What are the classification of screw extruders and common problems?


The screw extruder mainly processes plastic products to […]

The screw extruder mainly processes plastic products to produce products that meet the requirements. There are many types of this equipment, divided into different types according to different categories. When using the equipment, choose the right equipment and be aware of some common problems.

What are the classifications of screw extruders?
1. According to the function of screw machine: it is divided into continuous extrusion and discontinuous extrusion.
2. Classified according to the number of screws: Divided into: single screw, twin screw and triple screw (multi-screw) extruders. Classified by screw shape: divided into integral screw and building block combined twin screw (multi-screw).
3. The twin-screw extruder can be further divided into: parallel twin-screw extruder and conical twin-screw extruder; and parallel co-rotating and parallel counter-rotating twin-screw extruder.

What are the common problems of screw extruders?
1. The physical properties of the product are reduced
When plastic melt is extruded by screw, because the relative gap between the screw and barrel of the traditional extruder is too large, too much countercurrent phenomenon occurs, which causes repeated shearing of each component in the formula, and excessive shearing rapidly increases the melting. The internal shear heat of the body.
2. Particle defects
Due to the large extrusion gap, the melt will flow backwards, which will reduce the screw extrusion and conveying capacity per unit time, and the head pressure will be low; the particles will not be dense. The countercurrent causes repeated shearing, which virtually consumes too much electric energy and increases the cost of granulation.
3. The surface of the particles is not bright
The barrel is the core component of the extruder. The American arc plastic machine has greatly improved the accuracy of the flow channel in the extrusion system. The barrel and screw are made of special imported plastic machine special alloys.
4. Poorly dispersed powder
The arc of the thread sleeve tends to the theoretical design value; the kneading space is reduced to a greater extent, and the mixing function of the thread sleeve is improved; application analysis, for example: two white masterbatches of PP and PET, require not only good dispersion, but also high viscosity.