Principle and function of twin screw extruder

How it works

Obviously, the material will flow from the high pressure area to the low pressure area in two directions: one is that the wear of the square screw will be reduced as the screw rotates, and the material will be transported, sheared, mixed and heated by the barrel shell in this way.Under the action of high pressure, it is matured and then squeezed out of the cylinder.

The counter-rotating twin-screw extruder generally uses two screws with the same size but opposite thread directions. The difference between the inward rotation and the outward rotation is that the position of the pressure zone is different. The pressure generated by the inward rotation of the twin-screw is high and low. When the material passes through the twin-screw, a very high pressure will be generated at the inlet, which will make feeding difficult. At present, this inward reverse rotation type is rarely used; the pressure generated by the outward rotation of the twin-screw is high and low, which is conducive to feeding. However, compared with co-rotation in reverse rotation, the C-shaped material flow formed in the screw cannot move from one screw to another, the mixing degree of the material is significantly reduced, and its self-cleaning ability does not have co-rotation. The twin screw is effective and stable.

Characteristic effect

The twin-screw extruder has the advantages of strong adaptability, slip conveying and self-cleaning, but its structure is complex, the investment cost is high, and the corresponding maintenance and operation costs are also high. Therefore, twin-screw extruders are generally used in the production of high value-added aquatic and pet feeds, such as the production of eel, soft-shelled turtle and juvenile fish feed, because the prices of these products in the market are sufficient to repay the advantages of twin-screw technology. The cost of manufacturing products; other special aquatic feeds such as particulate aquatic feeds (0.8-1.5mm in diameter), high-fat aquatic feeds and feeds with small production volumes but often changing formulas also need to be produced by twin-screw extruders.

Relatively speaking, this kind of puffing and extrusion equipment, especially the medium-sized double-screw extrusion puffing machine, needs to be adjusted in a wide range during the use process because of its special raw materials and large variation range. Similarly, because its working principle is different from that of a single-screw extruder, there is actually a big difference in the specific structure. So when we purchase and use it, we need to pay attention to some details of it. If you have any doubts when purchasing a twin-screw extruder, please contact us for consultation.