Contact-free revolution of an
entire industry

Balluff made the actual breakthrough in sensor technology at the end of the 1960s when the company started to produce a self-developed inductive proximity switch. BES sensors are still an integral part of the product portfolio of the automation specialist. 

There must have been great disappointment at first when Eduard Hermle and his employees realized in the mid-1960s that their new development partner did not have the best of intentions toward them. After the positive experiences which his company Balluff enjoyed during the development of its first cam switch with the Nürtingen-based mechanical engineering company Heller, a partnership which still exists today, Hermle wanted to continue on the path toward automation technology. Together with another company, Balluff worked on the development of an inductive proximity switch. However, this partnership did not last long. On the contrary. Serious differences arose in regard to the reliability and sustainability of the technical specifications and promises, thus jeopardizing the company’s credibility with customers. This was alien to Hermle’s business principles and ultimately led to the company taking over sole responsibility for the new technology.

From a mechanical to an electronic switching operation

“A decision was then taken to recruit our own engineer,” remembers Rolf Hermle, the son of the company founder Eduard Hermle and Balluff managing director until the end of 2009. “We therefore co-developed this new technology from scratch and created the basis for our product portfolio in the coming years.” This “new technology” involved an inductive proximity switch which even today Balluff calls “BES”. BES stands for the Balluff Electronic Sensor. This non-contact sensor was a technological leap and represented significant progress in control technology for the mechanical engineering industry. The inductive proximity switches developed by Balluff no longer triggered switching operations mechanically, but completely contact-free via an electromagnetic pulse. Production of the first generation of the inductive proximity switch BES started in 1968. The switch was used to precisely measure distances and identify objects in the metal working sector. Anyone now visiting Balluff’s website will find just under 2,000 model versions of the BES switch in a wide range of configurations and for nearly every application area in modern automation and sensor technology.


"A decision was then taken to recruit our own engineer and further develop this technology ourselves."

Rolf Hermle, Sohn von Eduard Hermle, bis Ende 2009 geschäftsführender Gesellschafter

Switching in an electric field

Inductive sensors operate without contact and identify metal objects moving in the electromagnetic measuring field of the sensor. The switching operation can be defined precisely when connected to the machine control system. Inductive proximity switches and distance sensors with measuring accuracy down to the micrometer range are now standard technology in modern mechanical engineering. Measuring only a few centimeters, the unremarkable pins made of alloyed brass or stainless steel are used in practically every production process. They reliably record the presence, movement and position of metal objects, even under extreme mechanical and thermal conditions.

“Due to the development of the BES switch, Balluff is one of the pioneers of industrial automation in the machine tool industry,” says Gerhard Dürr with pride. At Balluff he held the positions of sales manager from 1970 to 1991 and managing director from 1991 to 1995. “Our inductive proximity switches and distance sensors revolutionized industrial production processes.” The persistence of Eduard Hermle and his then team was the reason why Balluff stayed on the ball, recognized the opportunities and gave a real boost to automation technology in mechanical engineering with the development of the BES switch.

Driving innovation

From a workshop for bicycles and sewing machines in 1921 to a sensor and automation specialist for the Industrial Internet of Things: Constantly evolving and not being content with the status quo is what sets Balluff apart.

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