How a Coil Wrapping Machine Works for Steel Coil Packing

Executive summary

How a coil wrapping machine works for steel packing comes down to two motions. A ring carries the packaging material through the coil eye and round the cross-section, while carrier rollers turn the coil slowly on its own axis. The speed ratio between the two movements determines the wrap overlap. On our FPW-300, steel coils of 600–1,200 mm OD, 508–610 mm ID, and up to 1,000 kg roll in, are wrapped in paper or film, and roll out.

Table of Contents

The two motions of a coil wrapping machine

A steel coil has a hole through the middle, so the wrap has to go through it. The machine does this by coordinating two synchronized motions:

  1. Orbital rotation through the coil eye. A ring passes vertically through the inner diameter, loops over the outer crown and returns beneath the base. As the ring turns, the dispenser roll mounted on it lays a continuous band of stretch film or paper across the coil cross-section.
  2. Coil rotation on carrier rollers. Concurrently, motorized carrier rollers support the coil from below and rotate it slowly about its own horizontal axis.

Each successive band lands a little further round. After one full 360° turn of the coil, the whole outer surface and side faces are uniformly covered against moisture, dust and handling damage.

Main parts of our ring wrapper

  • Wrapping ring assembly. A vertical ring with an opening gate segment: it unlatches to admit the coil into the ring plane, locks securely before rotation begins, and carries the film or paper dispenser roll with an adjustable tension brake. The gate opening mechanism is confirmed per machine specification.
  • Coated carrier rollers. Heavy-duty drive rollers in the machine chassis that support the full coil weight. The roller surfaces carry an abrasion-resistant protective coating, so the coil never sits on bare steel — no scratching, indentations or edge scuffing.
  • Side guide arms. Guide arms that steady the coil on the rollers and keep it centred during rotation.
  • Safety perimeter guard. A mesh guard enclosure surrounding the rotational sweep of the ring, closing off the pinch and shear zones during automatic operation.
  • Operator control cabinet. Beside the machine, outside the guard: pushbuttons, indicator lights, the emergency stop and the one-key automatic cycle start.

How one steel coil is wrapped

  1. Roll in. The operator rolls the steel coil onto the carrier rollers, eye in line with the ring.
  2. Tie on. With the machine stationary, the material end is fixed to the coil.
  3. Start. The operator returns to the cabinet and starts the automatic cycle with the one-key start.
  4. Wrap. The ring wraps while the carrier rollers turn the coil through exactly one full revolution (or multiple turns if multi-layer wrapping is specified).
  5. Cut and roll out. The machine stops automatically, the material is cut and secured, and the coil is tipped off the rollers and rolled away.

Rolling in and out suits lighter coils (typically under 200–300 kg). Heavier coils up to 1,000 kg are loaded and unloaded by overhead crane with a C-hook or coil grab, or by a powered infeed conveyor.

The speed ratio that sets overlap

Overlap is not set on the ring. It is governed by the kinematic speed ratio between the carrier rollers and the ring. Let:

  • n = ring speed in wraps per minute
  • N = wraps required to cover the coil once
  • a = advance per wrap, measured at the coil OD
  • v = carrier roller surface speed at the coil OD

The governing relations are:

  • The coil must complete one full rotation on the rollers while the ring completes exactly N wraps.
  • The carrier roller surface speed at the coil OD is v = a × n.
  • The wrapping time is t = N ÷ n.

To increase overlap, the rollers turn more slowly relative to the ring (a smaller advance a); to save material, the roller speed is increased. Independent variable frequency drives let both speeds, the material tension and the overlap be adjusted.

Worked example: setting the rollers for 30% overlap

Illustrative steel coil: ID 508 mm, OD 1,000 mm, width 250 mm, 100 mm paper, 30% overlap wanted at the OD.

Step Calculation Result
Advance per wrap at OD a = 100 × (1 − 0.3) 70 mm
Wraps per coil N = π × 1,000 ÷ 70 ≈ 45
Advance at the ID π × 508 ÷ 45 ≈ 35 mm, so ≈ 65% overlap
Roller surface speed v = 0.070 m × n 0.07 × n (m/min, n in wraps/min)
Paper per coil 45 × 2 × (246 + 250) mm ≈ 44.6 m
Wrapping time t = 45 ÷ n (45 ÷ n) minutes

Result. For 30% at the outside, the rollers must move the coil surface 70 mm for every ring wrap. Because the ID is roughly half the OD, the advance shrinks to about 35 mm inside the eye, a tighter ≈65% overlap at the bore — inherent to eye-through wrapping, not a setting to correct. Whatever ring speed is chosen, the roller speed follows it in that ratio, and the coil needs about 45 wraps and 44.6 m of paper. Doubling the ring speed halves the time only if the rollers double too.

FPW-300 data for steel coils

Item Specification
Coil ID 508–610 mm
Coil OD 600–1,200 mm
Coil width 100–300 mm
Coil weight 20–1,000 kg
Wrap materials PVC, LLDPE, PE, paper, HDPE
Material roll core 50 mm ID
Material roll OD 100–450 mm
Material roll width 100–150 mm
Overlap 10%–90%, adjustable
Power 1.5 kW, 380 V, 50 Hz, 3-phase
Air supply 4–6 bar (0.4–0.6 MPa)
Chassis height Adjustable, to centre the ring on the coil eye
Rollers Protective coating
Compliance CE certified; ISO 9001 quality system
Warranty 2-year manufacturer warranty
Nominal throughput Up to 60 coils per hour [manufacturer rating]

The nominal throughput is a manufacturer rating under favourable coil sizes and feeding; the hourly rate for your line is confirmed at quote, as the machine can be built to your coil specification.

Selection checklist

  1. Coil ID, OD, width and weight.
  2. Loading: rolling, crane or conveyor.
  3. Material: paper, film or both.
  4. Overlap wanted at the OD.
  5. Coils per shift.
  6. Voltage.

Safety: EN 415-10 and ISO 12100

The wrapper is built to EN 415-10 and its risk assessment follows ISO 12100:2010. The ring passing through the eye and the turning rollers are the hazards: the ring presents pinch and shear points at the eye, and the driven rollers create nip points beneath the coil. The mesh guard closes the ring area, and the operator starts the cycle only from the cabinet, outside the guard. Tie-on and roll-off are done with the machine stopped, and the E-stop and error light are on the cabinet.

Engineering FAQ

Q: Why does the coil need to turn? A: The ring lays one band at a time across the section; the coil turning brings fresh surface under the ring until it is covered.

Q: What sets the overlap? A: The ratio of roller speed to ring speed. The ring speed sets the time, and the roller speed follows it.

Q: Can it wrap paper and film? A: Yes. The dispenser accepts PVC, LLDPE, PE, HDPE and paper on 50 mm cores, so the line can switch between moisture sealing and edge protection.

Q: Which standard applies? A: We work to EN 415-10 for this wrapper and document the ISO 12100 risk assessment in the CE file.

Next step

  1. Send coil ID, OD, width and weight to info@fhopepack.com.
  2. We set the wrap count, material and loading method.
  3. We reply within 24 hours with a layout and quotation.

Sources

Last reviewed: 2026-10-18

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