Eye-Through Steel Coil Wrapping Machine: Engineering Guide & FPS-400 Specs

Executive Summary

The eye-through steel coil wrapper is an orbital packaging machine engineered for slit strip coils, cold-rolled coils, and non-ferrous metal rolls. A driven C-shaped rotating ring carries a roll of stretch film, crepe paper, or woven composite tape directly through the coil eye (bore) while polyurethane (PU)-coated drive rollers rotate the coil around its horizontal axis. This coordinated motion applies a tightly bonded protective shell covering the coil bore, outer diameter (OD), and both side faces. The standard FPS-400 platform handles coils with 508 mm or 610 mm inner diameter (ID), 800–1,400 mm OD, 100–400 mm width, and payloads from 100 kg to 2,000 kg, providing fully programmable overlap rates from 10% to 90%.

A slit steel strip coil rests securely on the PU-coated support rollers while the heavy-duty C-ring orbits continuously through the central bore. Each revolution of the ring lays down a precise wrap band across the radial cross-section of the coil, while controlled coil rotation indexes the package forward, sealing the metal against corrosion, moisture ingress, and transit friction.

Table of Contents

How the Eye-Through Wrapper Works

Standard turntable pallet wrappers cannot package annular steel coils because standard horizontal rotation leaves the inner bore and side faces exposed. The eye-through orbital wrapper solves this mechanical constraint through two synchronized kinematic axes:

  1. Orbital Ring Rotation (C-Ring): The C-shaped ring features an engineered peripheral clearance gap. During loading, the ring homes automatically with the gap positioned at top dead center. The coil wall enters through this gap, and the ring orbits continuously through the eye. The roll dispenser mounted on the ring discharges wrapping material around the coil wall cross-section on every cycle.
  2. Coil Indexing Rotation: Polyurethane-lined drive rollers beneath the coil rotate it along its horizontal axis at a controlled surface speed. Each consecutive band of packaging material overlaps the preceding band by a predetermined percentage.
  3. Cycle Completion and Cut-Off: Once the coil completes a 360° rotation plus a programmable reinforcement overwrap, the C-ring returns to its top-gap home position. An automatic or manual mechanism cuts the material, and the trailing edge is smoothed against the side face.

The overlap ratio is determined by the speed ratio between the orbital ring VFD and the coil roller VFD. Smooth ramp-up and ramp-down profiles prevent film slippage, tension spikes, and sharp edge cuts on narrow slit strips.

Main Components and Engineering Functions

Component Technical Function & Construction
C-Ring (Orbital Rotor) High-strength circular ring with a fixed clearance opening; orbits the material roll through the bore. The top-gap parking design enables unhindered overhead crane loading.
PU-Coated Drive Rollers High-load polyurethane vulcanized rollers that rotate the coil smoothly without scoring, scratching, or marring cold-rolled strip finishes.
Mechanical Film Dispenser Adjustable friction-plate tension brake system on the material spindle to prevent slack, neck-in distortion, or wrinkling.
PLC & HMI Control Architecture Siemens PLC system paired with an industrial touchscreen; automates overlap ratio calculations, variable speed profiles, and top-gap ring positioning.
Integrated Safety Systems Class 4 safety light curtains, perimeter guards, and hardwired E-stop circuits to de-energize mechanical drives upon zone breach.

Compatible Packaging Materials

The FPS-400 runs standard industrial packaging media, including LLDPE stretch film, stretch paper, VCI (vapor corrosion inhibitor) crepe paper, and high-tensile HDPE woven tape. Single-layer and composite double-layer configurations are supported:

  • Single Layer: High-yield stretch film or anti-rust VCI paper for domestic storage and short-haul logistics.
  • Dual Layer (Simultaneous Dispensing): Applies contact crepe paper / VCI paper on the inside face against the steel surface, covered simultaneously by an external waterproof stretch film layer. See how steel coils are packed with paper and stretch film.
  • Dispenser Core Dimensions: Inner core ID: 50 mm (2 inches); material roll OD: 100–450 mm; roll width: 100–150 mm.

Engineering Specifications (FPS-400)

Parameter Standard Range (FPS-400)
Coil Inner Diameter (ID) 508 mm / 610 mm
Coil Outer Diameter (OD) 800–1,400 mm
Coil Width (Face Width) 100–400 mm
Maximum Coil Weight 100–2,000 kg
Film Overlap Range 10%–90% (HMI Programmable)
Material Roll Parameters Core ID: 50 mm; Roll OD: 100–450 mm; Width: 100–150 mm
Installed Drive Power 4.0 kW
Pneumatic Supply Pressure 0.5–0.7 MPa (5–7 kgf/cm² / 70–100 psi)
Automation Hardware Siemens PLC platform with digital touchscreen HMI
Ring Orbital Speed & Cycle Time Configured per target cycle time and coil weight

Note: For coil dimensions exceeding standard envelope boundaries, custom C-ring frames, roller base pitches, and high-capacity hydraulic shuttle stations are engineered to order.

