PTFE Tubing: Process Parameters And Their Impact

PTFE Tubing extrusion is among the most difficult processes within the purview of the polymer space. All polymers have their set of peculiarities and these play a part in things like processing and machining. But PTFE tube comes with different process parameters, and finding the right combination that works consistently is something that not every tube manufacturer will know. Let’s find out some of the parameters here followed by PTFE hose manufacturers.

 

Handling: Handling resin is among the most important but easily overlooked part of PTFE processing. While many resin manufacturers give out layout guidelines for providing the shear on the resin before the processing starts these are more important for the tubing. 

Blending: The parameters about blending include the type of extrusion aid used. The blending needs to be done in the correct manner, the final extrude will either too soft or too dry. Furthermore,  the blend has to be uniform, the preform billet will have uneven densities, causing issues during the extrusion.

Preforming:  Preforming is done to create a shape that can fit into an extruder. 

• Preforming has two functions: first, it provides a solid shape and second, it also removes any air pockets form within the material. The process needs to be done in a way to keep too little pressure and not go for enough venting of the air inside the material. 

Extrusion: While extrusion is understandably the most important step, by the time the preform billet is loaded into the extruder, the preceding processes have already defined a lot of the tube’s final characteristics. Extrusion gives it the final shape and this process helps maintain both adequate pressures on the billet while maintaining the concentricity of the final tube. 

Sintering: Heat the tube in a way that the temperature needs to account for both a drying section and the sintering section. The drying section should be warm enough to evaporate all the traces of vapor from the tube. At the same time, if it is too warm, the vapors may start getting ignited. If the tube gets heated too quickly, there is a chance of over-sintering. Too much heat can cause dimensional deviations. In PTFE. Therefore the temperature must turn out the PTFE in a ‘gel state’ just before it leaves the sintering chamber and then cool down at room temperature.

The PTFE tube also undergoes a process called pigmentation, the addition of anti-static fillers also extrusion of specific profiles. All the above processes need to be modified to allow a proper end-result.