Something about Co-rotating Twin Screw Extruder

The advantage of co-rotating twin-screw extruder is for different mixing requirements of materials, a limited number of types of screw elements and barrels are possibly used for various arrangements and combinations to optimize the design.

Structure of Same-direction Twin-screw Extruder:

1. Extrusion system: barrel, screw and head connector (including perforated plate)
2. Feeding system: hopper, feeder and feeder drive
3. Transmission system: motor, gearbox and thrust bearing
4. Heating and cooling system: There are heating and liquid cooling channels inside the barrel
5. Control system: automatic control of the entire extrusion system
6. The function of each part is similar to the single screw extruder, but the structure is much more complicated.

The structure and function of co-rotating twin-screw extruder are very similar to those of single-screw extruder, but there are great differences in the working principle. They are mainly referred to the following aspects:

1. Forced feeding. At the intermeshing point, the material movement between the two screws is in opposite directions. One screw pulls the material into the intermeshing gap, and the other screw pushes the material out of the gap. As a result, the material moves from one screw to the other and then enters into anther screw groove. Thus the material is forcedly conveyed toward the extruder head along the screw.
2. Homogenization and mixing. The co-rotating twin screw has a small clearance at the intermeshing point. The intermeshing zone has a higher shearing speed and a larger shearing force so the mixing effect is far better than that of a single screw or of a counter-rotating twin screw extruder.
3. Self-cleaning. Co-rotating twin-screw extruder with its special screw structure can scrape away any accumulated material on the screw so that the residence time of the material is very short, and it is not easy to get partially degraded.
4. Plasticization of materials. The size of the screw clearance has a great influence on the plasticizing quality of the material. The smaller the gap, the greater the shear force, but the amount of material passing through is less; while the larger the gap, the greater the amount of material passing through, but the shear force is less.
5. Compression of materials. There are many more methods to compress materials by the co-rotating twin-screw extruder, and the overall effect is good.
6. Feeding method. The co-rotating twin-screw extruder requires uniform and quantitative feeding, and uses a metered hungry feeding method.
7. Venting. Because it is hungry feeding, a large lead screw conveying element can be used to make the screw groove in an under-filled state and a zero pressure state, so that an exhaustion section can be arranged.

The co-rotating twin-screw extruder doubles the output of other similar products and saves 50% of electricity. The main performance parameters of this machine have reached the advanced international level, and the products have filled the gaps at home and abroad. In addition to energy saving and power saving, it also has ultra-high output, good mixing and dispersing effect and good plasticity, low shear, low temperature processing, high proportion of calcium carbonate filling and 100% recycled materials applicable for reproduction and long life.