News

Introduction of extruder screw

update:10-02-2020
abstract:

Modern plastic extruders widely use combined screws, di […]

Modern plastic extruders widely use combined screws, distribution mixing screws, and adding barriers or pins on the screws to improve plasticization, production capacity and product quality. The combined quality of the two parts, screw and barrel, has an important impact on the plasticization of materials, product quality and production efficiency. Their 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 is reduced, maintenance of the screw and barrel should be arranged.

The screw runs under higher load stress, but the running speed is lower, so it operates under high stress and lower alternating frequency. Each start-up operation produces a certain amount of plastic strain. Each time the screw is blocked by a hard object, a certain amount of plastic deformation will also occur. This plastic deformation will cause more serious damage to the screw than when it is started, plus the plastic strain caused by the screw being squeezed and friction for a long time. Under the action of strain, the internal damage of the screw accumulates to a certain extent, and a crack is formed. When the crack propagates to a critical size and the remaining section of the screw is insufficient to bear the screw's operating load, the crack instability and propagation cause a sudden brittle fracture.