Causes of screw wear
1, each plastic, there is an ideal plastic processing temperature range, should control the barrel processing temperature, so close to the temperature range. Granular plastic from the hopper into the barrel, the first will reach the feeding section, in the feeding section is bound to appear dry friction, when the plastic heat shortage, melting uneven, it is easy to cause the barrel wall and screw surface wear increases. Similarly, in the compression section and the homogenization section, if the plastic state of the molten state is uneven, will cause wear and tear faster.
2, the speed should be adjusted properly. As part of the plastic plus a reinforcing agent, such as glass fiber, mineral or other filler. These materials on the metal material friction is often much larger than the molten plastic. In the injection of these plastics, if the high speed into, then increase the shear force on the plastic at the same time, will also make the corresponding to produce more shredded fiber, the shredded fiber contains sharp ends, so wear Force greatly increased. Inorganic minerals in the metal surface high-speed taxi, the scrapping effect is not small. So the speed should not be transferred too high.
3, the screw rotation in the barrel, the material and the friction between the two, so that the screw and the barrel of the working surface gradually wear: screw diameter gradually reduced, the barrel of the hole diameter gradually increased. In this way, the screw and the barrel with the diameter of the gap, with the gradual wear and tear of the two slightly increased. However, since the resistance of the head and the manifold in front of the barrel does not change, this increases the leakage flow when the extruded material is advanced, i.e., the flow of material from the diameter gap to the feed direction. Resulting in the decline in the production of plastic machinery. This phenomenon also makes the material in the barrel to increase the residence time, resulting in material decomposition. If it is polyvinyl chloride, the decomposition of hydrogen chloride gas to strengthen the corrosion of the screw and barrel.
4, if the material such as calcium carbonate and glass fiber filler, can speed up the screw and barrel wear.
5, because the material is not plasticized evenly, or a metal foreign body mixed with the material, so that the screw rotation torque force suddenly increased, this torque exceeds the screw strength limit, the screw twist. This is an unconventional accident damage.