What Is The Difference Between Single Screw And Twin Screw Extruder

At present, the extruders in the plastic industry at home and abroad are roughly divided into two categories, one is a single screw extruder and the other is a twin screw extruder. Because these two types of machines have their characteristics, they are widely used in the plastics industry. So what are the advantages of these two extruders, and what are the differences between them? After reading this article, you will no longer be confused.

Introduction and application of single and twin screw extruder

Single screw extruder introduction

As the name suggests, a single screw extruder machine has a screw in the barrel.

Main applications of single screw extruder

Mainly used in the extrusion of pipes, sheets, plates, and profiles, and granulation of some modified materials.

Twin screw extruder introduction

In the same way, the twin screw extruder machine has two screws in the barrel.

Classification of twin screw extruder introduction

Compared with single screw extruders, the classification of double screw extruders is relatively complicated, and there are more classification methods.

1. According to the position of the two screws, it is divided into the parallel twin screw extruder and conical twin screw extruder;

2. According to the degree of meshing of the two screws, it is divided into the intermeshing twin screw extruder and non-intermeshing twin screw extruder;

3. According to the rotation direction of the two screws, they are divided into co-rotating twin screw extruders and counter-rotating twin screw extruders. In the counter-rotation, they are divided into inward twin screw extruders and outward twin screw extruders;

4. According to the screw rotation speed, it is divided into the high-speed twin screw extruder and low-speed twin screw extruder;

5. According to the structure of the screw and barrel, it is divided into the integral twin screw extruder and combined twin screw extruder.

Twin screw extruder applications

The twin-screw extruder is mainly used for the granulation of fiber reinforced, flame retardant, improved filling and other modified plastics, the compounding and extrusion of thermosetting plastics, and the extrusion and granulation of hot melt adhesives and PU.

Difference between the single screw and twin screw extruders

After briefly introducing the single and twin screw extruder above, let's take a look at the specific differences between the two extruders in terms of price, operability, and screw.

1. Single screw extruder is cheaper

Single screw extruder has a simple structure and low price;

The twin screw structure is complex and the price is high. The twin screw extruder is about twice as expensive as the single screw extruder. The details vary by manufacturer and model.

2. Single screw structure is simpler

To be honest, for the operation, the difference between the two extruders is not very big. However, the process and structure of a single-screw extruder are relatively simple, while the process and structure of a twin screw extruder are more complicated.

3. The twin screw extruder can freely combine screws

Twin screw threads can be freely combined according to material requirements;

The single screw extruder is relatively rigid and cannot be combined with screws.

4. Twin screw extruder is more efficient

The twin screw extruder has a large output, fast extrusion speed, and low energy consumption per unit output, while the single screw is worse. The efficiency of a twin-screw extruder is about 1 times that of a single screw extruder. The specific difference depends on the manufacturer and model.

5. Twin screw extruder has strong compounding and plasticizing ability

To put it simply, the single screw is suitable for the plasticization and extrusion of polymers and the extrusion processing of pellets, such as molding, film blowing, injection molding, etc., with a wide range of materials;

The twin screw extruder has good compounding and plasticizing ability, which is more suitable for plastic modification. And the twin screw extruder can produce two-color materials.

6. Single screw extruder is easy to maintain

In terms of maintenance, the single screw extruder is simpler than the twin screw extruder, because the structure of the single screw extruder is relatively simple and easy to repair.

7. Transport mechanism

The conveying of the single screw extruder mainly depends on the friction force generated between the material and the barrel. The counter-rotating twin screw extruder is forward conveying, which has the effect of forcibly pushing the material forward, and the counter-rotating twin screw extruder also produces a shearing effect on the material at the meshing position of the two screws.

8. Velocity field

The speed distribution in the single screw extruder is relatively clear and easy to describe, while the situation in the counter-rotating twin screw extruder is quite complicated and difficult to describe. This is mainly because the screw has an intermeshing zone. The complex flow that occurs in the intermeshing zone has many advantages such as sufficient compounding, uniform heat transfer, strong melting ability, and good exhaust performance. However, it is difficult to accurately analyze the flow state in the engagement zone.

Do you now know how to better display the real performance of the extruder? Chuangbo is a professional twin screw extruder manufacturer and supplier in China. We can provide customers with different extruders with excellent performance, such as masterbatch extruder, PVC compounding, thermoplastic elastermor, reaction extrusion line, devolatilization extruder, pelletizing system, etc.