Steel wire wrap machine and packaging machine: complete guide

Executive Summary

Unprotected steel wire and slit strip coils are highly susceptible to interstitial condensation, oxidation, and transit-induced spring-back when shipped in intermodal containers. This technical guide outlines the operational kinematics, engineering specifications, and corrosion-prevention strategies for through-the-eye orbital stretch wrapping systems (FPW-300 and FPS-400 series). Topics include mechanical material tensioning, film/VCI paper selection, exact outer-diameter overlap calculation models, and rigorous pre-commissioning protocols compliant with EN ISO 12100 and EN 415-10 industrial packaging safety standards.

Table of Contents

How the Orbital Coil Wrapping Machine Works

Through-the-eye orbital wrapping applies continuous, radial hoop stress across all six external boundaries of a toroidal coil. This method prevents wire coil “pancake” loosening, outer-layer birdcaging, and moisture penetration during ocean freight.

       [ Rotating Orbital Ring ]
             /     |     \
            v      |      v
     +-------------+-------------+
     |   Stretch Film Carriage   |
     +-------------+-------------+
                   |
           (Through-the-Eye)
                   |
                   v
          .-----------------.
         /     COIL EYE      \
        |   (Internal Dia.)   |
        |        (ID)         |
         \                   /
          '-----------------'
                   |
     +-------------+-------------+
     | Polyurethane Drive Roller |
     +---------------------------+
                   ^
                   |  (Coil Rotation)
  1. Coil Infeed & Positioning: The wire or strip coil is transferred via crane C-hook, walking beam, or ramp down-ender onto twin polyurethane-coated drive rollers. The coil sits upright (eye horizontal, axis parallel to the plant floor), aligned directly with the orbital ring’s split-gate centerline.
  2. Shuttle Ring Engagement: The orbital ring segment locks closed through the coil eye via pneumatic mechanical indexers, creating a 360° closed guide path supported by high-molecular-weight polymer rollers.
  3. Synchronized Through-the-Eye Wrapping: Dual variable-frequency drives (VFD) run the orbital ring and support rollers simultaneously. The film carriage orbits through the core aperture while the coil rotates slowly on its base. A mechanical friction brake maintains film tension (between 15 N and 45 N) to secure coil edges without snapping the film.
  4. Overlap Completion & Cutoff: Once the coil completes 360° of rotation plus a programmed tail overlap (typically 200–300 mm past the starting point), the ring parks at its designated home position. The film tail is severed cleanly via an integrated pneumatic hot-knife or guillotine blade, then wiped flat against the coil surface.
  5. Discharge: The motorized cradle indexes outward, and the packed unit is discharged to downstream strapping, timber-skid stacking, or automated weighing stations.

Technical Specifications: FPW-300 vs. FPS-400

The FPW-300 and FPS-300 share identical drive kinetics and ring structures, calibrated respectively for loose-coiled wire products or narrow slit steel coils. The FPS-400 features a reinforced structural chassis, an expanded ring clearance envelope, and higher-torque worm-gear drives designed for heavy-gauge slit coils and wider package widths.

Technical Parameter FPW-300 (Standard Wire / Strip) FPS-400 (Heavy Industrial / Wide Strip)
Coil Inner Diameter (ID) 508 – 610 mm 508 mm / 610 mm (Custom min. 450 mm)
Coil Outer Diameter (OD) 600 – 1,200 mm 800 – 1,400 mm
Coil Width / Axial Length (W) 100 – 300 mm 100 – 400 mm (Optional up to 500 mm)
Maximum Load Capacity 1,000 kg 2,000 kg
Ring Rotation Speed 20 – 80 RPM (VFD-regulated) 20 – 65 RPM (VFD-regulated)
Roller Rotation Speed 1.5 – 3.5 m/min peripheral 1.0 – 3.0 m/min peripheral
Main Drive Power Rating 1.5 kW (Ring) + 0.75 kW (Roller) 4.0 kW (Ring) + 1.5 kW (Roller)
Pneumatic Operating Pressure 0.5 – 0.7 MPa (5 – 7 bar) 0.5 – 0.7 MPa (5 – 7 bar)
Target Packaging Overlap 20% – 80% (HMI Programmable) 10% – 90% (HMI Programmable)
Dual-Material Simultaneous Dispense Optional External Crepe Bracket Integrated Dual-Carriage (Film + Paper)

Protective Wrap Material Selection Guide

Selecting wrap materials involves matching the consumable to transit duration, dew-point shifts, and handling stress:

