Screw Extrusion

One of the most popular process to transform fluoropolymers.

Screw Extrusion as a first step of the extrusion the raw material usually in the form of granules it is put into the hopper and then forced into a heated chamber. The rotating screw forces the plastic resin forward into the barrel that is heated to the desired melt temperature and pressure depending on the resin.

The temperature must be set above the melting point of the polymer which is being processed. It is important a strict control of the temperature to avoid overheating and degradation of the polymer.

The die at the end of the chamber will give the desidered form, usually a rod, a tube or a specific profile. When designing the die heavy consideration has to be placed on how the plastics will flow through; small faults can result in warping of the final plastic product.

There needs to be consistency throughout the flow of the die to keep design integrity for the end product.
The next step is the cooling process which can be in a water bath or by other means depending on the plastics. Since all plastics and most of all fluoropolymers are excellent thermal insulators the cooling happens at a much lower pace than metal.

The releasing of the built up temperature to reach the temperature of the final shape is another key step which define the quality of the extrudate.

Cutting the extrudate to the desired length is the final step of the process.