Case Study: PVC Waterstop Profile Extrusion Line with Twin Screw System and PLC Control Lifts Output and Yield
نشرت في: November 4, 2026
Project Background
The customer is a PVC waterstop profile manufacturer supplying construction joint sealing products to infrastructure and building projects. Waterstop profiles are demanding to extrude: the cross-section is wide and thin-walled in places, the profile must stay dimensionally stable over long runs, and any variation in screw speed or melt temperature shows up immediately as a rejected length. Before the upgrade, the customer ran an older single-screw line that had become the bottleneck of the whole plant.
The brief given to our engineering team was specific: raise stable output, cut scrap on start-up and during running, and reduce the operator’s dependence on manual adjustment — without changing the profile design that had already been approved by the customer’s project clients.
Challenges on the Existing Line
- Unstable output: single-screw plastication fluctuated with regrind ratio, so line speed had to be trimmed constantly.
- High scrap rate: start-up scrap and mid-run dimensional drift accounted for a large share of material loss.
- Manual temperature control: barrel and die zones were adjusted by hand, so quality depended heavily on operator experience.
- Frequent die cleaning: carbon build-up in the die head required repeated shutdowns and re-calibration.
- Hard changeover: switching between waterstop sizes took a long time and produced a large transition scrap block.
Equipment Configuration Supplied
The line was rebuilt around a twin screw extrusion system, with the die and downstream equipment matched to the waterstop profile family.
| Section | Configuration | Role in the Line |
|---|---|---|
| Extrusion unit | Twin screw extrusion system with matched screw geometry for rigid PVC compound | Stable plastication and pressure build-up, consistent melt quality on virgin and regrind blends |
| Control system | PLC with touch screen HMI, multi-zone temperature control and recipe storage | One-touch recall of proven settings, recorded parameters, less operator judgement |
| Die head / mold | Stainless steel mold for PVC waterstop profiles, flow-balanced for the section | Uniform wall thickness, clean melt channels, longer intervals between cleaning |
| Downstream | Calibration and cooling tank, haul-off, cutter | Dimension control and steady line speed after the die |
Capacity and Yield Results
After commissioning and a two-week stabilisation period, the line was compared with the previous configuration running the same waterstop section and the same compound formulation.
| Indicator | Previous single-screw line | New twin screw line |
|---|---|---|
| Stable hourly output | Baseline | Increased by roughly one third at the same profile |
| Scrap rate | High, driven by start-up and drift | Substantially reduced; start-up scrap shortened |
| Dimensional consistency | Frequent manual correction | Held within tolerance through the full shift |
| Operator dependency | Experienced operator required | Recipe recall on touch screen, junior operators can run the line |
| Die cleaning interval | Frequent shutdowns | Extended interval, less downtime |
| Size changeover | Long, high transition scrap | Faster, transition scrap reduced |
Because output and yield moved in the same direction, the effective gain per shift exceeded the machine-level improvement: more good metres per hour, and fewer metres sent back to the granulator.
Commissioning and Support
Installation and commissioning were carried out on site, followed by operator training covering recipe set-up, temperature zone management, die cleaning procedure and routine maintenance points. The PLC touch screen stores the proven parameter set for each waterstop size, so restarting a known product is now a matter of recall rather than re-tuning.
Customer Feedback
The customer’s production manager summarised the change simply: the line now produces the same profile with less attention, less scrap and more metres per shift, and new operators reach stable production far faster than before. The approved profile design was kept unchanged, so no re-approval with the project clients was needed.
Conclusion
For PVC waterstop producers, extrusion stability is the whole business case: unstable plastication turns directly into scrap and lost line time. Matching a twin screw extrusion system with PLC touch screen control and a properly flow-balanced stainless steel mold converted a bottleneck line into a predictable one — higher output, better yield, and a process that no longer depends on one experienced operator.
If you are producing PVC waterstop profiles and want a line assessment against your current output and scrap figures, send us your section drawing and target capacity.
