The screw and barrel of the extruder are one of the souls of the extruder, and their combination is related to the working quality of the extruder, the plasticizing capacity of the material, and the production efficiency. Therefore, when the extruder screw and barrel are severely worn, it will affect the extrusion output. This shows that the maintenance and repair of the screw and barrel are important! It is same for our plastic filament extruders for broom, brush, synthetic hair, eyelashes, rope, cosmetic brush, paint brush, safety net etc.
1. Reasons for damage to screw and barrel
1). The screw rotates in the barrel, and the friction between the material and the two causes the working surfaces of the screw and barrel to gradually wear out, the diameter of the screw gradually decreases, and the inner diameter of the barrel gradually increases.
2). If the material contains calcium carbonate and glass fiber, it will accelerate the wear of the screw and barrel.
3). Because the material is not uniformly plasticized or metal is mixed into the material, the sudden increase in the torque of the screw will limit the strength of the screw and cause the screw to twist.
2. Screw and barrel repair
1). The surface of the worn screw should be smoothed and cleaned, and then the wear part should be thermally sprayed with wear-resistant alloy. After spraying, the size of each part of the screw should be larger than the size of the original screw, and then grinding and warping to the required size.
2). If the screw thread part is severely worn, the size is reduced or the damaged part is large, it can be repaired by surfacing welding wear-resistant alloy. Generally, it can be surfacing welded to a thickness of 2-3mm, and then ground to the required size. Surfacing repair method.
3). If the size of the screw does not change much after wear, the surface can also be repaired by hard chromium plating. The hard chromium layer is wear-resistant and corrosion-resistant, but if the base is not treated well or the chrome layer is thick, the chrome layer is easy to fall off.
4). For screw torsion, when a new screw is to be manufactured, the machining outer diameter of the screw should be determined according to the actual inner diameter of the barrel and the theoretically required matching clearance. The outer diameter deviation is processed according to Table 5-1.
5). To repair the screw whose diameter has become smaller due to wear, the surface of the worn screw should be smoothed and cleaned, and then the wear part should be thermally sprayed with wear-resistant alloy. After spraying, the size of each part of the screw should be larger than that of the original screw. Grind and process to the required size. This kind of repair can be carried out in a professional spraying factory and the cost is relatively low.
6). If the thread part of the screw is severely worn, the size is reduced or the damaged part is larger, it can be repaired by surfacing wear-resistant alloy. Generally, it can be surfacing welded to a thickness of 2-3mm, and then ground to the required size. The surfacing repair method is more expensive, so you must carefully consider the choice.
7). If the size of the screw does not change much after wear, it can also be repaired by hard chrome plating on the surface. The hard chrome layer is wear-resistant and corrosion-resistant, but if the substrate is not treated well or the chrome layer is thick, the chrome layer is easy to fall off.
Post time: Nov-30-2020