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Product Description
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The SJ series single screw extruder is a universal plasticizing machine for PE, PP, PVC, and other thermoplastics. With 8 standard models (SJ-25 through SJ-150) covering 5 to 1200 kg/hr and 4 high-speed SJH models with 38:1 L/D ratio delivering up to 1000 kg/hr, the SJ series serves the full spectrum of plastic processing — blown film, pipe and profile extrusion, sheet calendering, monofilament and strapping tape, cable insulation, hollow blow molding, and compound granulation.
The defining mechanical features are involute hardened gear transmission (EN 24 steel, crowned tooth profile, ground to DIN 6 accuracy) and a nitride-treated 38CrMoAlA screw and barrel pair. These two elements deliver the low noise, high torque transmission, and long service life that make the SJ series the backbone extruder in hundreds of production facilities across Chenxing Machinery's global customer base.
| Parameter | SJ-25 | SJ-30 | SJ-50 | SJ-65 | SJ-75 | SJ-90 | SJ-120 | SJ-150 |
|---|
| L/D Ratio | 25:1 | 25:1 | 25–33:1 | 25–33:1 | 25–33:1 | 25–33:1 | 25–33:1 | 25–33:1 |
| Output (kg/hr) | 5 | 10 | 50–150 | 60–250 | 200–350 | 280–550 | 320–800 | 400–1200 |
| Screw Speed (rpm) | 10–35 | 10–35 | 20–120 | 20–120 | 20–120 | 20–120 | 20–120 | 20–120 |
| Drive Power (kW) | 1.1 | 2.2–3 | 7.5–37 | 22–90 | 55–110 | 37–185 | 75–280 | 90–355 |
| Center Height (mm) | 1000 | 1000 | 1000 | 1000 | 1000 | 1000–1100 | 1000–1250 | 1000–1300 |
| Parameter | SJH-60 | SJH-75 | SJH-90 (Standard) | SJH-90 (High-Output) |
|---|
| L/D Ratio | 38:1 | 38:1 | 38:1 | 38:1 |
| Output (kg/hr) | 300–400 | 400–500 | 600–800 | 850–1000 |
| Screw Speed (rpm) | 120–150 | 120–150 | 120–150 | 120–150 |
| Drive Power (kW) | 90/110 | 132/160 | 250 | 355 |
| Center Height (mm) | 1000 | 1000–1100 | 1000–1250 | 1000–1300 |
Need help with model selection? Contact our engineering team — provide your material type, target hourly output, and product form, and we will recommend the optimal screw configuration and downstream equipment package.
The SJ series offers L/D ratios from 25:1 to 38:1, and Chenxing engineers will configure the optimal value for your material. Why does L/D ratio matter? A 25:1 screw provides three functional zones (feed, compression, metering) and is adequate for general-purpose PE pipe and profile extrusion at moderate output. Stepping up to 33:1 adds a venting/devolatilization section — critical for hygroscopic materials like recycled PP or filled compounds where trapped moisture causes surface defects. The 38:1 SJH high-speed series adds a second metering zone and a Maddock mixing section, enabling 150 rpm operation with full melt homogeneity for thin-gauge film and high-speed cable insulation lines.
The screw itself is machined from 38CrMoAlA alloy steel, nitrided to HV≥900 surface hardness with a 0.5–0.7 mm hardened layer. Barrel bore is centrifugal-cast bimetallic (Xaloy 800 or equivalent) with tungsten carbide wear resistance — standard on all SJ-65 and above models for processors running calcium-carbonate-filled compounds. For manufacturers already operating PVC twin-screw extruders or pelletizing lines, the SJ single screw provides the complementary versatility for non-PVC materials without investing in a second twin-screw machine.
The reducer uses single-stage helical gearing with crowned tooth profile, hardened and precision-ground to DIN 6 accuracy. Compared to the worm-gear reducers still common on budget extruders, the involute gearbox delivers three practical advantages: (1) 96–98% transmission efficiency vs. 70–85% for worm gears — meaning more of your motor's power reaches the screw; (2) thrust bearing (NSK or Timken, customer-specified) rated for 100,000+ operating hours at full back-pressure; (3) noise level below 75 dB(A) at 120 rpm — a critical factor for factories operating multiple extruders in the same bay.
Each barrel zone is independently heated by ceramic band heaters with embedded thermocouple feedback and air-cooling for active temperature regulation. A typical 5-zone SJ-65 configuration for HDPE pipe: Zone 1 (feed throat, water-cooled): 40°C (prevents premature melting and bridging) → Zone 2: 180°C → Zone 3: 200°C → Zone 4: 210°C → Zone 5 (metering): 220°C → Adapter/Die: 215°C. The reverse temperature profile (cool feed throat, progressively hotter toward the die) is a hallmark of correct single screw operation — and one our engineers verify during factory acceptance testing.
