Rack Protector Profile Extrusion Line

Product Overview

The Rack Protector Profile Extrusion Line is a complete turnkey production system engineered for continuous manufacturing of U-shaped HDPE and PP racking column protectors — the essential safety barrier deployed across warehouse racking, distribution centers, cold storage facilities, and industrial plants worldwide.

At the core of the line is the SJ-65/33 single screw extruder featuring a 33:1 L/D ratio that delivers optimal plasticization of HDPE extrusion-grade material at 60–200 kg/h. The custom U-profile extrusion die produces reinforced internal rib structures for superior impact resistance. Combined with a vacuum calibration table, dual caterpillar haul-off, and PLC-controlled cutting unit, this line ensures dimensional accuracy of ±0.3 mm and surface finish consistency from the first piece to the ten-thousandth.

Quick Specs

Technical Parameters

Extruder Model Comparison

Model Selection Guide

Output Conversion Table

Note: Actual output varies with profile cross-section geometry and cooling time requirements. Our engineering team provides a customized throughput simulation based on your target product dimensions.

Rack Protector Product Specifications

System Configuration — 10 Stations in Detail

Station 1: High-Speed Mixer (SHR-100A)

The high-speed mixer blends virgin HDPE pellets with masterbatch colorant, UV stabilizers, and optionally up to 30% post-consumer recycled (PCR) flake. The SHR-100A features a 100L mixing chamber with a dual-speed motor (14/22 kW) operating at 600–800 rpm. Frictional heat generation raises material temperature to 80–110°C within 8–12 minutes, pre-drying the blend and driving off surface moisture — critical for HDPE which can exhibit hydrolysis defects if moisture exceeds 0.05% at the extruder throat.

• Chamber volume: 100 L

• Motor: 14/22 kW (low/high speed)

• Rotor speed: 600–800 rpm

• Batch cycle: 8–12 minutes

• Discharge: Pneumatic gate valve, full discharge under 30 seconds

• Material: SUS304 stainless steel contact surfaces

Station 2: Vacuum Hopper Loader (CX-180)

The vacuum hopper loader transports mixed material from the SHR-100A discharge port to the extruder feed hopper via negative-pressure pneumatic conveying. The CX-180 unit generates -0.5 bar vacuum through a side-channel blower, lifting HDPE compound at 0.05 T/h with a conveying height up to 4 meters. A capacitive level sensor at the extruder hopper triggers automatic refill cycles, preventing material starvation that can cause output fluctuation and melt pressure instability at the die.

• Conveying capacity: 0.05 T/h

• Vacuum blower: 1.1 kW side-channel

• Max conveying height: 4 m

• Hopper volume: 12 L

• Level sensor: Capacitive proximity, auto stop/start

• Filter: Cartridge filter with pulse-jet cleaning

Station 3: SJ-65/33 Single Screw Extruder (Core Unit)

The SJ-65/33 single screw extruder is the heart of the line, purpose-optimized for HDPE processing. Its 33:1 L/D ratio — longer than the typical 28:1–30:1 found on general-purpose extruders — provides extended residence time for complete melting and homogenization of semi-crystalline HDPE (melting point 130–137°C). The single-stage barrier screw separates the solid bed from the melt pool through a secondary flight channel, increasing melting efficiency by 25–30% compared to conventional metering screws. The barrel is constructed from 38CrMoAlA alloy steel with nitrided inner surface (hardness HV 900–1000), and the screw flight tips receive bimetallic hard-facing (CoCr-W alloy) for abrasion resistance when processing recycled-content compounds.

Temperature Profile (HDPE Processing):

• Screw diameter: Φ65 mm

• L/D ratio: 33:1

• Compression ratio: 2.8:1

• Screw material: 38CrMoAlA, nitrided + bimetallic flight tips

• Barrel: 38CrMoAlA, nitrided ID, bimetal liner at feed zone

• Drive: 22–37 kW Siemens VFD motor, gearbox with hardened helical gears

• Heating: 5-zone ceramic band heater, 18 kW total

• Cooling: 4 forced-air barrel cooling fans

• Max screw speed: 90 rpm

• Output (HDPE pellet): 60–200 kg/h

• Screen changer: Manual slide-plate type, 80/120 mesh

Station 4: Oil Mold Temperature Controller (BSR-12)

The oil mold temperature controller circulates high-temperature thermal oil (up to 350°C) through the extrusion die head's internal heating channels. Unlike water-based mold temperature controllers that are limited to 180°C at atmospheric pressure, the oil system maintains precise die temperature at 200–230°C for HDPE profile extrusion — critical because die temperature deviation exceeding ±2°C causes localized viscosity variation and results in uneven wall thickness distribution across the U-shaped cross-section. The BSR-12 uses a PID microprocessor controller (Omron or equivalent) with ±1°C steady-state accuracy.

