The screw in the machine barrel rotation, material and the friction between the two, so that the screw and the cylinder of the working surface gradually wear: the screw diameter is gradually reduced, the inner hole diameter of the barrel is gradually increasing. In this way, the diameter of the screw and the cylinder with the gap, with the gradual wear and tear of the two.
But because the resistance of the barrel in front of the head and the flow distribution plate is not changed. This increases the was extruded material progress when the leakage flow, namely the material from the spacing between the diameter to the direction of feed flow rate increased. The result is that the production of the extruder is reduced.
This phenomenon also causes the material to stay in the machine barrel to increase, resulting in material decomposition. If it is polyethylene, the decomposition of hydrogen chloride gas to strengthen the screw and barrel of the corrosion.