Extrusion is understood as low pressure extrusion for the production of slightly dispersed dust-free granulates.
If cylindrical granulates are achieved, a process using the Gear Pelletizer comes into use. Typically granulates of 1 to 10 mm diameter are produced. In the Gear Pelletizer the extrusion takes place by a pair of counter rotating hollow toothed rollers.
For shingled, highly porous granulates with good dispersal properties the Bextruder is used. With the Bextruder the material is compressed with an extrusion rotor with a perforating die.
The rounding off of pellets is known as spheronisation. This process is often used after an extrusion process in which soft granulate is produced with the Bexroller.