A manual or hydraulic slide-plate screen changer is mounted between the barrel end and the die adapter. Screen packs (typically 60/80/100 mesh in a breaker-plate sandwich) remove unmelted particles and contaminants. The manual slide-plate design allows screen change without stopping production: the operator slides the dirty screen pack out of the melt stream while simultaneously sliding a clean pack in — downtime under 30 seconds on the SJ-50 through SJ-90. For high-contamination recycled material, a continuous back-flush screen changer can be specified.
The SJ extruder's standard center height (1000 mm, increasing to 1300 mm on the largest models) and flange-mount die connection are designed for interchangeability with Chenxing downstream equipment. Switch from a pipe die and vacuum calibration tank to a blown film die and bubble cage by unbolting the die flange and repositioning the downstream unit — no custom adapter plates or height adjustment stands required. This modularity allows processors running multiple product types to re-purpose a single SJ extruder across different production lines within the same shift.
Thermoplastic granules or regrind are loaded into the hopper — optionally via automatic vacuum loader. For materials with low bulk density or irregular particle shape (recycled flake, regrind), a crammer feeder can be mounted on the feed throat to force-feed material into the screw channel and prevent bridging. A water-cooled feed throat jacket keeps the feed zone below 50°C, preventing premature softening that causes feed blockage.
Within the barrel, the rotating screw performs three sequential functions: the feed section conveys solid granules forward; the compression section — where screw channel depth progressively decreases from 8–12 mm to 3–5 mm — compresses and shears the material against the heated barrel wall, transitioning it from solid to melt; the metering section delivers a homogeneous melt at constant pressure (10–25 MPa) to the die head. Screw compression ratio is matched to material: 2.5:1 for PE, 2.8:1 for PP, 3.0:1 for rigid PVC, and 3.5:1 for soft PVC.
Before reaching the die, the melt passes through the screen changer. Screen pack specification depends on product quality requirements: 60 mesh for pipe and thick sheet (removes particles >250 μm), 80 mesh for blown film (>180 μm), and 100 mesh for thin-gauge film and monofilament (>150 μm). A melt pressure transducer before and after the screen pack monitors pressure drop — when differential pressure exceeds 5–7 MPa, it is time to change the screen.
The filtered melt enters the die head — flat sheet die, blown film spiral mandrel die, pipe/tubing crosshead die, profile die, or strand pelletizing die — where it takes its final cross-sectional shape. Downstream equipment (cooling, sizing, haul-off, winding or cutting) completes the line. For turnkey projects, Chenxing supplies the complete line — extruder + die + downstream — as a single integrated package with hot-cold mixing and recycling equipment available as pre-engineered add-ons.
| Product | Typical Material | Recommended Model | Downstream Equipment |
|---|
| HDPE Pipe (16–250 mm) | HDPE PE80/PE100 | SJ-65 to SJ-90 | Pipe die, vacuum tank, haul-off, cutter |
| LDPE/LLDPE Blown Film | LDPE, LLDPE | SJ-50 to SJ-75 | Film die, air ring, bubble cage, winder |
| PVC Pipe (16–200 mm) | PVC-U, PVC-M | SJ-65 to SJ-90 | Pipe die, vacuum tank, haul-off, cutter |
| PP/HDPE Monofilament | PP, HDPE | SJ-65 to SJ-75 | Spinneret die, water bath, stretching unit, winder |
| PE Strapping Tape | HDPE, PP | SJ-65 to SJ-75 | Flat die, water bath, stretching, embossing, winder |
| Cable Insulation (PVC/PE) | PVC, XLPE, HDPE | SJ-50 to SJ-90 | Crosshead die, cooling trough, capstan, coiler |
| Compound Granulation | PE, PP, PVC, Filled Compounds | SJ-90 to SJ-150 | Strand die, water bath, air knife, pelletizer |
| WPC Profile / Decking | PE/Wood Flour, PVC/Wood Flour | SJ-65 to SJ-90 | Profile die, calibration, haul-off, cutter |
Diversifying your product line? Combine the SJ extruder with our plastic rattan extrusion line for synthetic rattan or PET bottle washing line for integrated recycling — maximizing the return on your extrusion investment.
| Your Application | Best SJ Model | SJH Alternative (Higher Output) |
|---|
| Laboratory / R&D / Sampling | SJ-25 or SJ-30 | — |
| Small-batch pipe or profile | SJ-50 (7.5–37 kW) | — |
| Standard pipe, film, or profile production | SJ-65 (22–90 kW) — most popular | SJH-60 (300–400 kg/hr) |
| Higher-volume pipe or blown film | SJ-75 or SJ-90 | SJH-75 (400–500 kg/hr) or SJH-90 (600–800 kg/hr) |
| Large-scale granulation or sheet | SJ-120 or SJ-150 | SJH-90 High-Output (850–1000 kg/hr) |
PE (HDPE, LDPE, LLDPE, MDPE), PP, rigid and plasticized PVC, ABS, PS, EVA, TPE, and filled/recycled compounds. It is not suitable for unplasticized PVC dry-blend powder — for PVC powder direct extrusion, use our SJSZ conical twin screw extruder.
