Electrical resistivity of additively manufactured AlSi10Mg for use in electric motors

Abstract

Additive manufacturing (AM) opens up a design freedom beyond the limits of traditional manufacturing techniques. Electrical windings created through AM could lead to more powerful and compact electric motors, but only if the electrical properties of the AM printed part can be shown to be similar to conventionally manufactured systems. Until now, no study has reported on the suitability of AM parts for electrical applications as there are few appropriate materials available to AM for this purpose. AlSi10Mg is a relatively good electrical conductor that does not have the same reported issues associated with processing pure aluminium or copper via selective laser melting (SLM). Here, experiments were conducted to test the effects of geometry and heat treatments on the resistivity of AlSi10Mg processed by SLM. It was found that post heat treatments resulted in a resistivity that was 33% lower than the as-built material. The heat treatment also eliminated variance in the resistivity of as-built parts due to initial build orientation. By conducting these tests, it was found that, with this material, there is no penalty in terms of higher resistivity for using AM in electrical applications, thus allowing more design freedom in future electrical applications.

Electrical Resistivity of Additively Manufactured Silicon Steel for Electrical Machine Fabrication

“…As the samples with 3% silicone content exhibited isotropic properties of electrical resistivity, it can be assumed that electrical steel does not experience anisotropic crystal structure during selective laser melting with employed printing parameters. Some authors [9] have experienced anisotropic electrical properties when printing samples from AlSi10Mg, which was caused due to melted microstructure of the printed samples. The authors measured lowest resistivities in the build direction, due to needle-like shapes of aluminum solidified in the build direction.…”

“…These defects have been shown to have a significant effect on the mechanical [8], electrical [9] and magnetic properties [10] of the SLM fabricated material. Additional silicon content in steel results in increased electrical resistivity and magnetic permeability of the material, however as a trade-off, reducing its printability due to decreased ductility and thermal conductivity.…”

Additive Manufacturing of Shaped Profile Windings for Minimal AC Loss in Electrical Machines

“…Once the part is complete, excess powder is removed and recycled before the part is separated from the metallic build platform using Electro Discharge Machining (EDM). The process parameters, such as layer thickness, applied power and build orientation along with post-processing steps, such as heat treating, dictate the surface finish, density and material properties of the part, [20]. MS/m, [31].…”

Additive Manufacturing in Construction of Electrical Machines – A Review

“…The winding/coil manufacture is governed by the same rules. In [42] the authors assess different material post processing/heat treatment techniques and their influence on mechanical and electrical properties of conductors fabricated with aluminium alloy AlSi10Mg. The experimental data illustrate that AM introduce inherent material anisotropy to the fabricated parts.…”