Metal Thickness Measurement

Measuring and inspection systems for the metal processing industry

Micro-Epsilon offers innovative measurement and inspection systems for the metals industry. Latest technologies are used for thickness, profile and surface measurements. Performance and quality, as well as reliability of products and services have made Micro-Epsilon one of the leading suppliers of inspection systems for optical thickness measurement used in the metals industry. Numerous, successful installations in 13 countries around the world in milling lines and processing lines speak for themselves.

Technology - innovative thickness measurement

Operating principle of thickness measurement

The principle of dimensional, geometric thickness measurement includes one optical distance sensor on each side of the material. The distance (=operating range) of both sensors is determined in a calibration process based on a certified measurement standard of which the thickness is added to the sum of the sensor signals in order to determine the current operating range. For thickness measurement during production, the difference between the sum of the distance signals and the value of the operating range is determined.
Special features:
  • Accuracy from ±1.2µm
  • Measuring ranges up to 50mm
  • Immersion depth up to 500mm
  • Special sizes on request
  • Measuring rate up to 49kHz

The MTS 7202.T is equipped with optoNCDT LL laser sensors, where the point-shaped laser beam is widened to a small line via a special cylindrical lens. The reflected light received is averaged using a special software algorithm. The interference caused by shiny metals is completely filtered out. MTS 7202.T is available in two different performance classes, both based on laser triangulation technology with several measuring ranges and measurement widths. The laser beams of both sensors are adjusted using a specially developed, optoelectronic tool offering the highest precision. Due to its high measuring rate, the system is ideal for monitoring highly dynamic processes. Automatic inline calibration ensures that measurements are not influenced by temperature.

Special features:
  • Linearity from ± 4µm
  • Measuring ranges up to 20mm
  • Immersion depth 50mm to 1000mm
  • Special sizes on request
  • Measuring rate up to 10kHz

The MTS 8202.T is equipped with laser triangulation sensors that ensure material-independent measurements. During the production process, the laser beams of both sensors are optimally adjusted using a specially developed optoelectronic tool that offers the highest precision. Due to its high measuring rate, the system is ideal for monitoring highly dynamic processes. Automatic inline calibration ensures that measurements are not influenced by temperature.

“Discrete laser line” innovation
By using special lenses, a laser beam is enlarged to form a static laser line and is projected onto the target surface. A high quality optical system projects the diffusely reflected light of this laser line onto a highly sensitive sensor matrix which detects during one measurement, depending on the sensor, a profile with 640 or 1280 measuring points. From this matrix image, the integrated controller calculates the distance information (z-axis) and the position alongside the laser line (x-axis) in a two-dimensional coordinate system.
Automatic calibration
The system is equipped with in-situ calibration in order to compensate e.g. for the effects of temperature fluctuations. Depending on the respective application, with this calibration either the reference/calibration piece or the C-frame can be positioned. Furthermore, the correct functioning of the system can be cyclically proven at any time. The analysis software enables easy, fast verification of the measurement system’s capability, which can be automated depending on the application.
Compensating for strip movement
Compared to laser point sensors, laser line triangulation measurement offers improved accuracy and stability. Tilt angles, warping and deformation of the material is recognized using profile sensors and is considered in the measurement results. This enables thicknessCONTROL MTS 820X.LLT to provide high quality thickness measurements with accuracies in the micrometer range, even when the metal sheet to be measured is several mm thick and tilted.
Special features:
  • Linearity of ±5 µm with measuring range of 40mm
  • Mouth width 300mm
  • Immersion depth 50mm to 800mm
  • Special sizes on request
  • Measuring rate up to 2kHz

The MTS 8202.LLT is equipped with laser triangulation scanners which means measurements are independent of the surface properties of the target material. Scaling or mirror effects of the metal surface are therefore absorbed. Furthermore, compared to point sensors, the system offers higher accuracy and a larger mouth width. Automatic inline calibration ensures that measurements are unaffected by temperature changes. The measurement line is arranged vertically to the material flow, enabling the system to cope with lateral strip tilting.

Special features:
  • Linearity of ±5 µm with measuring range of 40mm
  • Measuring rate up to 2kHz

The MTS 8201.LLT is equipped with laser triangulation scanners which means measurements are unaffected by the surface properties of the target material. Scaling or mirror effects of the metal surface are therefore absorbed. Furthermore, compared to point sensors, the system offers higher accuracy and a larger mouth width. The O-frame shaped mechanical system provides a temperature-compensated frame that compensates for any thermal changes of the measurement frame using additional sensor technology. The measurement line is arranged vertically to the material flow, enabling the system to cope with any lateral strip tilting.

Robust in difficult, industrial environments
Due to their high data rates, laser line sensors have proven to be very stable in harsh environments. In situations where there is a loss of 50% of the measuring points, e.g. due to steam, residual contamination with mill emulsion or reflections on shiny surfaces, the reference line of the usable point cloud still generates very stable measurement values and is thus superior to laser point technology.
Special features:
  • Optionally expandable with vertical linear axis for measuring range extension
  • Mouth width 300mm
  • Measuring rate up to 2kHz

thicknessCONTROL MTS 9201.LLT is specifically designed for harshest environments such as aluminum hot rolling mill applications. These systems stand out due to their solid steel frame. The optical sensors are water-cooled in order to ensure a longer service life. The integrated, electronic components remain in the specified temperature range, as the frame is purged with cold air. Another special feature is the patented, fully automatic monitoring of the linearity in the ‘parked’ position using a certified calibration standard. In this way, not only are thermal effects on the mechanics of the measuring frame monitored but also the factors affecting the sensor electronics, which are corrected automatically using a patented linearization process.