system, to rotate new extruder screens in place of the screens that have become clogged with contaminants and cannot be used.
When using a continuous hydraulic changer for plastic extrusion, there is still some manual work needed. An operator must stand by and replace or clean the soiled extruder screens as the hydraulic system activates, and production continues.
It should be noted that contaminated extruder screens increase back pressure to the system and raise the melt temperature (due to friction), which can reduce the output of clean material.