[ Inner Protective Layer ]  ---> VCI Paper / Film (Passivates bare metal)
             +
[ Core Structural Layer ]   ---> High-Density PE Woven Tape (Resists edge cut)
             +
[ Outer Weather Barrier ]   ---> Cast LLDPE Stretch Film (Seals out moisture)
  • Cast LLDPE Stretch Film (20–35 µm): Primary moisture, dust, and water barrier. Applied with 150%–250% pre-stretch to generate continuous compressive hoop force. Note: Using stretch film alone on non-oiled bright steel risks trapping internal moisture during container condensation (“cargo sweat”).
  • Crepe Kraft Paper (80–120 GSM): Functions as a breathable inner cushion and oil-retention layer. Its high tear resistance prevents sharp slit edges or stiff wire ends from piercing the outer waterproof skin.
  • High-Density Polyethylene (HDPE) / PP Woven Tape: Heavy-duty outer barrier against fork-pocket puncture and transport abrasion. Essential for heavy export coils subject to multiple transshipments.
  • VCI (Vapor Corrosion Inhibitor) Composite Film: Emits volatile polarity-inhibiting chemical vapors that form an invisible passivating molecular barrier on steel surfaces.
  • Dual-Layer Simultaneous Wrapping: Available on the FPS-400 carriage. The machine lays an inner layer of anti-corrosion VCI crepe paper and an outer layer of waterproof stretch film in a single cycle, cutting total cycle time by 45%.

Process Note: Coils must be dry and clean before entering the wrapping cycle. Sealing a coil below ambient dew point traps moisture, causing rapid internal surface oxidation regardless of wrapping thickness.

Kinematic Overlap and Cycle Time Calculation

To guarantee full packaging integrity without film waste, program the rotation ratios between the orbital ring and the support rollers based on the Coil Outer Diameter (OD).

       Film Roll Width (W_f)
       |<----------------->|
       +-------------------+
       |   Overlap Layer   |
       |===== (O_L) =====|
       +-------------------+
             |<- L_adv ->|
         Effective Advance per Pass

1. Peripheral Advance per Pass

The axial movement along the outer circumference per ring rotation is determined by the material roll width and desired overlap fraction:

L_adv = W_f × (1 - O_L)

Where:

  • L_adv = Peripheral advance distance at coil OD (mm)
  • W_f = Material roll width (typically 90 mm, 150 mm, or 250 mm)
  • O_L = Targeted overlap ratio at OD (e.g., 50% = 0.50)

2. Total Ring Passes per Cycle

The number of orbital ring rotations required for one complete 360° coil revolution is:

N_passes = (π × OD) ÷ L_adv

Note on Aperture Geometry: Because the inner diameter (ID) is smaller than the outer diameter (ID < OD), the overlap ratio inside the coil core is significantly denser than on the outer perimeter:

O_L(ID) = 1 - [(OD ÷ ID) × (1 - O_L(OD))]

Engineering Check: Ensure O_L(ID) does not exceed 85–90%. Excessive overlap in the coil core can crowd the center hole and cause the film shuttle to bind during rotation.

3. Pure Packaging Cycle Time

Cycle time in seconds (excluding loading, indexing, and cutoff operations) is calculated as:

T_wrap = (N_passes ÷ ω_ring) × 60

Where ω_ring is the orbital ring speed in RPM.

Engineering Application Example:

  • Coil Specs: OD = 1,000 mm, ID = 508 mm, Width = 200 mm
  • Packaging Film: Width W_f = 100 mm, Overlap target O_L = 50% (0.50)
  • Ring Speed: ω_ring = 60 RPM
  • L_adv = 100 × (1 - 0.50) = 50 mm
  • N_passes = (3.1416 × 1000) ÷ 50 ≈ 62.8 passes (round up to 63 passes)
  • T_wrap = (63 ÷ 60) × 60 = 63 seconds

Adding 15 seconds for automated coil entry, clamping, pneumatic cutting, and ejection yields a total tact time of 78 seconds per coil (~46 coils/hour at 100% OEE).

Factory Commissioning & Pre-Flight Checklist

Complete these verification checks before accepting and operating the machine on production lines:

  • Aperture & Ring Clearance: Confirm a minimum radial clearance of ≥ 75 mm between the shuttle carriage and the smallest planned coil ID (508 mm or custom 450 mm).
  • Friction Brake Calibration: Measure unwinding web tension using a handheld tensiometer; set to 20–35 N to prevent film neck-down or roll rupture.
  • True OD Overlap Verification: Measure overlap on the outer circumference of the wrapped product with an optical ruler; confirm it matches the target HMI value within ±3%.
  • Roller Tracking Stability: Verify that narrow coils (100–150 mm width) remain upright on the drive rollers during rotation, without axial drift or face-scuffing against side guide wheels.
  • Safety Interlock Response: Verify that opening the interlocked safety gate or hitting any E-stop trips the circuit and brings the orbital ring to a complete stop within ≤ 0.8 seconds (via dynamic braking resistors).

