🛠️ Evaluation Criteria
To compare tension compensation versus wrap‑count adjustment, use five measurable dimensions: anti‑looseness effectiveness, repeatability, material cost, setup effort, and compatibility with coil weight and geometry. Each dimension has a quantifiable threshold based on Fhope’s supplied specs (coil ID 300–500 mm, OD 400–850 mm, width 70–300 mm, weight 3–30 kg) and typical stretch‑film properties.
| Criteria | Why it matters | Measured in / conditions |
|---|---|---|
| Anti‑looseness effectiveness | Primary goal – does the coil stay tight after wrapping? | Pass/fail at specified tension and overlap rate |
| Repeatability | Can the same setting produce identical results coil after coil? | Typical deviation from set value; PLC‑driven vs. mechanical‑adjust |
| Material cost | Film consumption per coil | Number of layers × film width; actual film cost per roll |
| Setup effort | Time to change settings between coil sizes | Minutes per changeover (estimates – verify with supplier) |
| Weight/geometry compatibility | Does the method work for light vs. heavy coils, small vs. large OD? | 3–30 kg range, 300–850 mm OD (per Fhope’s parameters) |
🏗️ Option A: Tension Compensation (Mechanical Consistent Tension Device)
Fhope’s machine includes a consistent tension device that automatically adjusts film pull according to coil weight and diameter, preventing loose wraps caused by uneven tension. This is a purely mechanical compensation – the device uses a spring‑loaded mechanism (per Fhope’s spec: “packaging tension is adjustable by special mechanical device”). It works well for variable coil sizes without PLC reprogramming.
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How it works: The tension device maintains near‑constant film force as the ring rotates. On a 3 kg coil it avoids over‑tightening that could crush the product; on a 30 kg coil it prevents slack.
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Effectiveness: Supplier states the press‑down device and supportive rollers “avoid coil shaking in wrapping.” Tension adjustment is mechanical – no software needed.
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Cost impact: No extra film waste from over‑tension; the mechanical parts require periodic inspection (annual calibration not verified – confirm with supplier).
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Setup: Changeover between coil sizes takes under 5 minutes (estimate; actual time depends on operator skill and coil geometry – verify with supplier). Adjustable support rollers and press‑down height.
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Limitation: Cannot independently control layer‑by‑layer tension build‑up; only overall tension per wrap.
Tip: Use tension compensation as the primary lever when your coil weight varies frequently (e.g., 3 kg one hour, 20 kg next). The mechanical device adapts without PLC reprogramming.
📈 Option B: Wrap Count Adjustment (PLC‑Controlled Overlap & Speed)
Fhope’s PLC calculates the required number of wrapping layers based on coil OD and selected overlapping rate, ensuring enough film coverage to lock the coil tight. The machine’s “automatic material calculate function” and adjustable overlapping rate (via PLC) let you precisely control how many times the film crosses the coil surface. Wrapping speed can be set to 30–45 sec per piece (machine‑setting range – actual throughput may vary); ring speed up to 100 r/min.
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How it works: You set the target overlap (e.g., 50%) and the PLC computes the number of ring revolutions needed. More wraps = higher frictional lock on the coil.
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Effectiveness: Repeatable – once programmed, every coil gets the same number of wraps. Works best when coil geometry is consistent.
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Material cost: Directly proportional to number of wraps. Overlap rate of 50% uses ~1.5× the film of 30% overlap. (Actual film cost depends on roll price – consult your supplier.)
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Setup: Enter parameters via PLC panel – takes about 2 minutes after first programming. Changing between vastly different coil sizes may require re‑calculation.
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Limitation: Cannot compensate for tension drift if film roll is near end or temperature changes; assumes tension is fixed.
Key Point: Wrap count is the stronger lever for anti‑looseness when you need guaranteed layer thickness – e.g., for export protection or sharp coil edges. Pair it with the tension device for best results.
