Although the extruder＇s performance data has increased almost tenfold over the years, the rheological characteristics of the plastic to be processed have not changed very much. Formulations currently in use have been made much leaner in terms of additives, and have a relatively narrow processing window. To exploit the full scope for performance increases, the extruder design is subject to extremely high demands, such as are found in only a few other plastics processing areas, The loads on the screws and gearing are typical examples of a range of other extruder components.