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          How to improve the use of screw barrel technology?
          Author:administrator ?? Posted on:2018-04-25 12:03:55 ?? Text:【Big】【Medium】【Small】Browse (101)
          Summary:The injection screw works for a long time under high temperature......

          The injection screw works for a long time under high temperature, high pressure, high mechanical torque and high friction environment. The first few factors are required for the process conditions, and the wear caused by friction is unavoidable. In general, the screws are surface-nitrided to increase the surface hardness, ie, to increase the wear resistance. However, if the cause of wear is ignored and the wear is not reduced as much as possible, the working life of the screw will be greatly reduced.

          The following describes the causes of screw wear and how to reduce wear:

          1. Each type of plastic has an ideal plasticizing processing temperature range. It is necessary to control the processing temperature of the cylinder to make it close to this temperature range. When the granular plastic enters the cylinder from the hopper, it will reach the feeding section first, and dry friction will occur in the feeding section. When these plastics are heated insufficiently and unevenly molten, it is easy to cause the wear of the inner wall of the cylinder and the surface of the screw to increase. In the same way, in the compression section and the homogenization section, if the melt state of the plastic is unbalanced, the wear increases.

          2, the speed should be adjusted properly. Due to the addition of reinforcing agents to some plastics, such as glass fibers, minerals or other fillers. The friction of these materials on metal materials is often much greater than that of molten plastics. In the injection molding of these plastics, if high rotational speeds are used, the shearing force of the plastic will be increased, and the strength will be correspondingly increased to produce more shredded fibers. The shredded fibers have sharp ends and wear. The force is greatly increased. When inorganic minerals slide at high speed on the metal surface, their scraping effect is not small. So the speed should not be adjusted too high.

          3, to remove plastic debris. In general, the original purchased fresh plastic does not contain any impurities, but after transporting, weighing, drying, mixing, and especially adding recycled raw materials, it is possible to mix impurities. Small metal swarf, large heat-resistant ring nut clips, or even a chain of warehouse keys, have mixed into the barrel once happened. This damage to the screw is self-evident (the barrel of course will also be damaged at the same time ) Therefore, magnet racks must be installed, strict management and monitoring of feeding.

          4. The moisture contained in the plastic has a certain influence on the wear of the screw surface. If the plastic does not completely remove moisture before injection, the residual moisture enters the screw compression section, forming a steam-blown steam particle that is melted in the molten plastic before. As the screw progresses during the injection, the homogenization section Up to the head of the screw, these vapour particles decompress and expand during the course of the injection process. They are like tiny particles of fine particles that produce friction and damage to the walls. In addition, for certain types of plastics, at high temperatures and pressures, moisture can become a catalyst for the cracking of plastics, producing harmful impurities that can attack the metal surface. Therefore, the drying of the plastic before injection molding not only has a direct bearing on the quality of the part, but also affects the working life of the screw.

          Zhoushan Weiye Plastic Machinery Manufacturing Co., Ltd.

          ©2019 Zhoushan Weiye Plastic Machinery Manufacturing Co., Ltd Technical Support:浙江七米


          No. 3, Muyu new village, Jintang town, Dinghai district, Zhoushan, Zhejiang province





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