Executive summary The automatic steel coil strapping machine provides through-the-eye radial strapping for slit coils delivered inline on roller conveyors. The integrated strapping station lowers the strapping head, drives high-tensile steel strap through the vertical coil eye via an automated sword mechanism, and tensions and seals the joint. This process secures nested coil wraps against telescoping during handling, warehousing, and inter-plant transit without requiring the slit coil to leave the roller pass line.
Table of Contents
- What the machine does
- Why strap through the eye
- Straps per coil
- What we set per coil
- Selection checklist
- Safety
- Engineering FAQ
- Next step
- Related reading
- Sources
What the machine does
The machine automatically binds slit steel coils through the core center (eye) on an active production line:
- Infeed. The flat slit coil enters the strapping station on the powered roller conveyor with the core axis positioned vertically (eye-to-sky).
- Head down. The overhead strapping head and guide assembly lower to engage the top face and outer rim of the stationary slit coil.
- Through the eye. A precision vertical sword piercing mechanism indexes through the coil center, guiding high-tensile steel strap through the inner bore and around the outer circumference via a closed reciprocating track.
- Seal. The strapping head pulls the strap to set tension, locks it, and creates a secure joint before retracting clear of the package.
- Cycle completion. The strap guide track opens, the head returns to home position, and the conveyor or turntable prepares the coil for the next strap location or outfeed.
Why strap through the eye
- Holds the wraps: Radial straps run through the bore to lock inner and outer wraps tightly together, preventing axial telescoping and interlayer shifting during crane handling or transport.
- Steel strap: High-strength cold-rolled steel strapping provides the tensile rating required to contain dense, springback-prone slit steel coils.
- Flat coil stability: Strapping the coil in an eye-vertical (flat) orientation eliminates tipping risks and avoids the need for coil downenders ahead of downstream sorting or stacking.
- Inline processing: The strapping cycle takes place directly on the roller conveyor bed, maintaining continuous product flow along the slitting line exit.
Straps per coil
Strapping throughput depends on the number of radial bands applied, strapping cycle duration, and coil indexing time:
Worked example (illustrative).
| Item | Value |
|---|---|
| Straps per coil (illustrative) | 4 |
| Strap cycle (illustrative) | 20 s |
| Index between straps (illustrative) | 5 s |
| Time per coil, 4 × (20 + 5) | 100 s |
| Coils per hour, 3,600 ÷ 100 | 36 |
Note: Cycle and indexing times above are illustrative engineering benchmarks. Actual cycle times vary depending on coil outer diameter (OD), inner diameter (ID), strip face width, and indexing turntable rotation speed.
What we set per coil
The human-machine interface (HMI) and programmable logic controller (PLC) allow operators to match mechanical settings to varying slit coil dimensions:
| Setting | Depends on | Factory Benchmark Parameters [manufacturer rating] |
|---|---|---|
| Straps | Number per coil | 2, 3, 4, or 6 radial straps per package based on downstream transport limits |
| Strap | Steel width and thickness | Slit Coil Eye Strapping Machine uses high-tensile steel strap: width 31.75 ± 0.13 mm, thickness 0.8–1.0 mm; cold-rolled medium carbon steel with yield point (YP) ≥ 900 MPa; finish: blued, galvanized, painted, or waxed |
| Index | Coil rotation between straps | Integrated rotation rollers or center indexing turntable calculate angular intervals (e.g., 90° for 4 straps, 60° for 6 straps) |
| Conveyor | Coil size | Roller conveyor spacing and lateral guide limits adjusted for target coil weight, OD, ID, and width |
The core strapping assembly relies on a rigid head lifting mechanism and an automated vertical sword piercing mechanism running a closed reciprocating winding loop to pass the steel strap cleanly through tight center bores.
Machine lineage note [manufacturer rating]: For facilities requiring non-metallic strapping, our product portfolio includes an automated PET radial coil strapping machine configured for 12 mm × 0.8–1.2 mm polyester strapping across horizontal and perpendicular axes. For jumbo steel coils, heavy-duty radial strapping machines provide 360° rotating heads with service life ratings up to 1 million cycles.
Selection checklist
- Coil OD, ID, width and weight.
- Straps per coil.
- Strap size.
- Coils per hour.
- Line layout.
- Wrapping after strapping or not.
Safety
- Keep clear of the strap head while it moves.
- Wear gloves when handling steel strap.
- Lock out before clearing a strap jam.
- For CE markets, the machine is designed to ISO 12100 and EN 415-10.
Engineering FAQ
Q: How does it strap a slit coil? A: A vertical sword extension passes the steel strap down through the inner coil core (eye), channels it around the external diameter through a closed guide arch, pulls it to preset tension, and seals it.
Q: Why through the eye? A: Radial straps placed through the center eye mechanically bind every individual wrap together, preventing inner-ring pop-out and telescoping under lateral G-forces.
Q: How many coils per hour? A: 36 coils per hour when applying 4 radial straps per coil under the baseline cycle parameters shown in our worked example (100 s total cycle per coil).
Q: Which strap does it use? A: The standard through-eye slit coil strapping machine runs heavy-duty steel strap (typically 31.75 ± 0.13 mm × 0.8–1.0 mm cold-rolled steel, YP ≥ 900 MPa [manufacturer rating]). For non-metallic packaging lines, dedicated PET strapping machines using 12 mm strap are available in the machine family.
Q: Does the coil leave the conveyor? A: No. Strapping occurs directly within the powered conveyor station, using integrated roll lifters or turntable rotators to index the coil between strapping passes.
Q: Which standards apply? A: For CE markets, machinery design complies with ISO 12100:2010 (safety of machinery risk reduction) and EN 415-10:2014 (safety requirements for general strapping machines).
Next step
We match a slit coil strapping machine in three steps:
- Submit your layout drawing with coil sizes, straps per coil and coils per hour, to info@fhopepack.com.
- Receive a proposal within 48 hours with the machine data and layout.
- Book a site survey so we confirm the slitter exit.
Related reading
- Turnstile Slit Coil Strapping Machine
- Narrow Steel Strip Coil Packing Line
- Vertical Slit Coil Packing Line: How It Works
- Slit coil packing line
Sources
- Machine content: FHOPE engineering team, Slit Coil Eye Strapping Machine technical specifications
- YouTube: the video on YouTube
- Straps per coil: our worked example, illustrative values
- Standards scope: ISO 12100:2010; EN 415-10:2014
- Proposal timing: approved house CTA (proposal within 48 hours)
Last reviewed: 2026-10-29
