BFI Shapemeter Roll
The BFI flatness measuring roller is one of BFI's world-leading successful products and a proven measuring instrument for the production of metal strips in modern cold rolling processes. Since its first introduction in 1976, it has been continuously developed to meet increasing customer requirements. With over 40 years of experience in development, more than 2,000 rolls sold worldwide and use in over 57 countries, the BFI flatness measuring roll sets standards in the precise measurement of strip flatness in the industry.
The generations of the BFI Shapemeter Rolls
The development of the BFI flatness measuring roller includes several important milestones. It all began in 1976 with the disc type, which was the first generation to bring fundamental BFI flatness measuring technology to rolling mills. This was followed in 1991 by the pocket type, which set new standards with its high sensitivity. In 2002, the axial type was introduced, which, in addition to its high sensitivity, has a closed roller surface that ensures that no marks are left on the metal strip. The latest generation, the multi-measuring type, will be available from 2026. In addition to high sensitivity and a closed roller surface, it not only enables flatness measurement, but also the monitoring of other key process parameters, such as strip edge detection.
How the BFI Shapemeter Roll works
The BFI flatness measuring roller measures the flatness of metal strips in the cold rolling process – a decisive quality feature for strip materials such as steel, copper, aluminium or zinc. Simply put, a strip is considered flat if it lies evenly on a flat surface. Flatness defects such as waves or bulges are undesirable as they affect the quality and further processing of the material. However, such flatness defects are not visible under tension. They are caused by different fibre lengths across the strip width. Strip tension is applied during the rolling process, which stretches the fibres to the same length, resulting in longitudinal tension. This results in differences in tension across the width of the strip.
Explanation video about flatness and the functionality of the BFI Shapemeter Roll
As the metal strip is guided over the flatness measuring roller, the longitudinal tension is converted into radial forces. Areas with high longitudinal tension exert greater pressure on the roller, resulting in higher radial forces. If the longitudinal tension is lower, the pressure is correspondingly lower. These forces are measured across the entire strip width by high-precision force sensors, which are known for their high sensitivity and do not require an external power source. The BFI flatness measuring roller therefore provides precise data on the radial forces online and with high precision during the rolling process – even at high rolling speeds.
The measured radial forces are converted into flatness values using the geometric parameters of the belt and roller. These values are compared in real time with the specified target flatness curve. Depending on the deviations detected, the rolls are adjusted by bending, tilting, or selective cooling to correct the flatness and achieve the desired flatness and specifications.
Since the BFI flatness measuring roller is positioned at the exit of the roll stand, as close as possible to the roll gap (also as a deflection roller), can be carried out based on the measurements with minimal delay.
The connection electronics of the BFI flatness measuring roller, which was developed by BFI-Betriebstechnik (BFI-BT), includes components such as the rotary transmitter and the SIKO unit. The rotary transmitter enables the interference-free optical transmission of signals from the rotating roller to the stationary electronics. The SIKO unit processes these signals, converts them into digital data and ensures that the information can be passed on to the process control system in real time.
Technical specifications
The BFI flatness measuring roller can be adapted to the diverse requirements of modern rolling mills. With a variable roll diameter and length, it can be flexibly inserted into different rolling stands. The surface of the roller can be made of steel, tungsten carbide, plastic or chrome, as required, to ensure optimum protection and performance. Its high measuring accuracy ensures that the flatness of the rolled material always remains at the highest level. Additionally, the robust roller requires little maintenance. If maintenance is nevertheless required, the surface can be easily reground and recoated. The sensors can also be replaced at any time.
Areas of application
The BFI flatness measuring roller is used in a wide range of applications, including
- Steel and stainless steel production (incl. electrical steel)
- Aluminium and copper processing
- Speciality metals (incl. nickel, titanium and zinc)
- Automotive industry
- Aerospace industry
It is crucial for ensuring the high flatness of rolled products in these sectors.
Licensees: Global commitment to the highest quality
Worldwide, six licensees rely on the BFI flatness measuring roll and distribute it globally. These partners have contributed to the sale of more than 2,000 rolls in various industries and regions. Thanks to these collaborations, the BFI flatness measuring roll is now the world market leader in the field of flatness measurement.
Advantages of the BFI Shapemeter Roll
The BFI flatness measuring roller offers numerous advantages that make it the preferred choice in the cold rolling industry. Thanks to decades of further development and state-of-the-art technology, it ensures the highest precision and reliability.
Below is an overview of the key benefits:
- High measuring accuracy (1.0 I-units)
- Robust, solid roller body with closed surface to prevent marks on the strip
- Suitable for deflection roller positions with high wrap angles
- Sensors measure both flatness and strip edge position as well as strip width
- Optional integration of temperature sensors
- Optimized surface coatings tailored to strip materials
- Low maintenance requirements, compatible with all materials and tensions
- Easy retrofitting in existing rolling mills with customisable dimensions
- Flexible zone segmentation
- Compact, easily configurable electronics with simple calibration
The new generation of flatness Shapemeter Roll
The new generation of the BFI flatness measuring roller is being developed though close collaboration between the teams at ANDRITZ Metals Germany and the BFI. It marks a significant advance in flatness measurement and sets a new standard. The market launch is planned for 2026. This generation is characterised by high sensor sensitivity, a closed roller surface and state-of-the-art coating technologies and algorithms.
Additionally, further process parameters will be gradually integrated, starting with strip edge detection and temperature measurement. The integration of these parameters into the robust flatness measuring roller eliminates the need for additional measuring devices and optimises the flatness measurement. As a result, advanced process optimization is achieved, and flatness quality is sustainably improved.
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