The extruder is the main machine of the extrusion molding line. Its role is to plasticize, convey the material and provide the required pressure for the product. Extruders exist as the leading equipment for processing many types of products and have been widely used in many countries and China and have become a series of mechanical products with series and specifications. There are many types of extruders. Different extruders are available, and the relevant parameters indicate their range of use and performance indicators. So how many types of the extruder are there?
Extruders can be classified as twin-screw extruders, single-screw extruders, and, rarely, multi-screw extruders and screwless extruders. The screw extruder relies on the pressure and shear force generated by the rotation of the screw, which allows the material to be wholly plasticized and uniformly mixed. The extruder is formed through the mouth die.
The classification of extruders is as follows.
1, according to the number of screws, can be divided into single-screw, twin-screw, and multi-screw extruder.
2, according to whether the exhaust can be divided into the exhaust and non-exhaust extruder.
3, according to the position of the screw, can be divided into vertical and horizontal extruders.
In general, the most basic and ordinary among the extruders is the single-screw extruder. Its main components include transmission, charging device, barrel, screw, head, mouth die, and other six parts. The twin-screw extruder has the characteristics of less heat generated by friction, more uniform shear to which the material is subjected, larger conveying capacity of the screw, more stable extrusion volume, prolonged stay of the material in the barrel, and uniform mixing, etc. It is also more widely used.
Differences between the two types of extruders：
Single-screw machine and twin-screw machine: one is a screw, the other is two screws, a motor drives both, the power varies depending on the screw, the output is related to, and screw, the production of a single screw is only half.
The twin-screw extruder has forced extrusion, high quality, wide adaptability, long life, low shear rate. The material is not easy to decompose, mixing and good plasticizing performance, direct powder molding, and other characteristics. It has temperature self-control, vacuum exhaust, and other devices suitable for producing tubes, plates, shaped materials.
Single-screw extruder, whether as plasticizing granulation machinery or molding processing machinery, occupies an important position. At present, single-screw extruder has a significant development. The main sign of the development of a single-screw extruder is the development of its key components – screw. In recent years, people have conducted a lot of theoretical and experimental research on the screw, and now there are nearly 100 kinds of screws. Common separation types are shear type, barrier type, diversion type, and wave type.
From the single-screw development, although the single-screw extruder has been close to perfection, with the continuous development of polymer materials and plastic products, there will be more characteristics of the new screw and special single-screw extruder. In general, the direction of the single-screw extruder trend to high-speed, high-efficiency, specialization.
Twin-screw extruders have good feeding characteristics, suitable for powder processing, and have better mixing, exhaust, reaction, and self-cleaning functions than single-screw extruders. They are characterized by their superiority in processing plastics with poor thermal stability and co-mingled materials. In recent years, domestic and foreign twin-screw extruders have been a significant development. Various forms of twin-screw extruders have been serialized and commercialized, producing more manufacturers, the development of more and more perfect.
The Food Extruder Machine currently on the market is mainly a twin-screw extruder that can produce a variety of uncoated, coated or sandwich cereal snacks with various formulations and shapes. Food Extruder Machines use twin-screw extrusion technology and are highly flexible. They can be easily converted into machines for processing new products such as sandwich products, cornflake snacks, or crumb snacks with the easy addition of some auxiliary equipment.
Food Extruder Machine uses corn, rice, wheat, oats, barley, etc., as raw material to make snacks. The grains are cooked in the extruder by the friction between screw and barrel. And the forming is done at the die face tool. The combination of die apertures determines the shape of the product, and by adjusting the dies in the extruder,it can provide a variety of shapes such as spheres, tubes, bars, rings, fruit rings, stars, wheels, flowers and hearts.
Among several extruders, screw extruders are widely used , and twin-screw extruders are the best extrusion equipment for foodstuffs, bringing many conveniences and high economic benefits to food processing enterprises. It is believed that with the development of science and technology, extruders will have a broad development prospect.