🛡️ Comparison Table
| Criterion | Option A: Tension Compensation | Option B: Wrap Count (PLC Overlap) |
|---|---|---|
| Primary mechanism | Mechanical consistent tension device | PLC‑calculated number of revolutions |
| Effect on looseness | Reduces slack from variable coil weight; prevents “necking” on light coils | Ensures minimum film coverage; locks outer wraps together |
| Repeatability | Typical ±5% tension deviation (spring‑loaded device – not from supplier spec; verify with Fhope) | ±0.5 layers deviation (digital control) |
| Material cost | Low – only one layer at correct tension | Medium‑High – extra layers increase film consumption by 30–100% |
| Setup time | Under 5 min (mechanical adjustments – estimate) | ~2 min (parameter entry) after first program |
| Best for | Mixed‑weight coils, soft coils (e.g., rubber hose) | Uniform‑weight coils, heavy coils requiring high holding force |
| Limitation | Cannot increase wrap count; tension drifts with film roll diameter | Cannot adjust tension per layer; assumes constant tension |
| Supplier data | Fhope: “packaging tension is adjustable by special mechanical device” | Fhope: “overlapping rate of the packing material according to requirement” |
| Cost of implementation | Included in standard machine (no extra hardware) | Included in standard machine (PLC feature) |
All above numbers are based on Fhope’s supplied parameters (coil ID 300–500 mm, OD 400–850 mm, width 70–300 mm, weight 3–30 kg) and typical packaging film assumptions. Deviation percentages are typical industry estimates unless sourced directly from Fhope’s documentation. Field validation is recommended for all settings.
⚙️ Selection Advice
Choose Option A (tension compensation) as the primary setting when your coil weight varies over 50% within a batch (e.g., 3 kg to 20 kg), and you want to minimize film waste. The consistent tension device will automatically adapt to each coil, avoiding both loose wraps on heavy coils and crushed edges on light ones. Verify that the machine’s press‑down device and adjustable support rollers (specified in Fhope’s features) are properly set during changeover.
Choose Option B (wrap count) as the primary setting when you have a stable coil size (e.g., always 20 kg, OD 700 mm) and the priority is absolute anti‑looseness for long‑distance shipping. Increase the overlapping rate until you see no film lift after 24 hours. Based on Fhope’s specs, a typical setting for heavy coils is 50–60% overlap at a machine setting of 30 sec/piece (actual time may vary). Combine with tension compensation set to medium – the two together eliminate most looseness problems.
If you mix both approaches (recommended):
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For light coils (<10 kg): Tension compensation does the heavy lifting; use low overlap (30%) to save film.
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For heavy coils (>20 kg): Set tension to max consistent level, then increase wrap count until the coil feels rigid.
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For variable batches: Program the PLC with two profiles (light / heavy) and toggle using the manual/automatic mode switch.
Caveat: All setup times and performance estimates are based on typical operation with Fhope’s machine. Actual results depend on operator technique, film quality, and environmental conditions. Always validate settings with a field trial. The machine runs on 380V 60Hz 3P and uses stretch film (OD 100–140mm, ID 50mm, width 90mm). Paper wrapping is available as an option.
For similar small‑coil packaging solutions, see {d.link1}. For a complete packaging line overview, check {d.link2}.
🛠️ Purchase‑Decision Checklist
Before finalizing your settings or ordering the machine, verify the following:
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[ ] Coil weight range – Does the 3–30 kg range cover all your products?
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[ ] Film tension calibration – Request a tension‑vs‑coil‑OD curve from the supplier.
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[ ] Overlap verification – Run a test at 30%, 40%, and 50% overlap; measure residual looseness after 24 h.
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[ ] Changeover time – Time how long it takes to switch from OD 400 mm to OD 800 mm (estimate given by supplier).
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[ ] Warranty & lead time – 1‑year warranty, 35 working days production (per Fhope terms).
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[ ] Payment terms – 50% deposit, 50% before delivery; price valid 30 days.
🛡️ Compliance Note: This equipment is designed to meet ISO and CE requirements. Verify with the manufacturer.
🏗️ FAQ
Q: If I increase wrap count, will it always solve looseness?
A: Not if the base tension is too low. Wrap count adds layers but cannot compensate for a slack first wrap. Always set tension compensation first, then adjust count.
Q: Does the Fhope machine support automatic tension adjustment in real time?
A: The “consistent tension device” is mechanical rather than electronic. It maintains a set tension level throughout a coil, but the level must be pre‑adjusted per coil range. Real‑time adaptation requires a servo‑driven system – confirm with supplier.
Q: How do I calculate the optimal wrap count for my coil?
A: Use the overlap rate formula: Layers needed = 1 / (1 – overlap decimal). For 50% overlap, layers = 2. Then multiply by 2 for a safety margin. Example: For a coil with OD 600 mm and width 200 mm, if you want 50% overlap, the PLC will apply 2 full revolutions of film per layer. After two layers, the outer wrap is locked. Always test one coil and inspect after 24 h.
Q: Can the machine handle paper wrapping as an alternative to film?
A: Yes, paper is listed as an option. Note that paper has lower elasticity, so tension compensation becomes even more critical to avoid tearing. Confirm paper roll dimensions (OD 100–140mm, ID 50mm, width 90mm) with the supplier.
