Fraunhofer: New sensor monitors hole puncher

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Fifty punches crash onto the sheet metal of the car body and punch small holes into it that will later be used for mounting other components. But if any holes are missing it can be costly, as the component either has to be scrapped or reworked. The result is downtime.

Researchers at the Fraunhofer Institute for Surface Engineering and Thin Films in Braunschweig, Germany, have developed ultra-small sensors for continuously monitors the punching of holes in sheet metal in the car industry.

If holes are missed or the tools are too blunt to make a clean cut the sensor registers it, allowing machine operators to deal with the problem and replace blunt tools before they break or the material is damaged.

The sensors just 2 millimetres thick and have a diameter of only 20 to 25 millimetres, which is 10 per cent of the size of commercially available sensors. So they are also suitable for use in large machine tools where many punches are mounted close together and conventional sensors would be too bulky.

“Also, because of the low costs involved, you can afford to monitor every punch in a large machine,” explains Martin Weber, project manager at the institute. “When our sensors are in mass production, they will be up to 90 per cent cheaper than models which are currently available.”

The researchers and colleagues at the Fraunhofer Institute for Machine Tools and Forming Technology IWU have already tested prototypes of the sensors, with satisfactory results. Now they are optimising the technology still further so that it can be reliably mass-produced. The sensors will be on show at the Hannover Messe (Hall 6, Stand C2) which runs from 16 to 20 April.