The conventional design of joints and hinges is conceivably simple, since only geometric and kinematic considerations of inherently rigid bodies and their relative motion are relevant. Loads, stresses and strain relationships are only considered in the parametric dimensioning of the overall design. Nevertheless, these designs are always associated with suboptimal frictional play and wear, multi-part construction and
corresponding assembly efforts, as well as the usually very costly effort of subtractive CNC fine machining.
In TRUMPF's challenging case, the design of a solid-state hinge, which is more complex, eliminates all of the aforementioned suboptimal characteristics. The solid-state hinge, 3D-printed in this case, is screwed onto a plane of an optic of a laser guide and connected to the thread of a motor spindle with a clamp. If the spindle now moves, the solid-state joint moves and the connected plane (i.e. the optic) moves with it. A
closer look reveals that the webs of the solid-state hinge are spring-loaded and absorb the imbalances and movements of the spindle, resulting in smooth and even motor running and travel. Due to the high demands on accuracy and reproducibility, conventional hinge systems are reaching their limits. TRUMPF has
therefore already ventured the step toward compliant systems (solid-state hinges) and tested the first components with a 17-4 PH material. But here, too, the limited performance of the base material led to long alignment times, high motor currents and an associated high load on the drive. Due to the high energy and good thermal conductivity of the metallic material, the components heated up strongly and an accurate, controllable and synchronized motion sequence could not be guaranteed.
In this case study, the potential of flexible and compliant systems in mechanical engineering and their technological advantage through the use of amorphous metals in 3D printing are examined in more detail using the machine element of a solid-state hinge itself and the success story of the TRUMPF company.