Blow molding machine screw and barrel damage causes 1, the screw in the barrel rotation, the material and the friction between the two, so that the screw and the barrel of the working surface gradually wear: the diameter of the screw gradually shrinks, the barrel of the bore diameter gradually increases. In this way, the screw and the barrel with the diameter gap, with the gradual wear of the two and a little increase.
However, because the barrel in front of the head and the resistance of the manifold has not changed, which increases the leakage flow of the extruded material forward, that is, the flow of material from the diameter gap to the direction of the feed increases. As a result, the extruder production volume decreases. This phenomenon in turn increases the residence time of the material in the barrel, causing material decomposition.
In the case of polyethylene, the decomposition of hydrogen chloride gas to strengthen the corrosion of the screw and barrel. 2, if the material has calcium carbonate and glass fiber and other fillers, can accelerate the screw and barrel wear. 3, because the material is not plasticized evenly, or a metal foreign body mixed into the material, so that the screw rotation torque force suddenly increased, this torque exceeds the strength limit of the screw, so that the screw twist off. This is an unconventional accident damage.