• Max temperature: 350°C

• Heating power: 12 kW

• Pump: 0.75 kW, 50 L/min

• Control accuracy: PID ±1°C

• Tank capacity: 24 L

• Medium: Synthetic thermal oil (flash point >300°C)

• Safety: Over-temperature cutoff, low-oil-level alarm, pressure relief valve

Station 5: Vacuum Calibration Table (YF-240 Custom)

The vacuum calibration table is the most dimension-critical station in the entire line. The YF-240 is custom-sized for rack protector profiles up to 240 mm wide, housing 3–4 precision-machined calibration blocks (aluminum or brass) arranged sequentially. Each block contains a negative cavity matching the target U-profile cross-section, with 0.5 mm diameter vacuum slots machined along the cavity surface. A water-ring vacuum pump generates -0.06 to -0.08 MPa vacuum, drawing the hot extrudate against the cooled cavity walls for simultaneous shaping and quenching. Spray bars between blocks provide supplementary water cooling at 15–20°C (supplied by Station 6 chiller). The entire table is mounted on linear guide rails with handwheel-driven transverse and vertical adjustment for precise die-to-calibrator alignment.

• Max profile width: 240 mm

• Calibration blocks: 3–4 precision aluminum/brass blocks

• Vacuum pump: Water-ring type, 2.2 kW, -0.06 to -0.08 MPa

• Spray cooling: Multi-nozzle spray bars, 15–20°C water

• Tank capacity: 600 L (stainless steel)

• Adjustment: Linear guide rails, handwheel X-Y-Z

• Length: 4,000 mm

• Water circulation: Pump-driven recirculation to chiller

Station 6: Air-Cooled Chiller (CXL-5F)

The air-cooled chiller supplies temperature-controlled chilled water (3–35°C) to both the vacuum calibration table spray system and the extruder feed throat cooling jacket. For HDPE rack protector production, the cooling water is typically maintained at 15–18°C: lower than 12°C risks thermal shock that can introduce residual stress and cause post-molding warpage of the U-profile; higher than 22°C extends the cooling length required and limits line speed. The CXL-5F uses a scroll compressor with R410A refrigerant, delivering 11,000 Kcal/h cooling capacity at 5 HP input.

• Compressor: 5 HP scroll, R410A

• Cooling capacity: 11,000 Kcal/h (12.8 kW)

• Temperature range: 3–35°C

• Temperature accuracy: ±1°C

• Water tank: 120 L (SUS304)

• Water pump: 0.75 kW, 80 L/min, 25 m head

• Condenser: Fin-and-tube, axial fan

• Control: Microprocessor PID, auto compressor cycling

Station 7: Dual Caterpillar Haul-Off

The dual caterpillar haul-off provides consistent pulling force to draw the solidified profile through the calibration and cooling stages at a precisely controlled speed. Two opposing caterpillar tracks with custom-molded rubber pads grip the U-profile on both sides without surface marring. The pads are profiled to match the U-shape side walls, distributing contact pressure across 60% of the profile surface area to prevent localized deformation. A 2.2 kW VFD-controlled AC motor drives both tracks synchronously through a common gearbox, with speed adjustable from 0.5 to 6 m/min. This speed range corresponds to a production cycle of 30–120 seconds per 600 mm piece.

