In the extrusion of plastics the thermoplastic raw material in the form of small pellets is gravity fed from a top mounted hopper into the barrel of the plastic extrusion machine. Plastic additives such as colourants and UV stabilizers (in either liquid or pellet form) can be mixed into the plastic

Plastic tubing, such as drinking straws and medical tubing, is manufactured by extruding molten polymer through a die of the desired profile shape (square, round, triangular). Hollow sections are usually extruded by placing a pin or mandrel inside of the die, and in most cases positive pressure is a