Extrusion blow molding is a process for directly manufacturing hollow plastic bottles/containers by using the standard extruder screw and barrel assembly to plasticise the polymer. This molted mass (called parison) is a tube-like piece of plastic with a hole in one end in which compressed air can pass through. After dropping from extruder, this hollow tube is captured by closing it into a water-cooled mold as well as knife cut the parison at the top. When the molds are closed and moved sideways

Produce gear by extrusion method | Mechanical And Electrical Engineering