Pallet Stretch Wrapping: Technology and Best Practices

Executive summary

Standard perimeter stretch wrapping protects pallet flanks but leaves the top face exposed to overhead moisture, atmospheric particulate fallout, and warehouse dust. The B series automatic turntable stretch wrapping system integrates a dual-column overhead gantry top sheet dispenser directly aligned with the turntable rotation axis. During the automated packaging cycle, the overhead carriage feeds and cuts a flat polyethylene (PE) barrier film over the load crown. Consecutive upper spiral wraps immediately interlock the sheet overhang against the vertical cargo faces, producing a sealed, water-resistant enclosure with zero manual operator intervention.

The machine architecture couples an ultra-rigid structural steel gantry with a heavy-duty turntable foundation. Dual blue structural uprights support the horizontal top-sheet crossbeam, housing linear traverse guides and an automated roll-unwind carriage. Beside the turntable, an independent mast supports the motorized 250% power pre-stretch film carriage, paired with a pneumatic base-level clamp, hot-wire severing unit, and mechanical brush wiper. The standalone PLC control cabinet features a multi-tier visual beacon, coordinating the entire motion sequence to turn palletized unit loads into weather-shielded, shipping-ready freight.

Table of Contents

Why add a top sheet

Axial perimeter wrapping stabilizes vertical stack tiers but leaves the cargo apex open. Pallets held in cross-dock staging, exposed to intermodal sea container condensation (cargo sweat), or stored in high-particulate industrial hubs inevitably accumulate moisture, soot, and contaminants.

An automated top sheet covers the horizontal surface. When the side stretch film overwraps the downward-draped sheet skirts, it locks the outer perimeter under continuous elastic tension, eliminating the need for adhesives or manual taping. Automating this sequence inside the machine envelope removes forklift bottlenecks and eliminates the high-risk task of personnel climbing or leaning over moving loads to drape sheet plastic manually.

Machine sequence

  1. Load Infeed & Axis Centering: A forklift sets the palletized cargo onto the 2,200 mm turntable. Ultrasonic or photo-eye sensors verify cargo profile clearances.
  2. Base Reinforcement Wrap: The turntable accelerates via soft-start variable frequency drive (VFD). The film carriage pre-stretches film to 250% and delivers programmed reinforcement wraps around the bottom pallet deck boards.
  3. Spiral Ascent & Apex Pause: The carriage spirals up to the top cargo edge at controlled vertical carriage speeds. The turntable enters a controlled deceleration ramp and holds stationary under mechanical braking.
  4. Top Sheet Deployment: The overhead gantry clamp drives forward, feeds the targeted PE cover film across the top cargo surface, and cuts the sheet cleanly with an automated pneumatic cutter. The film skirts drape naturally down all four lateral faces.
  5. Overhang Lock & Spiral Descent: The turntable resumes rotation immediately. The film carriage applies reinforcing top wraps directly over the draped film skirts, encapsulating the sheet edges under tension before spiraling down to the pallet base.
  6. Pneumatic Cut & Wipe Cycle: At the conclusion of the final lower wrap, a pneumatic arm grips the stretch film web, a temperature-controlled heating element severs the film, and a compliance brush wipes the tail cleanly onto the pallet skirt. The turntable positions precisely at its calibrated zero-home datum.

The cycle parameters allow full operator flexibility. For total weather resistance, the top sheet deploys before the top wraps. If the process requires basic dust cover protection only, the cycle program can dispense the sheet at ground level prior to rotation.

Machine data

Parameter Specification (B Series / B300)
Rated Throughput 20–30 loads per hour (cycle & wrap-count dependent)
Maximum Load Capacity 1,800 kg (rigid dynamic rating)
Turntable Diameter & Height 2,200 mm diameter; 400 mm low-profile bed height
Turntable Drive & Speed Inverter-controlled 0–12 RPM with programmable ramp-up/down
Primary Stretch Film Spec LLDPE core-wound; 500 mm web width; 25 µm (0.025 mm) thickness; 76 mm core ID
Powered Pre-Stretch Ratio 250% fixed gearing ratio (1 m yields 3.5 m; optional 100%–300%)
Carriage Vertical Speed Inverter motor drive, variable up to 2.9 m/min
Reinforcement Wrapping Cycles 0–99 independent revolutions (bottom, middle, top)
Film Tail Termination Unit Pneumatic clamping jaw, impulse heated wire cut, compliant brush wiper
Main Utility Demands 3-Phase AC 380 V / 50 Hz; compressed clean air 0.6–0.8 MPa (6–8 kgf/cm²)

Top sheet roll dimensions, gantry vertical stroke clearances, and custom carriage pre-stretch gearing can be tailored to non-standard load footprints upon engineering inquiry.

