The moisture contained in the plastic of the rod barrel attachment has a certain influence on the wear of the screw surface. If the plastic does not completely remove the moisture before the injection, the residual moisture enters the compression section of the screw, and becomes a "steam particle" with high temperature and high pressure which is melted and mixed in the molten plastic. With the advancement of the screw in the injection process, from the homogenization section Up to the head of the screw, these "steam particles" are relieved and expanded during the course of the shot, like a fine impurity of hard particles, which causes friction damage to the wall surface.
Alloy steel is currently the most common screw material. Other commonly important screw materials are stainless steel (Gr18MoV) and tool steel. The choice of materials generally depends on the following factor 1: Yield strength. 2: Hardness. 3: Wear resistance. 4: Corrosion resistance. 5: Easy to process. 6: The cost of the material.
The bolts are optimized by a separate screw and mixing element. The barrel is optimized with a grooved barrel and an extended feed section. Through the combination of a split screw and a grooved barrel, the following advantages can be obtained: the melting process of the material is optimized to increase the extrusion yield. The extrusion of the material melt at a lower temperature is achieved. The material is well homogenized by the shear action determined in the isolation gap. The melt plasticization process is controlled, that is, only particles smaller than the isolation gap can enter the melt channel. It provides a wide range of processing for different materials and is suitable for various polyolefin raw materials, especially suitable for HDPE, PP, ABS pipe raw materials.
