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

Abstract

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 have been difficult or impossible to manufacture previously. This work combines these two powerful methods to design and manufacture permanent magnetic system with specific properties. The topology optimization framework is simple, fast, and accurate. It can be also used for reverse engineering of permanent magnets in order to find the topology from field measurements. Furthermore, a magnetic system that generate 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 system show a very good agreement.

3D printed magnets for neutron spin manipulation

“…A maximum printing temperature of 260 • C, and a nozzle diameter of 0.4 mm are used. Structures with layer heights between 0.05 and 0.3 mm are printable with our setup, allowing us to manufacture polymerbonded rare-earth magnets with complex shapes [6]. Figure 2 shows a photograph of the printer and a scanning electron microscope (SEM) image of a filament.…”

“…Shapes for spin flipper magnets were designed with the help of FEM methods, including in particular an inverse stray field computation and topology optimization [5,6]. This work uses a density method with the material distribution ρ as a variable to solve the topology optimization.…”

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

“…The size of the extended mesh is chosen to be approximately 5 times larger than the original mesh in each spatial dimension and we apply zero Dirichlet boundary conditions on the outer boundary. This so-called truncation approach was already shown to provide good results for topology optimization in [17]. We solve the stray-field potential u by the weak formulation…”

Computational study on microstructure evolution and magnetic property of laser additively manufactured magnetic materials

“…Electron beam melting (EBM) is also tried to produce MnAl(C) magnets [27]. Apart from the SLM and EBM based AM technique, other 3D printing technologies without high energy input and high temperature, such as binder jetting and material extrusion, are recently applied to the production of polymer-bonded magnets [28][29][30][31][32]. These experimental studies reveal the notable effect of AM process on the microstructure and magnetic properties of magnetic materials, and provide insight into the challenges for the design and control of magnetic properties by AM.…”