Causes of screw wear and ways to minimize it

1, each plastic, there is an ideal plasticization processing temperature range, should control the barrel processing temperature, so that it is close to this temperature range. Granular plastic from the hopper into the barrel, will first arrive at the charging section, in the charging section will inevitably appear dry friction, when these plastics are not enough heat, melting unevenly, 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 melting state is disorderly and uneven, it will also cause increased wear and tear.

2. The rotating speed should be adjusted properly. As part of the plastic with reinforcing agents, such as glass fiber, minerals or other fillers. These substances on the metal material friction is often much larger than the molten plastic. In the injection molding of these plastics, if the high speed into, will increase the shear force on the plastic at the same time, will also make the reinforcement accordingly produce more torn fibers, torn fibers contain sharp ends, so that the abrasion force is greatly increased. Inorganic minerals in the metal surface at high speed skating, its scraping effect is not small. So the speed should not be adjusted too high.

3, to check the debris in the plastic. Generally speaking, the original purchase of fresh plastic and no debris, but after transportation, weighing, drying, color mixing, especially the addition of recycled back to the material, there may be mixed with debris. As small as metal shavings, as big as a heating coil nut paper clip, and even strings of warehouse keys, mixed into the barrel have occurred, which is self-evident damage to the screw (barrel of course, will also be damaged at the same time), so it is necessary to install the magnet frame, strict feeding management and monitoring.

4, the moisture contained in the plastic, the screw surface wear has a certain impact. If the plastic in the injection before not all the water excluded, the residual moisture into the screw compression section, it will be formed before the melt mixed in the molten plastic with high temperature pressure of the "steam particles", with the injection process screw advancement, from the homogenization section up to the head of the screw, these "steam particles These "vapor particles", which unload and expand during the injection process, are like fine impurity hard particles that produce friction damage to the wall.

In addition, for some kinds of plastics, under high temperature and high pressure, moisture may become a catalyst to promote the cracking of plastics, resulting in harmful impurities that can erode the metal surface. Therefore, plastic injection molding before the drying work, not only on the quality of the parts have a direct relationship, but also affects the working life of the screw.