• Track type: Dual caterpillar, synchronized drive

• Speed range: 0.5–6 m/min (VFD)

• Motor: 2.2 kW AC, Siemens VFD

• Pad material: Custom-molded rubber (Shore A 65–70)

• Contact length: 1,200 mm per track

• Clamping: Pneumatic cylinder, adjustable pressure 0.2–0.6 MPa

• Frame: Welded steel, height-adjustable pedestal

Station 8: Lifting-Blade Cutter

The lifting-blade cutter performs clean, burr-free cross-cuts on the continuously moving U-profile. It uses a lifting-blade mechanism: the Φ400 mm carbide-tipped saw blade remains retracted below the profile line during extrusion, then rises rapidly (pneumatic cylinder actuation) to cut through the profile in under 1.5 seconds during a synchronized dwell period. A PLC controller (Siemens S7-200 or equivalent) coordinates the cut trigger with an encoder on the haul-off drive, achieving length accuracy of ±1.0 mm for pieces between 300–800 mm. A dust collection shroud with a 0.75 kW exhaust fan captures HDPE cutting chips for in-house recycling.

• Blade diameter: Φ400 mm, carbide-tipped

• Motor: 2.2–3.0 kW, 2,800 rpm

• Cut cycle time: <1.5 seconds

• Length control: PLC + encoder, ±1.0 mm

• Length range: 300–800 mm (standard), up to 1,200 mm (extended)

• Actuation: Pneumatic lift cylinder, 0.4–0.6 MPa

• Dust collection: Integrated shroud + exhaust fan 0.75 kW

• Safety: Blade guard, emergency stop, two-hand anti-tie-down (optional)

Station 9: Pneumatic Stacker

The pneumatic stacker receives cut pieces from the discharge conveyor and organizes them into neat stacks for manual bundling and palletizing. A pneumatic tilting mechanism tips each arriving piece onto an accumulation table at a 15° incline, where gravity aligns the pieces against a backstop. Once a pre-set count (typically 20–50 pieces) is reached, an audible signal prompts the operator to remove the stack and restart the counter. The design is deliberately simple — no robotic gantry or complex automation — to keep capital cost low and maintenance accessible for operators in developing markets.

• Operation: Pneumatic tilting, manual offloading

• Tilt angle: 15°

• Accumulation capacity: 50 pieces (adjustable counter)

• Air supply: 0.4–0.6 MPa

• Frame: Welded steel, powder-coated

• Controls: Pneumatic solenoid valve, piece counter with LED display

Station 10: Ink Transfer Printer (Optional)

The ink transfer printer applies permanent surface markings — production date, batch number, specifications, or customer logo — on the outer face of each rack protector as it passes through the haul-off. The contact ink-transfer method uses a silicone roller that picks up heated ink from an engraved plate and transfers it onto the HDPE surface. Marking is continuous and synchronized with line speed, adding zero cycle time. This station is optional but strongly recommended for customers supplying government tenders or large retail chains that require traceability markings.

• Printing method: Contact ink transfer (silicone roller)

• Marking speed: Synchronized with line speed, 0.5–6 m/min

• Ink type: Fast-dry solvent-based, HDPE-compatible

• Marking content: Alphanumeric, logos, batch codes

• Power: 0.2 kW

Core Features

1. Closed-Loop Recycling — 30–40% Raw Material Cost Reduction

Chenxing is one of the few manufacturers worldwide that builds both plastic recycling granulating lines and profile extrusion lines under one roof. This unique vertical integration allows customers to deploy a closed-loop manufacturing model: post-industrial HDPE scrap (offcuts, rejected pieces, sprue from cutting station) is fed into Chenxing's CXJ120 recycling granulator at 260–500 kg/h, pelletized, and reintroduced as feedstock to the rack protector extruder at up to 30% blend ratio with virgin resin. At prevailing Southeast Asian HDPE virgin pellet prices of 285–330 per metric ton — translating to 120,000 annual savings for a single-shift operation producing 15,000 pieces per day.

2. One Line, Multiple Products — Quick Die Changeover

The modular die head and calibration system enables a single extrusion line to produce U-shaped rack protectors, L-shaped corner guards, C-channel edge protectors, and flat wall bumpers by swapping the die head and calibration blocks. A trained operator completes a full die changeover in 45–60 minutes. For factories serving diverse warehouse safety markets, this means one capital investment covers three or more product SKUs — dramatically improving equipment utilization rate from a typical 55% (single-product line) to over 80%.

