Why does an extruder screw play an essential role in the recycling process?

An extruder screw makes it possible to process a wide range of materials efficiently.
In this article, we'll take a closer look at

• the composition of an extruder screw and
• which elements have a significant influence on the recycling process.

The extruder screw is a central component in extrusion systems. It processes plastics such as PE, PP, PS, PC and PA 6.0 efficiently and reliably. The central task of an extruder screw is to melt and move the material on through the recycling process.

It consists of a shaft that visually resembles an oversized screw that rotates in a cylinder. The melted material is moved through the extruder by the screw. In the process, the screw creates pressure in the cylinder, enabling the material to be homogenized.

The extruder screw itself is equipped with various sections or zones, each of which fulfils specific functions. Typical zones include:

Feed zone

Melting zone

Mixing and homogenization zone

Forming and output zone

The material is fed into the extruder hopper. There, it is caught by the rotating screw and conveyed further along the cylinder. During conveyance, the material is melted and homogenized by rotating motion, pressure and heat in the extruder. During this process, the melt passes through the forming and output zone into the next component of the recycling machine.

One of the extruder screw’s greatest strengths is its ability to process many different materials. From films to flakes to regrind material, it can efficiently process a wide variety of materials and material forms. This significantly increases the versatility and flexibility of recycling plants.

By melting the plastic material in the extruder screw, other solids such as wood, paper, sand, etc. can be effectively removed in a subsequent filtration process. This improves the quality of the end products.