Drives & Controls Magazine February 2023

measurements, several distance points are evaluated. Measurements can be made on almost any type of surface, including mirrored and glass surfaces. The technique can be used for: one-sided thickness measurement of transparent materials; two-sided measurements; or multi-layer measurements, for example involving coatings, solar cells or smartphone screens. n capacitive sensors using capaNCDTs (capacitive Non-Contact Displacement Transducers) based on plate-type capacitor principles. The sensor and the object represent two plate electrodes. If a constant alternating current flows through this “capacitor”, the amplitude of the alternating voltage on the sensor is proportional to the distance between the capacitor electrodes. The alternating current is demodulated and output, for example, as an analogue signal. Capacitive sensors can measure against any electrically conductive surface, even semiconductors and are capable of one- or two-sided thickness measurements. n 2D and 3D laser scanners produce a wide laser line on the target and can measure parameters including profiles, widths, height, depth, edge, bead, angles, roundness and more. For example, Micro- Epsilon offers laser profile scanners with built-in controllers that calculate the 2D profile of a surface from the intensity values on a CMOS sensor matrix. With some models, profile evaluation is possible directly in the sensor, allowing simple or complex measurements to be implemented in a scanner and output as measured value. These techniques are suitable for almost any diffuse material, including foodstuffs, metal, plastics, wood, silicon and rubber. They are capable of one- or two-sided measurements, as well as profile or edge measurements. n through-beam laser micrometers are used primarily as part of manufacturing processes and quality control on production lines, measuring continuous material as well as single parts. A wide beam is projected between a transmitter and receiver to create a curtain of light. Objects breaking the beam create edges or shadowed areas that are used to determine the object size or position. The technique is suitable for any material that breaks or reduces the light received and can be used to measure diameters, gaps, segments and edges. It can be used for one or two-sided measurements, as well as profile or edge measurements. n 43 www.drivesncontrols.com February 2023 SENSORS n Two-sided thickness measurements are performed using at least one pair of sensors mounted opposite each other. 2D and 3D laser scanners can be used to measure profiles, widths, heights, depth, beads, gaps, angles and roundness Laser scanners check dimensions of sheet metal in seconds Dimensionics, a German supplier of measuring and testing technologies, is using 2D/3D laser profile scanners in an automated system that tests the dimensional accuracy of sheet metal. The company’s Disionic Sheet Control measuring table uses two scanners to measure sheet metal blanks and to check them for width, length, angle, straightness, deflection (convex/concave) and the planarity of the edges. The automated testing system replaces what was previously a laborious manual process. The test process takes just a few seconds. The two laser profile scanners – Micro-Epsilon two scanControl 3000-25/BL systems – are mounted on an XY table. Each scanner has a 25mm measuring range and is guided over two edges in the X and Y direction of the sheets. The sensors use blue lasers to achieve precision and reliable results on the shiny metallic sheets. The scanners, which have built-in controls, transmit their data via Gigabit Ethernet to software for analysis. They can detect production errors such as inaccurate edges or dimensional deviations caused by inaccurate positioning. The quality of the sheet metal blanks is thus checked in a traceable and reliable manner. Dimensionics’automated sheet metal measuring system replaces a previous laborious manual process