3. SJ-65/33 — An Extruder Engineered Specifically for HDPE

Unlike generic single-screw extruders that compromise between PVC, PP, and PE processing, the SJ-65/33 is designed around HDPE's specific rheological behavior. The 33:1 L/D provides the extended residence time required for melting HDPE's semi-crystalline structure (crystallinity 60–80%). The barrier screw design prevents un-melted pellet breakthrough at high throughput — a common failure mode in shorter 25:1–28:1 extruders running HDPE above 150 kg/h. Siemens VFD drive with 22–37 kW motor delivers constant torque across 10–90 rpm, maintaining melt pressure stability of ±2 bar at the die entry.

4. Precision Calibration — ±0.3 mm Wall Thickness Tolerance

The YF-240 vacuum calibration system achieves ±0.3 mm dimensional accuracy on wall thickness through three engineering measures: (a) multi-stage calibration blocks with progressively tighter tolerances (first block: +0.5 mm oversized for bulk shaping; last block: +0.1 mm for final sizing); (b) independent vacuum circuits per block (Z1: -0.04 MPa for gentle initial contact, Z2–Z3: -0.07 MPa for full conformal cooling); (c) temperature-controlled spray water at 15–18°C from the CXL-5F chiller, preventing thermal shock warpage that typically introduces 0.5–0.8 mm deviation in conventional open-tank cooling systems.

5. Modular Scalability — Grow from 120 to 250 pcs/h

All extrusion downstream equipment is sized for the SJ-75 upgrade path. The YF-240 calibration table accommodates up to 350 kg/h throughput, the dual caterpillar haul-off handles 0.5–6 m/min line speeds, and the lifting-blade cutter cycles at up to 4 cuts per minute. A customer starting with the SJ-65/33 at 120 pcs/h can upgrade to the SJ-75/33 extruder at 250 pcs/h without replacing any downstream equipment — only the extruder, die head, and upstream feeding system require change. This saves approximately 40% of total line cost compared to purchasing a second complete line.

6. CE Certified with Southeast Asian Local Support

Every turnkey extrusion line ships with CE marking documentation, including machinery directive 2006/42/EC compliance, electrical safety (EN 60204-1), and EMC conformity. Chenxing maintains local-language service offices in Thailand (Bangkok), Vietnam (Ho Chi Minh City), and Malaysia (Kuala Lumpur), providing on-site installation, commissioning, and after-sales support within 48-hour response time across ASEAN markets. This localized presence is a critical differentiator for customers in emerging markets where European and Chinese competitors typically rely on fly-in technicians with 1–2 week lead times.

7. ISO9001 Factory with Full Traceability

Manufacturing takes place at Chenxing's 12,000 m² facility in Zhangjiagang, Jiangsu, under ISO9001:2015 quality management. Critical components — gearbox, screw, barrel, calibration blocks — receive individual inspection reports with CMM dimensional verification. Every extruder undergoes a 4-hour dry run test and a 2-hour material trial (HDPE pellet) before crating. Full documentation package includes: GA drawing, electrical schematic, PLC program backup, spare parts catalog, and maintenance manual in English.

Production Process

Process Engineering Notes

Formulation Optimization: For outdoor applications requiring UV12 rating, HALS (hindered amine light stabilizer) at 0.3–0.5% loading combined with carbon black at 2.0–2.5% achieves >5-year color retention in tropical climates (Malaysia, Indonesia, Middle East). For cold storage applications (-30°C environments), a PP copolymer component at 10–15% blend improves low-temperature impact from 4 kJ/m² to 8 kJ/m² (Charpy notched, ISO 179).

Screw RPM vs. Output Relationship: At 60 rpm, the SJ-65/33 delivers approximately 120 kg/h with HDPE (MFI 0.5). Pushing to 90 rpm raises output to 200 kg/h. However, screw speeds above 75 rpm can introduce melt fracture when running high-viscosity recycled-content blends above 30% PCR. Our recommended operating window for consistent surface finish: 55–75 rpm for virgin HDPE, 45–60 rpm for 30% PCR blends.

Frequently Asked Questions

Q1: What distinguishes Chenxing's SJ-65/33 from a generic 65 mm single screw extruder for HDPE rack protector production?

