3D printing integrates actuators and sensors into complex components
Based on the results of their research projects, the scientists at Fraunhofer LBF see great potential for the manufacture of mechatronic systems using 3D printing: “Additive manufacturing offers multiple benefits. Sensors can be integrated at critical points that were previously inaccessible. In particular, lightweight structural components can benefit from this,” explains Dr. Torsten Bartel, who headed the various projects at Fraunhofer LBF.
In addition, actuators can be individualized in force and installation space in such a way that oversized actuators do not have to be used. This limits the use of materials and electricity to the bare essentials. “After all, electrically conductive materials make it possible to dispense with external signal lines and the corresponding soldering work. In this way, compact, function-integrated systems can be manufactured with minimal assembly effort,” emphasizes Bartel.
Several materials are required for the additive manufacture of prototypical mechatronic systems in order to be able to dispense as far as possible with the insertion or bonding of purchased actuators and sensors. Fused filament fabrication (FFF) printers are particularly suitable for this purpose. They are comparatively inexpensive and very flexible in the choice of materials to be processed.
With this device, the scientists at Fraunhofer LBF can print various plastic filaments in one pass thanks to several different print heads. In addition to standard thermoplastics such as ABS or PP, functional materials such as electrically conductive or soft magnetic materials and shape memory polymers are also used. The object of development is currently to print electrically conductive or piezoelectrically effective pastes that are cured under UV light using the same printer. The aim is to master a large number of functional materials in additive manufacturing in order to be able to implement fully structure-integrated functional components.
As part of the Open Adaptronics project, the Darmstadt researchers developed a moving coil actuator, which they then produced using the FFF printer. The actuator was designed for multi-axial vibration reduction on the camera of a quadrocopter. In addition to ABS for the coil carrier with integrated spring, the scientists used a ferromagnetic filament to guide the magnetic flux in the actuator housing. The necessary magnet was inserted during the printing process and printed into the housing. “Our measurements on the finished actuator have shown that it can generate forces comparable to those generated by commercially available actuators of the same size,” says Bartel.
In addition, the LBF scientists investigated the possibility of integrating sensory functions into components with the aid of additive manufacturing. The aim was to monitor the structural state in autonomous aircraft. For this purpose, various electrically conductive plastic filaments were investigated and compared. Subsequently, the scientists succeeded in producing prototypical strain gages and force and acceleration sensors in 3D printing. By using new materials with a higher electrical conductivity, the Darmstadt researchers want to further improve the sensitivity of the sensors in future applications.
Images (C) Fraunhofer LBF