Extruder is a kind of equipment commonly used in processing plastics, rubber, food, medicine, cosmetics and other materials. Its basic principle is to deform the material into the desired shape and size by feeding the material into the screw and barrel for mixing, melting and extrusion.
In this article, we’ll look at three different types of extruders: single-screw, twin-screw, and compound extruders. Among them, the single-screw extruder is suitable for processing low-viscosity materials, the twin-screw extruder is more suitable for processing high-viscosity and high-molecular-weight materials, and the compound extruder combines the advantages of the two and can be used to process various types of materials. At the same time, we will also discuss how to increase the productivity of extruders and look forward to the development trend of extruders in the future.
Comparison of three extruders
Single screw extruder
Working principle
The single-screw extruder is mainly composed of a feed port, a screw, a barrel and a discharge port. When working, the material enters the barrel from the feed port, is pushed by the screw, and after heating and mixing, it is extruded into the required shape and size at the discharge port.
Advantages and disadvantages
The single-screw extruder has simple structure, stable operation and relatively easy maintenance. It is suitable for processing low-viscosity materials, such as PVC plastic pipes, PE packaging films, etc. However, since the mixing effect of the single-screw extruder is not as good as that of the twin-screw extruder, its application range is limited.
Field of application
The single screw extruder is mainly used in the production of PVC water pipes, wire and cable coverings, plastic sheets, capillary tubes, etc.
Twin screw extruder
Working principle
The twin-screw extruder consists of two co-rotating screws and a barrel, one of which is the main screw and the other is the auxiliary screw. When working, the material is further extruded by the auxiliary screw after being heated and mixed by the main screw, so as to achieve better mixing effect.
Advantages and disadvantages
The mixing effect of the twin-screw extruder is good, and the effect is better when processing high-viscosity and high-molecular-weight materials. And the production efficiency is high, which can meet the demand of mass production. However, the twin-screw extruder has a complex structure and is difficult to maintain.
Fields of application
Twin-screw extruders are mainly used in the production of polymer materials such as PVC, PP, PE, ABS, etc., such as plastic pipes, plates, profiled materials, injection plastics, etc.
Counter Rotating Twin Screw Extruder
Compound extruder
Working principle
The composite extruder combines the advantages of single-screw and twin-screw extruders. Screws with different shapes and rotation directions are installed in the barrel to achieve better mixing effect and improve extrusion efficiency.
Advantages and disadvantages
Compared with single-screw and twin-screw extruders, compound extruders are more versatile and flexible, and are suitable for processing various types of materials. However, the compound extruder has a relatively complex structure and is difficult to maintain. At the same time, its cost is relatively higher.
Fields of application
Compound extruders can be widely used in plastics, rubber, food, medicine, cosmetics and other fields, and are suitable for producing products of various shapes and sizes, such as toys, shoe materials, auto parts, etc.
The three types of extruders include single-screw extruders, twin-screw extruders, and hybrid extruders. They have some differences and similarities in structure, working principle and scope of application.
Similarities:
- Extruders heat and compress material to extrude it into shape.
- The main components of the extruder include feeding system, pressure system, heating system, screw, die head and electric control system.
- Extruders can be used in plastics, rubber, food, pharmaceuticals and other fields.
The difference:
- Single-screw extruders have only one screw, twin-screw extruders have two screws, and hybrid extruders have a main screw and an auxiliary screw. This determines their different processing capabilities and efficiencies.
- The processing capacity of the single-screw extruder is relatively weak, and it is suitable for materials with low viscosity, single color or no filler; the processing capacity of the twin-screw extruder is stronger than that of a single screw, and it is suitable for high viscosity, multi-color, multi-level and materials with fillers; the hybrid extruder can flexibly deal with various types of material processing.
- Single-screw extruders and twin-screw extruders are different in terms of processing temperature and pressure, while hybrid extruders combine the characteristics of the two and can adapt to a wider range of processing conditions.
- The cost and maintenance difficulty of the three types of extruders are also different. Single-screw extruders are the simplest, with low cost and maintenance, while twin-screw and hybrid extruders require higher costs and technical levels.
Factors needed to choose an extruder
The nature of the processed material: Different types of extruders are suitable for different types of materials, such as single-screw extruders for low-viscosity, single-color or filler-free materials, and twin-screw extruders for high-viscosity, multi- Colours, layers and fillers. Therefore, when choosing an extruder, you must first understand the properties of the material you want to process, and then choose the corresponding extruder according to its viscosity, color, filler and other characteristics.
Production requirements: Production requirements include product specifications, output, production cycle, etc. For large-scale production companies, it is necessary to choose an extruder with high production efficiency and good stability; for small-batch production companies, you can choose a more economical and practical extruder.
Equipment cost and maintenance difficulty: The equipment cost and maintenance difficulty of different types of extruders are different. In general, single-screw extruders are the simplest, with low cost and maintenance, while twin-screw and hybrid extruders require a higher cost and technical level. When choosing an extruder, it is necessary to comprehensively consider the company’s economic strength and technical level.
Equipment reliability and stability: The extruder is the core equipment in the production line, which has an important impact on production efficiency and product quality. Therefore, when choosing an extruder, its reliability and stability need to be considered. Generally speaking, extruders with high brand awareness and high technical content have relatively more advantages in this respect.
