Current devices for measuring surface hardness feature a displacement sensor integrated separately into the machine to determine the distance traveled when penetrating the body to be tested. As a result, the hardness testing machines have a very rigid design, are extremely expensive and can only measure small components. In the recently launched “NanoSense” research project, a new measuring head is being developed for flexible integration into universal testing machines and XY-axis manipulators. For the first time, sensors for force and displacement measurement are combined as novel elements and integrated into the testing machine. This eliminates the need for a rigid and expensive machine frame.
For the first time, the new sensor unit enables a force resolution of up to 5 µN with a displacement resolution of 100 picometers. It allows precise, quasi-destructive testing of any material, including extremely thin layers. Thanks to the modular connection of the measuring head to common universal testing machines, the combined force-displacement sensor can measure hardness on components of any size and in any position.
A two-stage drive concept with piezo stack actuators and the electronics for evaluating and processing the sensor signals are also the subject of developments with partners from industry. Calibration is performed using an innovative auto-calibration process based on silicon leaf springs.
The research and development work in the project “Development of a hardness measuring head based on a novel combined force-displacement sensor with a resolution of 100 pm for determining the hardness of surfaces in the nanometer range” (NanoSense) was funded by the German Federal Ministry for Economic Affairs and Energy.
Funding code: KK5085702SN0
