The combined working quality of the two parts of the extruder screw and barrel has an important influence on the plasticization of materials, the quality of products and the production efficiency. Their working quality is related to the manufacturing accuracy and assembly gap of the two parts. When the two parts are severely worn and the output of the extruder decreases, the screw and barrel should be repaired or replaced.
Causes of damage to the screw and barrel
(1) Improper selection of materials for manufacturing screw and barrel will make the working strength of the two parts insufficient and shorten their working life.
(2) The heat treatment hardness of the working surface of the screw and barrel does not reach the required value, which will accelerate the wear of the two parts.
(3) Due to the low machining accuracy of the screw and barrel, poor straightness, improper placement of the screw, or low installation accuracy, the screw and barrel will touch, which will make a friction sound and make the two wear quickly when rotating.
(4) If the screw and barrel are improperly operated, and the process temperature control is unstable, the extruded material is often decomposed. For example, when PVC is decomposed, a large amount of HCI gas is released, which intensifies the corrosion of the parts.
(5) The screw extrudes the material in the barrel and rotates, and there is a friction between the three for a long time, so that the inner diameter of the barrel gradually increases, and the outer diameter of the screw gradually decreases. In this way, the gap between screw and barrel will gradually increase with the gradual wear and tear of the two.
(6) In the material extruded by the screw and barrel, if there are fillers such as calcium carbonate or glass fiber, it will aggravate the wear of the screw and barrel.
(7) During the extrusion production process, due to the low process temperature or the mixing of metal foreign matter in the barrel, the working torque of the screw will suddenly increase. This torque exceeds the strength limit of the screw and will cause the screw to twist and break.