Worked Calculation: Material Consumption per Coil

Calculation Basis

  • Coil Dimensions: OD = 1,200 mm, ID = 508 mm, Width (W) = 300 mm
  • Packaging Material: 100 mm width, applied at a target 50% overlap
  • Kinematic Rule: Overlap is set at the coil bore (ID), where surface linear speed is lowest and circumference is smallest, ensuring that the package remains sealed even as bands fan out across the larger outer circumference (OD).
Step Mathematical Deduction Engineering Value
1. Inner Bore Circumference C_bore = π × ID = π × 508 mm ≈ 1,596 mm
2. Advance per Orbit (at ID) Adv = Width × (1 − Overlap) = 100 mm × (1 − 0.50) 50 mm
3. Required Ring Revolutions N_rev = C_bore ÷ Adv = 1,596 mm ÷ 50 mm ≈ 32 turns
4. Coil Wall Cross-Section Perimeter L_turn = 2 × ((OD − ID) ÷ 2) + 2 × W = (1,200 − 508) + 2 × 300 1,292 mm (1.292 m)
5. Net Material Consumption L_total = N_rev × L_turn = 32 × 1.292 m ≈ 41.3 m

Engineering Analysis: Sealing this coil requires approximately 32 ring turns and 41.3 meters of material per layer. This represents the net theoretical coverage. Practical gross consumption includes lead-in clamping, trailing edge cut-offs, and an extra 2–3 turns of lap overlap. When running LLDPE stretch film, pre-stretch tension elongation reduces the actual linear roll payout required. Ring speed determines the ultimate process cycle time (Cycle Time = N_rev ÷ Ring RPM).

Industrial Applications

  • Slitting Center Production Lines: Fast wrapping of narrow slit strip bundles directly off recoiler turntables.
  • Cold-Rolled & Galvanized Steel Export: Multi-layer moisture-barrier packaging to prevent white rust formation during ocean freight.
  • Copper & Aluminum Coil Finishing: Scratch-free handling with non-marking PU rollers and crepe paper barrier layers.
  • Overhead Crane Integration: Top-gap open ring design permits overhead C-hook, scissor tong, or hoist loading directly onto the roller cradle.
  • Automated Coil Handling Integration: Inline integration with turnstiles and downenders transitioning coils between axes. See eye-to-wall to eye-to-sky coil packaging systems.

Technical Selection Checklist

Provide the following line parameters to ensure correct orbital sizing and roller selection:

  1. Dimensional Spectrum: Minimum and maximum coil ID, OD, strip width, and individual coil weight.
  2. Material Handling Method: Overhead crane (C-hook/slings), forklift, walking beam, or automated coil car.
  3. Packaging Media Specification: Stretch film gauge, VCI crepe paper basis weight, woven belt width, or dual-material packaging requirement.
  4. Target Throughput: Average coils per hour / shifts per working day.
  5. Site Utilities: Available factory voltage/frequency (e.g., 380V/480V 3-phase) and compressed air line pressure.

Safety Compliance: EN 415-10 and ISO 12100

Orbital eye-through coil wrappers operate under European Standard EN 415-10 (Safety of packaging machines — wrapping machines other than pallet wrappers) and general design risk assessment standard ISO 12100:2010.

Primary mechanical hazards include ring rotation entrapment and roller pinch points. Standard machine integration incorporates:

  • Category 4 / PL e safety light curtains covering the open loading station.
  • Controlled mechanical locking preventing ring movement during coil loading and unloading.
  • Top-gap orbital parking confirmation via dual inductive safety proximity sensors.
  • Full CE documentation, risk assessment validation, and LOTO (Lockout/Tagout) disconnects.

Engineering FAQ

Does the eye-through wrapping process seal the inner coil bore?

Yes. Because the C-ring tracks directly through the inner diameter, the wrapping material covers the bore wall, both vertical side faces, and the outer diameter in a single continuous orbital operation.

Can the machine apply protective paper instead of stretch film?

Yes. The dispenser assembly handles crepe paper, VCI corrosion-inhibiting paper, and HDPE woven belts. An optional dual dispenser can wrap paper and stretch film simultaneously in a single pass.

How is the material overlap ratio adjusted?

The overlap ratio (10% to 90%) is entered directly on the HMI touchscreen. The PLC automatically modulates the frequency inverter running the roller rotation drives relative to the ring motor.

How is the steel coil loaded onto the rollers?

The C-ring stops with its gap parked at top dead center. This open throat allows overhead crane C-hooks or shop hoists to lower the steel coil directly onto the PU roller bed without colliding with the ring structure.

Project Quotation & Next Steps

  1. Submit Parameters: Email your coil minimum/maximum ID, OD, width, and weight distribution to info@fhopepack.com.
  2. Kinematic Matching: Our packaging engineering team evaluates C-ring throat clearance, PU roller spacing, and cycle timing.
  3. Formal Proposal: Receive a complete engineering drawing, technical data sheet, and price quotation within 24 hours.

References

  • FHOPEPACK Engineering Documentation: FPS-400 Orbital Eye-Through Steel Coil Wrapping Machine.
  • EN 415-10: Safety of Packaging Machines — Part 10: General Requirements.
  • ISO 12100:2010: Safety of Machinery — General Principles for Design — Risk Assessment and Risk Reduction.

Last reviewed by Principal Packaging Engineer: 2026-10-19

Last updated: 2026-10-29

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