01How the process works
A screw extruder melts the compound and pushes it through a die; the product is sized in a calibrator, cooled in water baths, pulled by a haul-off and cut. Inline gauges measure wall thickness and diameter.
Wall thickness, ovality, surface quality and material composition are the main controls. For pressure pipes, hydrostatic and long term tests prove the compound and process.
- Compound. Material and additives dosed.
- Extrusion. Melt pushed through the die.
- Calibration and cooling. Shape fixed in vacuum calibrator and tanks.
- Haul-off and cutting. Product pulled and cut.
- Testing. Dimensions, pressure tests, marking.
02What typically goes wrong
| Defect | Typical cause | How it is found |
|---|---|---|
| Wall thickness variation | Die centring, melt temperature | Ultrasonic gauge |
| Ovality | Cooling, handling | Diameter tape, gauge |
| Surface roughness and die lines | Die condition | Visual |
| Voids and bubbles | Moisture, degassing | Visual, section |
| Low pressure resistance | Compound, processing | Hydrostatic test |
| Wrong marking | Printer set-up | Visual |
03Where an inspector should look
01
Before production
- Compound certificate
- Die and calibrator set-up
02
During production
- Inline wall and diameter readings
- Melt and bath temperatures
03
After production
- Hydrostatic tests per lot
- Dimensions and marking
- Bundling and capping
04Standards and references
EN 12201 and ISO 4427 (PE pipes), EN 1452 (PVC-U pipes), EN 12608 (PVC window profiles).
Standards are named for orientation. The applicable edition and acceptance criteria are those in your contract and specification.
05How we support buyers of plastic extrusion parts
Independent Quality ControlIncoming, in-process and final quality control performed independently at the supplier, with measured results and clear acceptance decisions.
Pre-Shipment InspectionFinal random or complete inspection of finished goods before shipment: quantity, conformity, workmanship, packing and marking.