Not only is the use of Commercial Purging Compounds (CPCs) essential for injection molding, it has become a staple for extruders and compounders across the country. CPCs have been used less in extrusion because it can be much more difficult to clean an extruder due to lower melt pressures and the inability to move the screw to change flow velocities. However, a purge with good material affinity and detergency can offer the same benefits to extruders. Chemical purges can also be effective in cleaning hard-to-clean areas in an extruder or die. Blow molders, blown film extruders, and sheet extruders also have had success introducing purging compounds to their operations. Even compounders running low pressure twin extruders have had great success using CPCs.
The main applications for extruders include: