AMEPA chronology - Surface Roughness Measurement
Service - Surface Roughness Measurement
Field of application - Surface Roughness Measurement
Distribution partner - Surface Roughness Measurement
References - Surface Roughness Measurement
Health and safety system - Surface Roughness Measurement
CFM - Coal Flow Measurement
ESD - Electromagnetic Slag Detection
OFIS - Oil Film Thickness Measurement
OFM - Online Oil Film Measurement
RSD - Residual Steel Detection
SRM - Surface Roughness Measurement
TSD - Thermographic Slag Detection
MFM - Mould Flow Measurement
SFM - Ladle Purging Monitor
Slagmeter - Slag Thickness Measuring
Wavisurf - Online Waviness Measurement

Surface roughness of cold rolled sheets is an important parameter for the finishing process. Up to now, online roughness measurement was only possible with systems measuring in rolling direction. AMEPA developed a new optical system enabling a measurement under 45° or 90° – as stipulated by SEP 1940 and DIN EN 10049 – for all kinds of textures.

Technical data


Increasing customer requirements, complex metal forming, the necessity to raise productivity and to guarantee high surface quality with low tolerances are some of the numerous problems facing the steel maker. Although major improvements have been achieved, the roughness factor is not yet subject to online control.

Integrated into the production line, the online roughness measuring System SRM measures along the whole length of the strip and leads to a better understanding of the influence of the various production parameters.

The targets of the SRM system are:

  • Visualization and documentation of the roughness over the coil length
  • Timely detection of roughness out-of tolerance levels caused by e.g.:
    – wear of rolls
    – improper roll forces
  • Providing online data to determine the optimal point to change the rolls
  • Providing Ra as input for the roll force controller
  • Reduction of the number of offline measurements


The surface roughness measurements system SRM uses the light sectioning principle – a two dimensional laser triangulation, developed and patented by the Centre for Research in Metallurgy (CRM, Liège). This noncontact measurement principle uses a very thin laser line which is projected under a defined angle onto the measured surface where the originally straight laser line is distorted because it follows the surface topography. Microscope optics with a high resolution camera is used to take the image of the distorted laser line. The surface profile can be directly calculated from the image of the laser line.

In addition to the roughness value Ra, also Rz, RPc and other statistical values can be calculated. The SRM system offers a wide range of possibilities for the visualization of the online and the stored data. The examples of screens shot show the online Ra results over the coil length with the latest microscopic picture and as second example the visualization of stored measurements which can be accessed by via network.
Based on customer pre-set thresholds, warnings and alarms are indicated immediately if the roughness is out of tolerance so that the operator can start proper countermeasures without losing any time.

Technical data

  • Range (Ra) 0.3 – 5 µm
  • Resolution (Ra) 0.01 µm
  • Frequency max. 20 Hz
  • No calibration necessary
  • Working distance 28 mm
  • Automatic adjustment of optics
  • Motor driven optical adjustment
  • Storage of data > 1 year
  • Customer specific interface, e.g. OPC, Fieldbus or analog
  • Sensor dimensions 200 x 240 x 450 mm
  • Sensor weight approx. 16 kg
  • Customer specific traversing units


  • Moreas, G.; Bilstein, W.:“Industrial On-line micro-topography measurements“, Galvatech 2011, 21-24 June, Genova, Italy

  • Bilstein, W.; Berterman, K.:“Online roughness measurement in a coil line“, Iron and Steel Technology, August, 2008

  • Moreas, G.; Van De Velde, F.; Bilstein, W.: Advanced sensor for on-line topography in continuous lines, 26th Journées Sidérurgiques Internationales, 15-16 December 2005, Paris, France Download

  • Bilstein, W.; Enderle, W.; Moreas, G.; Oppermann, D.; Routschek,T.; Van De Velde, T.: Two Systems for On-Line Oilfilm and Surface Roughness Measurement for Strip Steel Production, Steel Rolling Conference, 19-21 Juni 2006, Paris, France. Download