Manufacturing of plastic tubes and pipes: which moulding/forming process is most commonly employed for continuous hollow sections?

Introduction / Context:
Thermoplastic processing routes differ by geometry and throughput. Long, continuous hollow profiles such as tubes, pipes, and corrugated conduits are key products in infrastructure and packaging, and their economics depend on steady, continuous production.

Given Data / Assumptions:

• Part geometry: long, constant cross-section hollow parts.
• Materials: PE, PP, PVC, PVDF and similar thermoplastics.
• Need for continuous, high-throughput manufacturing.

Concept / Approach:
Extrusion forces molten polymer through an annular die with a calibrated mandrel or pin to create hollow sections. Downstream sizing tanks, vacuum calibration, haul-off, and cutting create finished pipes with tight OD/ID tolerances. Injection and transfer moulding make discrete parts in closed moulds; compression moulding suits thermosets and simple shapes. Therefore, extrusion is the standard method for pipes/tubes.

Step-by-Step Solution:
Match geometry (continuous hollow) to process capability.Identify extrusion as continuous shaping through a die.Confirm auxiliary steps: cooling, sizing, and cutting for final dimension control.

Verification / Alternative check:
Commercial pipe lines run single- or twin-screw extruders with vacuum calibration baths—industry standard.

Why Other Options Are Wrong:
Injection/transfer: discontinuous, closed-mould processes.Compression: mainly for thermosets or flat/simple shapes.

Common Pitfalls:
Assuming injection moulding due to popularity; process must match continuous profile geometry.

Final Answer:
Extrusion