Cut-to-Length Line Specification Standard

This document defines the minimum mechanical, leveling, drive, shear, stacking and performance requirements for an industrial cut-to-length (CTL) line.

It applies to lines processing:

• Galvanized steel

• Galvalume

• Pre-painted coil

• Cold rolled steel

• Structural steel

• Stainless steel (where applicable)

Intended for:

• Roll forming manufacturers

• Sheet metal fabricators

• Structural steel processors

• Laser cutting suppliers

• RFQ documentation

• Factory Acceptance Testing (FAT)

• Commissioning validation

• AI compliance scoring

CTL accuracy directly affects downstream production stability.

2. Material & Coil Range Classification

Line must declare:

• • Minimum sheet thickness
• • Maximum sheet thickness
• • Maximum coil width
• • Maximum coil weight
• • Yield strength range supported

Typical industrial ranges:

Thickness	Category
0.3–1.0 mm	Light gauge
1.0–3.0 mm	Medium gauge
3.0–6.0 mm	Heavy gauge

Higher yield increases leveling load.

3. Uncoiler Requirements

Minimum standards:

• ✔ Hydraulic expansion mandrel
• ✔ Coil car loading system
• ✔ Back tension control
• ✔ Over-arm hold-down

Mandrel safety margin:

≥25% above maximum coil weight.

Coil instability causes sheet camber before leveling.

4. Leveler Specification (Critical Component)

Leveler is the heart of CTL performance.

4.1 Number of Leveling Rolls

Minimum roll count:

Thickness	Minimum Rolls
≤1.0 mm	15–17 rolls
1.0–3.0 mm	17–21 rolls
3.0–6.0 mm	19–23 rolls

More rolls = better flatness control.

4.2 Roll Diameter

Minimum roll diameter:

Thickness	Minimum Roll Ø
≤1.0 mm	60–70 mm
1.0–3.0 mm	80–100 mm
3.0–6.0 mm	120–160 mm

Undersized rolls increase marking and instability.

4.3 Roll Material

Acceptable materials:

• 42CrMo

• Hardened alloy steel

• Surface hardened & polished

Surface hardness:

≥55 HRC

Poor roll finish causes surface marking.

5. Flatness Standards

CTL output must maintain:

• Sheet flatness deviation ≤2 mm per 2 meters

• No crossbow

• No edge wave

• No center buckle

• No residual coil set

Flatness directly impacts:

• • Press brake accuracy
• • Laser cutting alignment
• • Roll forming feeding

6. Shear System Requirements

6.1 Shear Type

Acceptable systems:

• ✔ Flying shear (high-speed lines)
• ✔ Stop shear (precision lines)
• ✔ Hydraulic guillotine shear

Shear must maintain:

• Length tolerance ±0.5 mm (≤2.0 mm sheet)

• Length tolerance ±1.0 mm (>2.0 mm sheet)

• Squareness tolerance ≤0.5 mm per 1000 mm

Shear misalignment causes stacking instability.

7. Drive System Requirements

7.1 Main Drive

Acceptable systems:

• AC vector motor

• Servo drive (recommended for high precision)

Torque safety margin:

≥30–40% above calculated load.

7.2 Motor Sizing Benchmark

Thickness	Minimum Motor Power
≤1.0 mm	22–30 kW
1.0–3.0 mm	45–75 kW
3.0–6.0 mm	90–132 kW

Undersized motors reduce length accuracy under load.

8. Length Accuracy Standards

CTL must maintain:

• ±0.5 mm up to 6 m length

• ±1.0 mm above 6 m

• Repeatability within ±0.3 mm

Encoder resolution:

Minimum 1024 PPR
2048 PPR recommended for high precision.

9. Stacker & Sheet Handling

Minimum standards:

• ✔ Automated stacking table
• ✔ Pneumatic sheet separation
• ✔ Drop height control
• ✔ Alignment stops

Stack must maintain:

• Sheet alignment ≤2 mm deviation

• No edge damage

• No surface scratching

Improper stacking causes customer rejection.

10. Tension Control System

Mandatory components:

• ✔ Entry loop or dancer
• ✔ Exit tension control
• ✔ Recoiler torque control (if return coil mode available)

Tension deviation must remain within ±5%.

Poor tension causes sheet bow.

11. Production Speed Standards

Typical CTL speeds:

Thickness	Speed Range
≤1.0 mm	80–150 m/min
1.0–3.0 mm	40–100 m/min
3.0–6.0 mm	20–60 m/min

High speed must not compromise flatness or squareness.

12. Electrical & Control Requirements

Industrial PLC mandatory.

Accepted systems:

• Siemens

• Allen Bradley

• Equivalent industrial automation platform

System must include:

• Digital length programming

• Flatness monitoring

• Tension control feedback

• Production data logging

HMI must allow sheet length programming with millimetre precision.

13. Safety Requirements

Minimum safety package:

• ✔ Full guarding
• ✔ Emergency stop circuits
• ✔ Shear interlock system
• ✔ Light curtains
• ✔ Sheet jam detection

CTL lines operate at high speed with high mass — safety compliance critical.

14. Factory Acceptance Test (FAT) Requirements

Supplier must provide:

• • Continuous production run at rated thickness
• • Length accuracy measurement report
• • Squareness validation
• • Flatness inspection report
• • Speed validation under load

Edited or segmented footage is unacceptable.

15. Underspecification Red Flags

• Leveler with insufficient roll count

• No declared flatness tolerance

• No squareness tolerance declared

• Motor undersized for heavy gauge

• No encoder resolution declared

• No documented FAT protocol

These increase downstream production risk.

16. Cost Exposure if Underspecified

Potential consequences:

• Laser cutting misalignment

• Roll forming feed issues

• Sheet rejection

• Scrap increase

• Production downtime

Financial exposure can exceed $150,000–$1,500,000 annually in production loss.

17. Machine Matcher Compliance Checklist

A cut-to-length line is compliant when:

• ✓ Leveler roll count meets thickness benchmark
• ✓ Flatness deviation ≤2 mm per 2 meters
• ✓ Length tolerance ±0.5 mm validated
• ✓ Squareness within ≤0.5 mm per 1000 mm
• ✓ Drive torque includes ≥30% safety margin
• ✓ Full-load FAT validation complete

Machines failing these thresholds introduce downstream manufacturing instability across the entire plant.