Additive manufacturing of integrated actuators and sensors.

Additive manufacturing, functional integration, multi-material printing

Experimental fused filament fabrication (FFF) multi-material printer at Fraunhofer LBF with printed sensor prototypes.

The amount of components of complex, customized assemblies can be greatly reduced with additive manufacturing, and many functions can be integrated directly into a component. This simplifies the manufacturing process and reduces the necessary assembly space. In order to exploit these advantages for mechatronic systems as well, scientists at Fraunhofer LBF are researching additive manufacturing of integrated actuators and sensors. They can be used in lightweight structures to reduce interfering or damaging vibrations as well as for structural monitoring.

Multi-material printing with fused filament fabrication (FFF)

Several materials are needed for the additive production of prototypical mechatronic systems in order to be able to dispense as much as possible with the insertion or bonding of purchased actuator and sensor technology. Fused filament fabrication (FFF) printers are particularly suitable for this because they require low investment costs and offer high flexibility in the type of materials to be processed. With multiple different print heads on one printer, Fraunhofer LBF can print plastic filaments as well as pastes, which can also be cured under UV light. In addition to standard thermoplastics such as ABS or PP, it is also possible to use functional materials such as electrically conductive or soft magnetic materials or even shape-memory polymers.

Integration of actuators for vibration control

As part of the OpenAdaptronik project, an immersion coil actuator was designed and manufactured using the FFF printer. The actuator was designed for multi-axial vibration reduction on the camera of a quadrocopter. A ferromagnetic filament was used in addition to ABS for the coil carrier with integrated spring to guide the magnetic flux in the actuator housing. The necessary magnet was inserted during the printing process and printed inside the housing. The measurements on the finished actuator demonstrated that forces can be generated with the additively manufactured actuator that are comparable to commercially available actuators of the same size. Although the material has low magnetic permeability, the assembly space can be optimally designed.

Multi-part additive-manufactured voice coil actuators (aka voice coil actuators).

Integration of sensors for structural condition monitoring

Moreover, the possibility of integrating sensory functions into components using additive manufacturing was researched. The objective was structural state monitoring in autonomous aircraft. Various electrically conductive plastic filaments were examined and compared for this purpose. Subsequently, prototype-resistive strain gauges and capacitive force and acceleration sensors could be manufactured additively. New materials with higher electrical conductivity will further enhance sensor sensitivity in future applications.

Applied additively manufactured strain gauge.

Great potential for additive manufacturing of mechatronic systems

Additive manufacturing thus offers multiple benefits for mechatronic systems:

  • Sensors can be integrated at critical points that were previously inaccessible, which particularly benefits light-weight-optimized structural components.
  • Actuators can be customized in terms of strength and assembly space so that there is no need for oversized actuators.Material use and power consumption are reduced to the bare minimum.
  • Electrically conductive materials make external lines for signal routing and corresponding soldering obsolete. This facilitates the production of compact, functionally integrated systems with low assembly costs.
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Funded by the Federal Ministry of Education and Research