The single screw thread spacing is wide in the front and narrow at the back, while the twin screw thread is basically the same front and back. The working principle of the two is different, so there are great differences in characteristics and feed products. Single screw price is generally lower than twin screw, but twin screw long-term benefit is greater than single screw, the two have different advantages and different use conditions.
When extrusion machine works, powder through the inlet to the feed port, then into the extrusion chamber. Feed be squeezed, sheared, rubed, a variety of action increasing its internal temperature, pressure, material plastic gradually changed gelatinization, finally forced out from the die hole. The volume expansion and water vapor flash of the material occur instantly, forming the expanded feed because of outside die temperature, pressure gradient .
Characteristics
Powder (basic cereal raw material) through high temperature and high pressure, starch material fully gelatinized, improve feed digestibility. Short time high temperature extrusion, on the one hand, it can sterilize and disinfect, on the other hand, it can inactivate the legume anti-nutrition factor and make its plant protein organization also reduce the damage and loss of protein and vitamins and other nutrients.
Scope of application
Suitable for grain meal, bone meal, fish meal, flour, using for make aquaculture feed, pet feed and so on. Suitable for farmers or feed suppliers who usually use common ingredients and have no special requirements for finished feed. 

Principle of twin screw extruder
In the chamber of the twin screw extruder, two screws are placed side by side. According to the relative position of the screw and the rotation of the screw, it is divided into non-meshing synchronous rotation, non-meshing relative rotation, meshing synchronous rotation and meshing relative rotation. The material is rotated by the screw in the sleeve cavity to produce high pressure and low pressure areas, so the material will flow from high pressure area to low pressure area in two directions. One is to form two C-shaped material flows along the inner wall of the sleeve along the rotating direction of the screw, which is the mainstream of the material, and the other is to form countercurrent through the clearance of the meshing part of the screw. Because the left screw pulls the material into the meshing gap, and the right screw pulls the material out from the gap, so that the material is "∞" shape forward, the screw edge not only produces forward transmission, but also allows the material to change direction, and finally forms a different rotation mode of the twin screw.