Researchers from Tallinn University of Technology and the Estonian University of Life Sciences are trying to use 3D printing to produce soft magnetic cores.


The magnetic core is a sheet of magnetic material with high magnetic permeability. They are commonly used for field guidance in a variety of electrical systems and machines, including electromagnets, transformers, motors, generators, inductors and other magnetic components.


So far, the 3D printing of magnetic cores has been a challenge due to the difficulty of maintaining the efficiency of the magnetic core. The research team has now proposed a comprehensive laser-based additive manufacturing workflow that they say can produce products with superior magnetic properties to soft magnetic composite materials.


3D printing electromagnetic materials

Additive manufacturing of metals with electromagnetic properties is an emerging field of research. The motor R&D team is developing and integrating its own 3D printed components and applying them to the system, design freedom is one of the keys to innovation. For example, 3D printing functionally complex parts with magnetic and electrical properties could pave the way for custom embedded motors, actuators, circuits and gearboxes. Such machines can be produced in digital manufacturing facilities, requiring less assembly, post-processing, etc., since many parts are 3D printed.


But due to various reasons, the vision of 3D printing large and complex motor parts has not been realized. Mainly because there are certain challenging requirements to be met on the device side, such as small air gaps for increased power density, not to mention issues with multi-material components.


So far, research has focused on "basic" components such as 3D printed soft-magnetic rotors, copper coils and alumina heat spreaders. Of course, the soft magnetic core is also one of the key points, but the most important obstacle to be solved in the 3D printing process is how to minimize the loss of the magnetic core.


A set of printed sample cubes demonstrating the effect of laser power and printing speed on the magnetic core structure. Photo via Tallinn University of Technology.


Optimized 3D printing workflow

To demonstrate the optimized 3D printed magnetic core workflow, the researchers determined the optimal process parameters for the application, including laser power, scan speed, hatch spacing, and layer thickness.


The team also investigated the effect of annealing parameters to achieve the smallest DC loss, quasi-static, hysteresis loss, and highest magnetic permeability. The best annealing temperature is determined to be 1200°C, the highest relative density is 99.86%, the lowest surface roughness is 0.041mm, the minimum hysteresis loss is 0.8W/kg, and the ultimate yield strength is 420MPa.


Ultimately, the researchers confirmed that laser-based metal additive manufacturing is a viable method for 3D printing magnetic core materials that can be applied to electric motors. In future research work, the team intends to characterize the microstructure of the part to understand grain size and grain orientation, and their effect on magnetic permeability and strength. The researchers will also further investigate ways to optimize the geometry of the core for 3D printing to improve performance.


Effect of Energy Input on Surface Roughness of 3D Printed Magnetic Core

The combination of 3D printing and magnetism inspires a range of new applications, not just electric motors. Earlier this year, an international team of scientists led by Cambridge University's Cavendish Laboratory used 3D printing to develop a set of tiny nanomagnets. The nanomagnet, which is shaped like a DNA double helix using a custom 3D printing process, shows promise in areas such as particle trapping, imaging technology and smart materials.


Elsewhere, researchers at the IMDEA Nanoscience Institute, an interdisciplinary research center in Spain, recently developed a new method for 3D printing magnets from recycled materials. The work was done to address supply chain issues during the global pandemic and the lack of manufacturing materials, including those needed to make magnets.


Amorphous 3D printing technology can realize more free processing and manufacture almost any shape, which has great market prospects.


We know that one of the biggest bottlenecks in the development of amorphous motors is the processing efficiency of the iron core. Scientists' attempts, 3D printing is expected to solve this problem, and will definitely boost the industrialization of amorphous motors.



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