Sizing the top sheet

To guarantee complete weather-resistant water shedding, calculate sheet roll width and draw length using load dimensions plus the drop overhang:

Sheet Width ≥ Load Width + 2 × Skirt Overhang

Sheet Cut Length ≥ Load Length + 2 × Skirt Overhang

Engineering Application: For a standard EUR-2 pallet profile (1,200 mm length × 1,000 mm width) with a specified 150 mm perimeter skirt drape:

  • Target Sheet Width = 1,000 mm + (2 × 150 mm) = 1,300 mm
  • Target Sheet Cut Length = 1,200 mm + (2 × 150 mm) = 1,500 mm

The resulting 150 mm lateral skirt hangs over the edges of the load. Because the primary stretch film web is 500 mm wide, three overlapping top reinforcement wraps cover a vertical profile well in excess of 200 mm. This completely seals the 150 mm overhang against the cargo, preventing wind separation during open-bed transit.

Always cross-reference the load footprint against the turntable boundary:

Diagonal Clearance = √(Length² + Width²)

For a 1,200 × 1,000 mm load:

Diagonal = √(1,200² + 1,000²) = √(1,440,000 + 1,000,000) ≈ 1,562 mm

The 1,562 mm rotational sweep diameter operates safely inside the 2,200 mm turntable footprint, leaving over 310 mm of radial margin for corner overhang and safety clearances.

Film per load

Stretch film consumption depends on cargo perimeter, target layer overlaps, and powered pre-stretch elongation:

Unstretched Film Length ≈ (Total Wrap Revolutions × Load Perimeter) ÷ (1 + Pre-Stretch Ratio)

Engineering Estimate: A standard 1,200 × 1,000 mm unit load has a horizontal perimeter of:

Perimeter = 2 × (1,200 mm + 1,000 mm) = 4.4 m

Applying a 20-revolution total wrapping schedule (3 base, 2 upward spiral, 3 top, 2 downward spiral, plus reinforcement bands) requires 88 m of elongated film on the pallet:

Film Applied = 20 × 4.4 m = 88 m

With the powered carriage set at 250% pre-stretch (elongation multiplier = 1 + 2.50 = 3.5):

Supply Film Drawn = 88 m ÷ 3.5 ≈ 25.1 m

Factoring in the 1.5 m top sheet cover, total single-pallet packaging material consumption is approximately 25.1 m of stretch film web plus 1.5 m of PE top sheet.

Selection checklist

  1. Load Boundary Envelope: Document minimum/maximum cargo length, width, stacked height, and gross pallet weight.
  2. Line Throughput Demand: Specify pallets per hour to balance gantry traverse speeds against wrap schedules.
  3. Environmental Exposure: Determine indoor dry storage, humid sea container transit, or open yard exposure to select top sheet thickness (typically 30–60 µm).
  4. Program Flexibility: Establish whether top-sheet weatherproofing applies to 100% of production or runs intermittently via recipe selection.
  5. Feed Interface: Identify whether the unit will be loaded as a standalone machine by counterbalance forklift or integrated into future powered roller conveyor sections.

Safety

The machine complies with European machinery directive requirements under EN 415-6 (Safety of Packaging Machines: Pallet Wrapping Machines), with comprehensive risk analysis structured under EN ISO 12100:2010. All electrical control gear, ground paths, and circuit isolation devices satisfy EN 60204-1.

Standard plant floor protection includes:

  • IP54 sealed industrial enclosure with lockable main power disconnect switch.
  • Panel-mounted and remote emergency mushroom stop pushbuttons (E-stops).
  • Controlled acceleration/deceleration profiles to prevent top-tier carton shifting.
  • Precision home-position docking sensors to ensure the turntable always returns to a fixed fork-truck loading plane.

Engineering FAQ

Q: Can the top sheet dispenser be deactivated for domestic indoor-only pallets? A: Yes. The PLC interface stores individual wrapping recipes. Operators can bypass the overhead dispenser and run conventional perimeter-only wrapping cycles with a single recipe selection on the HMI.

Q: What prevents the loose top sheet from blowing off before the outer wrap locks it down? A: The turntable stops rotating before the sheet is placed. The gantry lowers the sheet flat onto the load crown. The film carriage then immediately applies the top wrap layers around the overhang, securing the cover before the machine accelerates up to speed.

Q: Can this semi-automatic system integrate with automated conveyors in the future? A: Yes. The B series turntable structural frame can be retrofitted with motor-driven chain or roller conveyors, paired with safety light curtains and handshaking interlocks for fully automated packaging lines.

Next step

  1. Send your pallet specifications: Email load dimensions (L × W × H), gross weights, and line output targets (loads/hour) to info@fhopepack.com.
  2. Engineering Review: Our mechanical design team calculates clearance sweeps, selects optimal turntable diameters, and configures gantry stroke envelopes.
  3. Detailed Proposal: Receive an itemized technical proposal, functional layout CAD drawings, and fixed commercial quotation within 24 hours.

Sources

  • FHOPE Technical Documentation: B300 Series Automatic Pallet Packaging Systems
  • EN 415-6: Safety of packaging machines – Part 6: Pallet wrapping machines
  • EN ISO 12100:2010: Safety of machinery – General principles for design – Risk assessment and risk reduction
  • EN 60204-1: Safety of machinery – Electrical equipment of machines – Part 1: General requirements

Last reviewed: 2026-10-20

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