Beyond Visual Inspection: The Operational and Quality Benefits of Automated Surface Flatness and Roughness Measurement for Rolling, Coating, and Finishing Lines

High-resolution flatness measurement for critical flat-rolled products

Surface inspection is a consolidated topic which is of considerable importance in the manufacturing sector. A product that has no visible defects is unequivocal proof of the quality of the processes it has undergone to reach the finished product stage. Our solutions for surface inspection using dual technology, vision and two-dimensional lasers which are able to highlight shape and colour defects, up to, depending on the precision required, from macroscopic vision of flatness, wide range depressions, local depressions up to to the micrometric grain size The development of new optical technologies at low costs and ever-increasing accuracy has made it possible to add controls that were unthinkable until a few years ago.

Online Flatness & Planarity

From macroscopic imaging of flatness, wide range depressions, local depressions up to to the micrometric grain size

Remote Shark 2.0 - Industrial Monitoring Platform

| Inline Inspection

Flatness Performance

  • Measurement Range:±500 I-units / ±5% relative elongation
  • Resolution:0.1 I-unit (0.01% elongation)
  • Accuracy:±1 I-unit or ±2% of reading
  • Number of Zones:16 to 120 zones across strip width
  • Scan Rate:Up to 200 Hz full width scan

Sensor Technology

  • Technology:Laser array
  • Number of Sensors:Up to 64 independent measuring heads
  • Material Width:400 mm - 2200 mm (custom up to 2800 mm)
  • Line Speed:Up to 30 m/s (6000 ft/min)
  • Material Temp:Up to 400°C (with active cooling)

Control Integration

  • Interfaces:PROFINET, EtherCAT, Ethernet/IP
  • Output:Flatness deviation per zone / Shape factor
  • Actuator Control:Work roll bending / Shifting / Cooling zones
  • Data Logging:Full history with SPC reporting
  • Protection:IP54 (sensors with cooling)

Shape Factor Analysis

Multiple flatness indices: I-units, steepness, center wave, edge wave

Real-time Display

3D shape visualization and trend monitoring

Closed-loop Control

Direct integration with mill actuators for automatic flatness correction

Defect Classification

Automatic detection of quarter buckle, center wave, edge wave

How Flatness Measurement Works

Advanced laser-based stress measurement technology

Distance Measurement

Multiple laser sensors measure the distance to the strip surface across the entire width at high frequency

Profile Reconstruction

Advanced algorithms reconstruct the full 3D shape profile of the moving strip in real-time

Stress Calculation

Convert shape deviation into internal stress distribution (I-units or % elongation)

Actuator Feedback

Send correction signals to roll bending, shifting, or cooling systems for automatic flatness control

Industry Applications

Critical flatness control for demanding applications

Hot Rolling Mills

Flatness control for hot rolled strip and plate for steel and aluminum

Cold Rolling Mills

Precision flatness measurement for tinplate, automotive, and appliance grades

Aluminum Rolling

Flatness control for aluminum sheet, foil, and aerospace alloys

Tension Leveling Lines

Post-processing flatness verification and shape correction

Cut-to-Length Lines

Flatness inspection for precision blanks and sheets

Slitting Lines

Edge wave and crossbow detection for slit coils

Integrated Automatic Flatness Control (AFC)

From measurement to correction in milliseconds

1

Measure flatness across full width

2

Calculate shape error profile

3

Compute actuator correction

4

Send to mill actuators

5

Verify correction

Work Roll Bending Roll Shifting Zoned Cooling

Resources & Documentation

LGauge Flatness Measurement System - Datasheet

Complete technical specifications including measurement range, accuracy, sensor configurations, and installation drawings for all flatness gauge models.

AFC Integration Guide

Detailed documentation for integrating LGE flatness measurement with mill actuators including work roll bending, roll shifting, and zone cooling systems. Includes control algorithms and PLC integration examples.

Flatness Control Success Stories

Read how leading steel mills improved flatness quality by 65% and reduced rejects using LGE flatness measurement with automatic flatness control. Case studies include hot strip mills, cold mills, and aluminum rolling lines.