Higher output in rigid PVC corrugated pipe extrusion

A manufacturer of systems and components for electrical installations needed to improve the performance of an Ø80 single-screw extruder used to produce black corrugated pipes from rigid polyvinyl chloride (PVC). The original plasticising unit provided insufficient output. Increasing the screw speed raised production, but also caused particles of incompletely plasticised material to appear in the pipe. This reduced product quality and, in some cases, resulted in pipe breakage. The objective was therefore to increase productivity while retaining proper control of plasticisation. This was particularly important because rigid PVC is sensitive to overheating and unsuitable processing conditions. Euroviti addressed the requirement by developing a new plasticising unit adapted to the material, the existing machine and the customer's production target, rather than reproducing the original configuration. A specially designed screw profile combined with a grooved-feed barrel enabled an output of approximately 95 kg/h at a screw speed of 30 rpm, while maintaining satisfactory extrudate quality.

Plasticising unit adapted to rigid PVC

The new configuration included a barrel with a grooved feed section and a single-flight screw with an optimised EUV-U-PVC profile designed specifically for rigid PVC processing. The screw was made from EUV41 steel, with wear-resistant hardfacing applied to the screw flights, and received an EUVTiN surface treatment.

The screw geometry was developed to improve material conveying and provide more consistent plasticisation at higher production rates. This approach was intended to prevent incompletely melted particles without exposing the heat-sensitive material to unsuitable processing conditions.

Output of approximately 95 kg/h at 30 rpm

With the new plasticising unit, the customer achieved an output of approximately 95 kg/h at 30 rpm while maintaining satisfactory corrugated pipe quality. The reported results included:

• increased production output;
• more consistent plasticisation of rigid PVC;
• elimination of incompletely melted particles in the pipe;
• fewer defects and related pipe breakages;
• stable extrudate quality.

The project shows that an existing extruder can achieve measurable improvements in productivity, process stability and finished-product quality when the plasticising unit is developed around the characteristics of the processed material and the requirements of the production process.