PVC Cable Trunking Extrusion Line

Our SJZ series parallel twin-screw extruders (SJZ51, SJZ55, SJZ65) are specially designed for high-efficiency production of PVC cable trunking (also called cable tray, wiring duct or slotted conduit). These lines are widely used for:
Electrical installations in residential and commercial buildings
Cable management systems in data centers
Industrial control cabinets and switchgear
Public infrastructure (airports, hospitals, subway stations)
Real case: A Malaysian electrical accessory manufacturer upgraded from a single-screw line to our SJZ55 model. At an output of 120 kg/h (within the 100–150 kg/h range), they reduced unit cost by 18% while maintaining precise slot dimensions for snap-fit covers.

High energy efficiency – lower energy consumption per kg: e.g., SJZ65 consumes 37 kW for 150–200 kg/h output (approx. 0.21 kW/kg), outperforming many conventional designs.

Wide processing window – parallel twin-screw geometry ensures excellent PVC mixing and plasticizing ability, enabling stable production of thin-wall (0.8 mm) and thick-wall (3 mm) trunking.

Scalable output – from small workshops (SJZ51) to large-capacity factories (SJZ65), the series matches different production scales.

Durable screw and barrel – nitrided steel construction, optional bimetallic lining, extending service life by 30% when processing recycled PVC or high calcium carbonate filled formulations.

Case study: A Turkish profile manufacturer used an SJZ51 to continuously produce 25×25 mm small trunking at 95 kg/h, running for 8 months without screw wear issues – saving 15 kWh per ton compared to their old extruder.

To ensure each production line complies with international standards (CE, ISO 9001), we implement a 4-stage quality control plan:

Stage 1 – Raw material and component inspection

Verify alloy composition of screw/barrel using a spectrometer.

Test heating elements and gearbox for power rating and noise (<75 dB).

Stage 2 – In-process control

Screw concentricity within 0.02 mm (laser alignment check).

Calibrate barrel heating zones with thermocouple simulator, accuracy ±1°C.

Stage 3 – Factory acceptance test (FAT)
Each line runs for ≥6 hours using actual PVC trunking material. We measure:

Output stability (fluctuation <3% of rated capacity).

Trunking dimensional accuracy (EN 50085 standard): width tolerance ±0.2 mm, slot pitch tolerance ±0.1 mm.

Die head pressure fluctuation (<5 MPa).

Stage 4 – Post-installation validation

On-site trial run using customer's formulation.

24-hour continuous operation monitoring – record vibration (<4.5 mm/s), motor current and melt temperature.

Example: Before shipping an SJZ55 line to Chile, we simulated high temperature (40°C) conditions and performed a 150 kg/h test – all trunking passed drop weight impact test (5 J) and hot set test (<25%).

Q: Can I produce both solid and slotted trunking on the same line?
A: Yes. By changing the calibrator and cooling tank, our SJZ series can easily switch between slotted (for cable trunking) and unslotted (for conduit) profiles. The twin-screw design supports fast recipe adjustments – typical changeover time is 40 minutes.

Q: My target output is 120 kg/h. Which model should I choose – SJZ55 or SJZ65?
A: SJZ55 is the most cost-effective (rated 100–150 kg/h). However, if you plan to increase capacity within 2 years, or process highly filled formulations (e.g., 40 phr CaCO₃), then SJZ65 offers higher torque and screw cooling to avoid thermal degradation while maintaining a stable 120 kg/h output.

Q: What is the typical screw wear life when processing recycled PVC?
A: With a standard nitrided screw (HV 950–1000) and clean recyclate (metal impurities <0.5%), expect 8,000–10,000 hours. For high-abrasion applications (e.g., wood-plastic composite trunking), we recommend a bimetallic screw (HRC 58–62) – life can be extended to 15,000 hours.

Q: How do I ensure consistent trunking slot dimensions?
A: Our extruder is combined with a closed-loop vacuum calibration tank featuring 6 independent cooling zones. In addition, the SJZ series has a melt pressure feedback system that automatically adjusts screw speed – keeping slot width within ±0.15 mm even when batch viscosity varies.

Q: Does the SJZ51 support off-line punching/slotting?
A: The line is only the extrusion system. For slotted punching, we recommend a separate in-line rotary punching unit (optional) that synchronizes with the haul-off speed. Many customers pair the SJZ51 with a servo-driven punching unit to produce slots at 15 mm pitch with line speeds up to 5 m/min.