Christian Huber

3D print of polymer bonded rare-earth magnets, and 3D magnetic field scanning with an end-user 3D printer

3D print is a recently developed technique, for single-unit production, and for structures that have been impossible to build previously. The current work presents a method to 3D print polymer bonded isotropic hard magnets with a low-cost, end-user 3D printer. Commercially available isotropic NdFeB powder inside a PA11 matrix is characterized, and prepared for the printing process. An example of a printed magnet with a complex shape that was designed to generate a specific stray field is presented, and compared with finite element simulation solving the macroscopic Maxwell equations. For magnetic characterization, and comparing 3D printed structures with injection molded parts, hysteresis measurements are performed. To measure the stray field outside the magnet, the printer is upgraded to a 3D magnetic flux density measurement system. To skip an elaborate adjusting of the sensor, a simulation is used to calibrate the angles, sensitivity, and the offset of the sensor. With this setup, a measurement resolut...

3D Printing of Polymer-Bonded Rare-Earth Magnets With a Variable Magnetic Compound Fraction for a Predefined Stray Field

Additive manufacturing of polymer-bonded magnets is a recently developed technique, for single-unit production, and for structures that have been impossible to manufacture previously. Also, new possibilities to create a specific stray field around the magnet are triggered. The current work presents a method to 3D print polymer-bonded magnets with a variable magnetic compound fraction distribution. This means the saturation magnetization can be adjusted during the printing process to obtain a required external field of the manufactured magnets. A low-cost, end-user 3D printer with a mixing extruder is used to mix permanent magnetic filaments with pure polyamide (PA12) filaments. The magnetic filaments are compounded, extruded, and characterized for the printing process. To deduce the quality of the manufactured magnets with a variable magnetic compound fraction, an inverse stray field framework is developed. The effectiveness of the printing process and the simulation method is shown. It can also be used to manufacture magnets that produce a predefined stray field in a given region. This opens new possibilities for magnetic sensor applications. This setup and simulation framework allows the design and manufacturing of polymer-bonded permanent magnets, which are impossible to create with conventional methods.

Topology optimized and 3D printed polymer-bonded permanent magnets for a predefined external field

Topology optimization offers great opportunities to design permanent magnetic systems that have specific external field characteristics. Additive manufacturing of polymer-bonded magnets with an end-user 3D printer can be used to manufacture permanent magnets with structures that had been difficult or impossible to manufacture previously. This work combines these two powerful methods to design and manufacture permanent magnetic systems with specific properties. The topology optimization framework is simple, fast, and accurate. It can also be used for the reverse engineering of permanent magnets in order to find the topology from field measurements. Furthermore, a magnetic system that generates a linear external field above the magnet is presented. With a volume constraint, the amount of magnetic material can be minimized without losing performance. Simulations and measurements of the printed systems show very good agreement.

Interlaminar Magnetic Flux Assessment of a Transformer Core Measured by an Extra-Thin Printed Foil Detector

Transformer cores represent complex 3-D magnetization systems with balancing off-plane fluxes, normal to magnetization plane. Therefore, for optimizations of core performance, not only the information about the local induction distributions in the plane, but also perpendicular to it is highly essential. The conventional sensors for detections of off-plane inductions <inline-formula> <tex-math notation=LaTeX>

Passive wireless strain measurement based upon the Villari effect and giant magnetoresistance

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3D-printed phase waveplates for THz beam shaping

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A fast finite-difference algorithm for topology optimization of permanent magnets

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Contactless and absolute linear displacement detection based upon 3D printed magnets combined with passive radio-frequency identification

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Simulation of layer measurement with confocal micro-XRF

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Topologically Protected Vortex Structures to Realize Low-Noise Magnetic Sensors

</tex-math></inline-formula>), reusable foil detector with handles for easy and precise insertion and positioning in the interior of a laminated core. The detector was assembled by a low-cost 3-D printer, equipped with a micro-dispersing system for printing of conductive ink, controlled by in-house developed software. The manufactured foil sensor, due to its high mechanical stability, enables detections of off-plane flux at many different locations within an entire core. The detector was effectively tested in a three-phase model transformer core, stacked from three packages of different width. The results prove the important role of sensor thickness for precise detection of off-plane induction. Peak induction <inline-formula> <tex-math notation=LaTeX>