The SJ-65/33's 33:1 L/D ratio — versus the industry-common 28:1–30:1 — provides approximately 15–20% additional residence time in the melting and metering zones. For semi-crystalline HDPE (crystallinity 60–80%, melting range 130–137°C), this extra barrel length delivers two measurable advantages: first, un-melted pellet count at the screen pack drops from 3–5% (typical for L/D=28 extruders at 150 kg/h) to below 0.5%; second, melt temperature uniformity improves from ±4°C to ±1.5°C across the die entry cross-section, as validated by our in-house IR thermography during factory acceptance tests. Additionally, the barrier screw design physically separates the solid bed from the melt pool with a secondary flight channel 0.8–1.2 mm shallower than the primary channel, increasing conductive melting surface area by approximately 35% compared to a conventional three-zone metering screw — critical for maintaining throughput stability when processing recycled-content blends where pellet bulk density can vary ±8% batch to batch.

Q2: What is the actual production economics — including energy, labor, and consumables — for operating this line at 120 pcs/h?

At 120 pcs/h output (600 mm standard guard, 1.0 kg/piece), operating 20 days/month in two 8-hour shifts, monthly production reaches approximately 38,400 pieces. Operating cost breakdown per piece: HDPE resin (virgin, 1.05; masterbatch colorant (2% loading, yellow, 0.076; electricity (total line load ~65 kW average, 0.043; labor (2 operators/shift × 2 shifts, 0.042; die and cutter blade consumables amortized = 1.23. At a typical Southeast Asian wholesale price of 2.80/piece for 600 mm HDPE rack protectors, gross margin per piece is 1.57. A single-shift operation recovers equipment investment (approximately 85,000 FOB for the complete line) within 8–12 months based on this margin structure. Integrating a plastic recycling granulator to substitute 30% recycled content pushes per-piece material cost down to 0.31/piece and shortening payback to 6–8 months.

Q3: How does the vacuum calibration system maintain ±0.3 mm tolerance on the internal rib geometry — the most dimensionally challenging feature of U-shaped rack protectors?

The internal reinforcing ribs of a U-shaped rack protector (typically 2–3 vertical ribs, 2–3 mm thick, spanning the internal width of 80–160 mm) present a calibration challenge because they are shielded from direct spray water contact and rely almost entirely on conductive heat transfer through the calibration block. Our YF-240 system addresses this with three engineering measures: (a) the calibration block cavity includes dedicated vacuum slots machined at 15° offset angles on both faces of each rib cavity, applying -0.06 MPa vacuum to pull the soft extrudate into full rib form before the HDPE skin freezes (skin solidification occurs at approximately 115°C, within the first 18–22 mm of calibration block contact at 1.5 m/min line speed); (b) copper thermal pins (Φ3 mm, 6 pins per rib cavity) are press-fitted into the aluminum calibration block to create high-conductivity heat extraction paths — copper's thermal conductivity (398 W/m·K vs. aluminum 205 W/m·K) nearly doubles the local cooling rate at rib root positions; (c) the third calibration block is machined to final dimensions with no oversize allowance (unlike blocks 1 and 2 which have +0.5 mm and +0.2 mm clearance), performing a final sizing pass that corrects any rib thickness drift accumulated through earlier stages. This three-block progressive calibration strategy achieves rib thickness variation <0.15 mm across a 160 mm wide guard — validated by CMM inspection on 50-piece production samples during factory commissioning.

Q4: Can the line process flame-retardant HDPE compounds for rack protectors used in petrochemical and mining facilities?

Yes, with specific hardware adaptations. UL94 V-0 or V-2 flame-retardant HDPE compounds typically contain 15–25% loading of halogenated flame retardants (brominated FR + antimony trioxide synergist) or intumescent systems (ammonium polyphosphate + pentaerythritol). Processing these compounds requires: (a) barrel and screw constructed from nitrided steel with bimetallic hard-facing on all flight surfaces — halogenated FRs release corrosive HBr gas at processing temperatures above 220°C, and standard nitrided surfaces (HV 900–1000) can exhibit pitting corrosion within 500–800 operating hours without bimetallic protection; (b) barrel temperature profile reduced by 10–15°C across all zones (feed zone 160–170°C, metering zone 190–200°C) to stay below the FR decomposition threshold while maintaining melt flow; (c) the vacuum calibration tank water requires pH monitoring and neutralization — we recommend a closed-loop chiller circuit with in-line pH sensor and automated sodium bicarbonate dosing to maintain pH 7.0–8.0, preventing acidic water from etching calibration block surfaces. We have delivered FR-HDPE rack protector lines to two Middle Eastern petrochemical warehouse projects requiring ASTM E84 Class A flame spread ratings. The configuration adds approximately 18,000 to the base line price for the full corrosion-protection package.