Engineering Selection & Request-for-Quote Checklist

Provide these production and material parameters to our engineering team to receive an exact drive-ratio quote:

  1. Dimensional Envelope: Minimum and maximum Coil ID × OD × Face Width (mm).
  2. Coil Mass Range: Minimum and maximum unit weight (kg).
  3. Surface Metallurgy: Bright drawn wire, galvanized, annealed, bare cold-rolled strip, or pre-oiled surface.
  4. Transit Routing: Domestic flatbed truck, climate-controlled warehouse, or cross-ocean containerized dry box.
  5. Consumable Combination: Plain stretch film, crepe paper, woven PP banding, or combined VCI + PE.
  6. Required Throughput: Coils per hour, shifts per day, and upstream line speed.
  7. Line Integration: Standalone manually-loaded cell (crane/c-hook) or fully automated in-line conveyor integration.

Machinery Safety & Compliance Standards

All FHOPE coil packaging systems are manufactured under strict European and international machine-safety directives:

  • EN ISO 12100:2010: Safety of machinery — General principles for design, risk assessment, and risk reduction.
  • EN 415-10:2014: Safety of packaging machines (Part 10: General requirements and orbital wrapping machine standards).
  • EN 60204-1:2018: Safety of machinery — Electrical equipment of machines (IP54 operator enclosure, industrial low-voltage controls).
  • ISO 13849-1 (PLd Level): Dual-channel safety gate interlocks and emergency-stop circuit integration.

Engineering FAQ

Q: Can a single machine process both slit steel coils and wire coils?

A: Yes. The FPW-300 and FPS-300 use identical drive geometries. Wire coils are supported by contoured polyurethane V-rollers or flat rollers with adjustable side stabilizers to prevent loose coil bands from splaying. Slit strips run on flat urethane rolls with synchronized side support rollers.

Q: What prevents sharp, sheared slit strip edges from severing the stretch film?

A: Sharp sheared edges can cut thin film under high radial tension. For slit strips, run a 90–110 GSM crepe paper or woven PE tape as the primary edge layer, followed by a stretch film outer wrap. You can also reduce mechanical film brake tension by 20% on the HMI.

Q: How does the system prevent inter-layer moisture under the film?

A: Solid stretch film is a barrier, not an active desiccant. To protect bare carbon steel or copper wire from ocean container corrosion, apply an inner layer of active VCI paper or VCI film directly against the metal. This ensures vapor corrosion inhibitors circulate inside the micro-environment, while the outer stretch film seals out ambient moisture.

Q: What happens if the wrapping material tears mid-cycle?

A: Standard machines include an optical or mechanical film-break sensor. If the web snaps, the drive engages dynamic braking to bring the ring to a stop within one revolution, flags a yellow fault on the stack light, and displays a “Film Rupture” alarm on the HMI without losing the cycle’s progress.

Procurement & Engineering Proposal Next Steps

+-------------------------------------------------------------+
|               48-Hour Technical Proposal Path               |
|                                                             |
|  1. Data Input        2. Kinematic Match   3. Formal Offer  |
|  [Submit Coils Specs] -> [Drive & Ring Ratios] -> [Drawing + Quote] |
+-------------------------------------------------------------+
  1. Submit Production Metrics: Email your coil dimensional envelope (min/max ID, OD, Width, Weight) and current handling method to info@fhopepack.com.
  2. Kinematic System Match: Our mechanical team verifies shuttle radial clearance, specifies the gearmotor drive ratios, and calculates real packaging cycle times.
  3. Engineering Deliverables: Receive an installation footprint drawing (AutoCAD/PDF), electrical load calculations, and an itemized commercial proposal within 24–48 hours.

Technical References

  • FHOPE Machinery Engineering Design Manual: Series FPW Wire Toroidal Wrappers and FPS Slit Strip Processing Units.
  • International Packaging Machinery Safety Directive: EN 415-10 (Specific safety regulations for orbital stretch wrappers).
  • International Electrical Standard: IEC/EN 60204-1 (Safety of machinery — Electrical equipment).
  • DIN EN ISO 12100: Standardized Mechanical Risk Assessment Protocols for Heavy Manufacturing Equipment.

Document Reference: ENG-FPW-FPS-SPEC-REV3.1 Content Validated by Chief Application Engineer, Industrial Packaging Machinery Division.

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