25:1 — general-purpose pipe, profile, and granulation. 33:1 — materials requiring devolatilization (recycled, hygroscopic, filled compounds). 38:1 (SJH) — high-speed film, cable insulation, and masterbatch requiring maximum melt homogeneity at 120–150 rpm. Chenxing engineers will recommend the optimal L/D ratio based on your material and product.
MOQ is 1 complete extruder with screw and barrel configured for your material and output target. Spare screw elements, barrels, heating bands, and gearbox components can be reordered individually with no minimum quantity.
CE certified, manufactured under ISO 9001:2015. Motors are Siemens/ABB IEC-compliant. Electrical cabinet meets IP54. For SASO, SONCAP, UL, or GOST certifications, we supply regionally compliant components during order specification. Full documentation included with shipment.
Standard delivery: 45–60 working days. On-site installation and commissioning: 5–8 working days with Chenxing Machinery engineers. Free remote video guidance is available. A complete extrusion line (extruder + downstream) adds 10–15 working days.
24-month warranty on the gearbox, screw, and barrel mainframe. 12-month warranty on electrical components, heating bands, and temperature controllers. Lifetime free online technical support. Paid on-site service available within 7 working days globally. Spare parts ship within 48 hours.
FOB price depends on model, L/D ratio, screw configuration, motor brand, and optional equipment. Contact our sales team with your material, target output, and product type for a detailed quotation within 24 hours. Every quotation includes a free CAD factory layout drawing.
Yes. The standard flange-mount die connection allows die changeover. You will need the appropriate downstream equipment (film tower vs. pipe tank) and possibly a screw configuration change if the material or output requirements differ significantly. Typical product changeover time is 4–8 hours.
With standard PE/PP processing, the nitride-hardened 38CrMoAlA screw and bimetallic barrel provide 15,000–25,000 operating hours before measurable wear. Processing filled compounds (CaCO₃ >20%) reduces service life to 8,000–15,000 hours. Barrel and screw wear are monitored during annual maintenance inspections — Chenxing provides wear measurement guidelines.
Every SJ extruder undergoes a factory acceptance test: gearbox run under load for 4 hours, all heating zones calibrated, and a production run with your specified material. Test reports document: output rate, melt temperature stability (±3°C), motor load percentage, and melt pressure consistency. Video documentation is included with shipment.
Power: 1.1–355 kW at 380V/50Hz three-phase (60Hz available). Cooling water for feed throat: 0.3–2.0 m³/hr at 15–25°C. Floor space varies by model — from approximately 2 m × 1 m (SJ-25) to 8 m × 3 m (SJ-150). No special foundation required — anti-vibration pads on level concrete are standard.
Yes. Chenxing Machinery supplies turnkey extrusion lines — extruder + die + downstream equipment + hot-cold mixer + recycling system if needed. We provide CAD factory layout, material handling integration, operator training, and remote production support. Tell us your end product and we deliver the complete package.
Chenxing Machinery has designed, manufactured, and exported SJ series extruders to plastic processors in over 30 countries. Our complete extrusion equipment portfolio spans from 5 kg/hr lab extruders to 1000 kg/hr high-speed lines, and our engineering team has configured screws for hundreds of material formulations — standard PE/PP grades, wood-plastic composites, calcium-carbonate-filled compounds, recycled blends, and engineering thermoplastics.
Your SJ extruder runs at full production speed at our Zhangjiagang facility before disassembly. You can attend in person or via live video stream. The factory acceptance test report documents: output rate at multiple screw speeds, melt temperature profile across all zones, motor load, gearbox vibration analysis, and melt pressure stability. The machine is not crated until you sign off — or until we send the full video documentation for your approval.
Beyond the extruder: CAD factory layout, material formulation recommendations with local sourcing options, English SOP manuals, turnkey line installation (extruder + die + downstream as a single package), and 5 working days of on-site operator training. For processors entering a new product category, our application engineers provide process consultation from material selection to final product specification.
Stay updated on extrusion technology, material trends, and equipment maintenance through Chenxing Machinery's news page, covering plastic pipe, film, profile, and recycling developments relevant to global processors.
Ready to invest in a single screw extruder or complete extrusion line? Here is the process:
You send your requirements — material type, target hourly output, desired product (pipe, film, profile, sheet, granulation), and local utility specifications
We deliver a customized proposal within 24 hours — including recommended SJ or SJH model, L/D ratio, screw configuration, downstream equipment package, FOB price, delivery timeline, and CAD factory layout
You review and refine — our engineers adjust the configuration until it matches your exact production goals and budget
We build, test, and ship — with complete video documentation of the factory acceptance test before container loading
Or email directly: ceo@cxsljx.com
Include your material type and target hourly output for the fastest quotation turnaround. All inquiries receive a response within 24 hours.