Q5: What is the actual installation-to-production timeline, and what support does Chenxing provide during the first month of operation?

The standard deployment timeline for a complete rack protector extrusion line: (week 1) two Chenxing commissioning engineers arrive on-site, perform mechanical assembly alignment (3 days) and electrical connection verification (2 days); (week 2) dry-run testing of all stations — extruder screw rotation, haul-off tracking, cutter cycle, vacuum pump — followed by cold commissioning with water only through the calibration system; (week 3) hot commissioning with HDPE material, starting at 30 rpm / 50 kg/h and ramping to target throughput over 3 days while tuning temperature profiles, vacuum levels, and haul-off speed; day 18–20: production of first 500 acceptable pieces with operators under supervision. One engineer remains on-site for an additional 7 days (week 4) to train the full operator team (typically 3–4 operators + 1 supervisor) on daily startup/shutdown procedures, die changeover sequences, troubleshooting common defects (surface sharkskin, wall thickness drift, rib deformation), and preventive maintenance scheduling. After departure, customers receive: a WhatsApp group with the commissioning engineer for real-time troubleshooting (typical response <4 hours during China business hours), remote desktop access capability for PLC diagnostics, and a 12-month warranty on all mechanical and electrical components with spare parts shipped within 48 hours via DHL. Our Southeast Asian offices in Thailand and Vietnam can dispatch a local technician within 48 hours for issues that cannot be resolved remotely — a service level that European extruder manufacturers cannot match in ASEAN markets.

Why Choose Chenxing

Complete Product Matrix

Certifications & Quality

• CE Machinery Directive 2006/42/EC

• ISO9001:2015 Quality Management System

• GRS (Global Recycled Standard) available for recycled-content products

• 4-hour dry-run + 2-hour material trial per extruder before shipment

• CMM dimensional reports for all calibration tooling

Installation & Commissioning

• 2 engineers on-site for 14–21 days

• Operator training in English, Thai, Vietnamese, or Bahasa

• Full documentation package: GA drawings, electrical schematics, PLC backup, spare parts catalog

• Remote PLC diagnostics via TeamViewer / VPN

Warranty & Spare Parts

• 12-month comprehensive warranty (mechanical and electrical)

• Spare parts kit included with every shipment (heaters, thermocouples, seals, belts, filters)

• 48-hour DHL/FedEx express spare parts dispatch

• Lifetime technical support via WhatsApp, WeChat, email, and video call

Proven Deployments

Our rack protector extrusion lines are operating in:

• Thailand — 2 lines producing 80,000 pcs/month for a major 3PL warehouse supplier

• Vietnam — 1 line integrated with in-house recycling for a cold chain logistics operator

• Nigeria — 1 SJ-75/33 line producing heavy-duty guards for port terminal racking

• Saudi Arabia — 1 FR-HDPE line for petrochemical warehouse column protection

• Indonesia — 1 line serving e-commerce fulfillment center racking projects

4-Step Inquiry Process

Step 1: Send Your Requirements
Email ceo@cxsljx.com with your target output (pieces/day or kg/h), desired product dimensions (length × internal width × wall thickness), material preference (virgin HDPE, PP, or recycled blend), and any special requirements (UV rating, flame retardancy, color).

Step 2: Receive Custom Proposal
Within 24 hours (business days), our engineering team responds with a tailored line configuration, GA layout drawing, detailed quotation (FOB Shanghai/Ningbo), and estimated shipping cost to your nearest port.

Step 3: Review & Confirm
We arrange a video call to walk through the technical proposal, discuss any adjustments, and share references from similar installations in your region. Factory visits to our Zhangjiagang facility are welcome.

Step 4: Production & Delivery
After order confirmation (30% T/T deposit), production begins. Standard lead time: 45–60 days. We provide weekly progress updates with photos. Balance payment before shipment. Commissioning engineers are scheduled based on container ETA.

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