Working Principle Of A Twin Screw Extruder

Introduction

A twin screw extruder is a machine used for processing plastics and blending different  materials, transforming them from a solid state to a molten state andshaping them through an extrusion die to achieve the desired form.Twin screw extrusion machine is a widely used industrial process for producing a wide range of products from food, plastic, and chemical industries.

Working Principle

The twin screw extrusion machine consists of two parallel screws that rotate in opposite directions and are housed inside a barrel.The process is based on the principle of plasticization and homogenization of the raw material in the presence of heat and pressure.                                                     

The raw material is fed into the barrel through a hopper and is transported through the screws towards the end of the barrel. The screws are designed in such a way that they compress and heat the raw material to a specific temperature range, thus converting it into a homogeneous mixture. This mixture is then forced  through a die and is cooled to form the desired product. The twin screw design provides a high degree of mixing and kneading action, which enhances the plasticization and homogenization of the raw material.

Basic Steps in a twin screw compounding process

1. Feeding: Raw materials are loaded into the extruder's feed hopper. In the feeding zone, two screws push the raw materials from the feed area towards the processing area.

2. Conveying and Mixing: The rotation of the screws transfers the raw materials through the screw channels between the two screws. Within these channels,  the raw materials are gradually heated and melted while also being thoroughly mixed.

3. Heating and Melting: The extruder's screws and barrel are heated through a heating system, transforming the raw materials from a solid to a molten state. During this process, the temperature of the raw materials increases, making them pliable and easy to process.

4. Compression and Venting: The raw materials are compressed by the action of the screws and vented through gaps between the screws. This helps to eliminate gases and vapors from the raw materials, preventing the formation of bubbles during extrusion.

5. Extrusion: The molten material is forced through an extrusion die, shaping it into the desired form such as rods, tubes, sheets, etc. The extrusion die typically has a mold that controls the shape and dimensions of the extrudate.

6. Cooling and Solidification: After exiting the extrusion die, the extrudate is rapidly cooled and solidified using a cooling system. This helps to maintain the desired shape and properties.

7. Cutting and Collection: The cooled extrudate is cut into the desired lengths and can then be collected, packaged, and further processed.

   
   

In summary, a twin screw extruder employs a continuous process of heating, melting, extrusion, and cooling to transform solid raw materials into plastic products or other pliable material products. This working principle makes it a key equipment widely used in plastic processing and manufacturing.

Twin screw extruders from China enjoy a good balance of price and performance.

Nanjing jieya is a leading Chinese co rotating twin screw extruder manufacturer for compounding and pelletizing.our products include lab extruder /twin screw extruder/single screw extruder with diameter from 20mm to 135mm.

We dedicate to provide a better soloution for customers all over the world. We are looking forward to your quotation.