Electricity and Control February 2021

SENSORS + SWITCHES

Sensors support traditional crispbread production in Sweden What is the most typical Swedish product? It does not take long to answer: crispbread. Sweden’s largest producer of the traditional round crispbread is based in the small town of Leksand in central Sweden. In this application report, ifm explains how sensors are used to support the smooth running of the automated production process.

T he company Leksands Knäckebröd was founded in 1920 and has been family-owned since then, to- day in the 4 th generation. While the recipes are still the same after about 100 years, the production process is now completely different. Production is automated with the latest state-of-the-art technology. To ensure the systems always run smoothly, different sensors monitor the produc- tion process – from the supply of the ingredients to the dispatch area. Peter Joon, Managing Director at Leksands Knäckebröd, says, “We use many different sensors as this is a modern, highly automated production process. To maintain the high productivity of 99.6%, we need sensors we can trust. For this reason we are now using many sensors from ifm. They are of good quality and function well with our systems.” Lars Ohlner, Automation Engineer at Leksands Knäckebröd, adds, “We use products from ifm because they are easy to configure and they are cost-effective; they simply function reliably. We mainly use photoelectric and capacitive sensors and some flow sensors. We obtain high- grade and effective automation and a reliable production process.” Some examples of the particularly innovative applica- tions of sensors are outlined below.

Capacitive sensors detect the flour through the walls of the pipes.

Capacitive sensors The main ingredients of crispbread are rye meal and finely ground rye and wheat flour. They are supplied to the mixing tools via various pipes. Capacitive sensors monitor the sup- ply at the pipes or the level in the temporary storage tanks. Capacitive sensors are distinguished by detecting differ- ent materials, even through the tank wall, unless that is of metal. If a pipe is no longer completely filled with flour, the capacitive sensor detects this state and sends a switching signal to the controller. Often, several capacitive sensors are used on storage tanks or silos: at the top, for example, to signal a possible overflow in good time, or at the bottom of the silo to signal a critical empty state. Potentiometers are used to adjust the sensors after in- stallation. The switch point is adjusted depending on the wall thickness of the pipe and the type of medium to be de- tected. The new KI6000 sensors from ifm need to be set es- pecially precisely. The 12-point LED signal display makes it much easier for the user to set the optimum switch point, which is in the centre of the display. The green LEDs on either side of the switch point indicate its reliability. Depos- its, material changes and suchlike are displayed directly on the sensor and the user can readjust the switch point as needed. That means an imminent error can be detected in good time and avoided. If help is needed with the effects of process changes, this is much easier to explain and rectify with the clear switch-point visualisation. By phone the user can describe

100 years of Swedish tradition: the Leksands crispbread follows the distinctive traditional form – round with a hole in the middle.

18 Electricity + Control FEBRUARY 2021

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