Radar sensors for high-precision inline dimension measurement

Walzwerk des Stahlwerks von ArcelorMittal in Rodange © ArcelorMittal

An OndoSense radar system measures the width and thickness of slabs, billets or beams with sub-millimeter accuracy. This saves time and costs and reduces CO2 emissions.

Thickness measuring system for semi-finished steel products with one of the two radar sensors in the center of the measuring frame. © ArcelorMittal
Thickness measuring system for semi-finished steel products with one of the two radar sensors in the center of the measuring frame.
© ArcelorMittal

Together with radar specialist OndoSense, ArcelorMittal has successfully implemented a radar sensor solution for the precise measurement of semi-finished steel products. Based on the OndoSense apex radar sensors, ArcelorMittal was able to significantly automate and improve product monitoring – even in the harsh conditions of the hot rolling mill with dust, steam, vibrations and red-hot steel with temperatures up to 1300 °C. As a result, the dimensions of slabs, billets and beams are now reliably recorded at an early stage in the rolling process with an accuracy of less than 1 mm. The result: Inline dimensional measurement protects the machines in the rolling mill, reduces costs and emissions through less scrap, and increases the utilization and safety of the plant. ArcelorMittal plans to introduce the radar sensor solution in additional hot rolling mills in the near future to further automate and digitalize steel production.

“Our new radar sensor solution helps to increase the productivity of our rolling mills for long products. Thanks to the inline measurement process, we can adjust the rolling of our products early in the process, which brings many advantages. OndoSense not only offers a very reliable and robust product: the OndoSense team also supported us very effectively and quickly during the integration process,” explains Thomas Hilbert, Research & Development Engineer at ArcelorMittal Luxembourg.

Illustration of thickness measurement of metal slabs with the OndoSense apex radar sensor system. © OndoSense
Illustration of thickness measurement of metal slabs with the OndoSense apex radar sensor system. © OndoSense

Modern solution sought – to replace manual measurement

Automated width and thickness measurement of steel products is a challenging task in a production environment with steam, dust, poor lighting conditions and product temperatures up to 1300 degrees Celsius.

Prior to the implementation of the radar sensor solution for reliable and precise inline dimensional measurement, steel long products at ArcelorMittal were measured manually with a caliper gauge. This method is considered a standard procedure for width and thickness measurement of long products in the steel industry. “Manual inspection of product dimensions following hot rolling has been considered sufficient in the past, as rolling parameters can be adjusted after random measurement of the semi-finished products of a new production run. However, this manual inspection is a demanding task with some safety challenges. Therefore, we were looking for a modern solution to automate this step,” explains Thomas Hilbert from ArcelorMittal.

The resolution of the manual thickness measurement is limited to 1 mm and the product dimensions are measured only after the rolling process to check whether the rolling parameters are set correctly. In the event of deviations, adjustments cannot be made in a timely manner, which may result in damage to the rolls of the mill stands if the product exceeds the target dimensions. “We were impressed by the professionalism and attention to detail of ArcelorMittal’s R&D department for advanced sensor solutions,” recalls t Axel Hülsmann, CTO at OndoSense. “Thomas Hilbert was the first to identify our sensors for this application at the time and used his extensive knowledge of rolling process automation to efficiently implement a value-added measurement system based on our radar sensors.”

Width measurement of metal slabs with the OndoSense apex radar sensor system. © OndoSense
Width measurement of metal slabs with the OndoSense apex radar sensor system.
© OndoSense

Inline radar measurement increases productivity of the rolling mill

With the new radar sensor solution, steel slabs, billets and beams can now be measured precisely and early in the rolling process. With a high accuracy of less than one millimeter, the system is much more precise than caliper measurement. In addition, the system enables non-contact and reliable measurements of the glowing products even in the harsh environments of the steel industry with water vapor, dust, smoke or difficult lighting conditions.

For measurement, two radar distance sensors are placed on both sides of the product. The distance between the sensors can then be used to continuously measure the product dimensions regardless of the alloy of the metal products. If required, a robust heavy-duty housing actively protects the sensor from extreme temperatures.

The compact sensors are easy to integrate into production and require little maintenance. Compared to optical sensor technologies such as lidar or laser, radar is much less susceptible to interference from small particles present in dust and vapor. The key factor here is the much longer wavelength of the radar beams.

The precise measurement enables higher productivity of the plant. “If the semi-finished product has incorrect dimensions, damage can occur to the rolling lines and the end product is outside the tolerances. This leads to line downtimes, maintenance work and scrap,” says Thomas Hilbert. The new radar solution thus leads to lower energy consumption and reduced CO2 emissions.

“Radar undoubtedly has great potential when it comes to increasing efficiency and productivity in the steel industry. Using OndoSense radar technology has already helped us save a lot of time, money and material, and ultimately reduce CO2 emissions. I look forward to further projects with OndoSense to continue the journey towards more digitalized, sustainable steel production at ArcelorMittal,” says a delighted Thomas Hilbert.

Background

OndoSense realizes radar sensor technology for a digitalized industrial world. With sensor solutions based on precise, robust radar technology and smart sensor software, the Freiburg-based company supports its customers in obtaining important data for the intelligent control of production plants and machines. In this way, OndoSense is helping to drive the digital transformation in Industry 4.0. Radar sensor technology can be used in a wide variety of applications – even in challenging environments with dust, steam, smoke, fire or noise. OndoSense had been founded in 2018 by two radar experts from the Fraunhofer Institute for Applied Solid State Physics IAF.

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