With a laser structuring process, scientists of the Laser Micromachining Group at the Laser Zentrum Hannover e.V. (LZH) have developed a new technique for the manufacturing of integrated sensors. With these sensors, even smallest strains in the parts of a machine tool that are difficult to deform can be made visible. Thus, for example the condition of the machine can be monitored during the ongoing process, process forces and vibrations can be measured and this information can be used for the monitoring and process optimization.
Machine tools have a particularly stiff design, therefore the process forces only cause small deformations. However, to ensure precise measurements, strain sensors are deposited in the notches of a machine part. Under load, a strain elevation occurs around the notch, and thus the strain sensor provides a particularly strong measurement signal. Up to now, there was no suitable method available to deposit sensors in structures that are so difficult to access and so complex. Alternative approaches, such as photo-lithographically generated sensors, can only be used for planar surfaces, and glued thin-film strain sensor are not suited for these harsh operating conditions.
After being coated with an insulating and a sensor layer, the structures of the integrated sensors are written directly on the part using an ultrashort pulse laser with a lateral resolution of 10 to 100 µm. Here, a laser scanner ensures a very fast structuring process. Conventional mask processes are no longer needed, making the manufacturing of these high-quality thin-film sensors economically attractive even for small and medium quantities. First prototypes of the laser-structured sensors developed at the LZH were already integrated into the Z axis slide of a machine tool within the course of the Collaborative Research Centre (SFB) 653 "Gentelligent Components in Their Lifecycle". In endurance tests, the sensors indicated even smallest deformations of only 0.001 %.