How to choose the screw of plastic extruder?

​The main part of the plastic extruder is the screw barrel, which also has an important influence on the plasticization, extrusion, and molding of plastics. Therefore, reasonable selection of screw structure and parameters is one of the prerequisites for obtaining ideal product quality and output. In order to meet the needs of different plastic processing, there are many kinds of screw structures, and there are three common types: gradual change type (equal depth and unequal distance or equal distance and unequal depth), sudden change type, torpedo head type, etc. So, how to choose the screw of the plastic extruder?

The selection of the screw structure of the plastic extruder is mainly determined according to the physical properties of the plastic and the production technical specifications of the extruder.
1. The softening of non-crystalline polymer is completed in a relatively wide temperature range, and the equidistant gradual change screw is generally used. The melting temperature range of crystalline polymers is relatively narrow, and an equidistant mutation screw is generally used.
2. On small plastic extruders, such as the o45 extruder, the screw adopts a full-threaded type with equal distances and different depths. The long diameter of the screw is relatively small, and it is mainly used to extrude small-section insulating layers and sheath layers. The extrusion speed is faster.
3. The medium-sized screw adopts a full-thread type with equal distance and gradual change in thread depth. Its long diameter is larger than that of the small screw, and the pitch of the thread is equal, from shallow to deep from the root. The thread at the end of the thread is deeper, and the thread at the opposite part is shallower, so that there are more plastic extrusion stars, without affecting the strength of the screw, the extrusion speed is fast, and the plastic is well plasticized. It is generally produced by small and medium-sized plastic extruders. Ideal screw for insulation and sheathing.
The above content is compiled and published by TENGDA extruder manufacturer, I hope it will be helpful to everyone.

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