Electrical Conductivity of Additively Manufactured Copper and Silver for Electrical Winding Applications

Efficient and power-dense electrical machines are critical in driving the next generation of green energy technologies for many industries including automotive, aerospace and energy. However, one of the primary requirements to enable this is the fabrication of compact custom windings with optimised materials and geometries. Electrical machine windings rely on highly electrically conductive materials, and therefore, the Additive Manufacturing (AM) of custom copper (Cu) and silver (Ag) windings offers opportunities to simultaneously improve efficiency through optimised materials, custom geometries and topology and thermal management through integrated cooling strategies. Laser Powder Bed Fusion (L-PBF) is the most mature AM technology for metals, however, laser processing highly reflective and conductive metals such as Cu and Ag is highly challenging due to insufficient energy absorption. In this regard, this study details the 400 W L-PBF processing of high-purity Cu, Ag and Cu-Ag alloys and the resultant electrical conductivity performance. Six Cu and Ag material variants are investigated in four comparative studies characterising the influence of material composition, powder recoating, laser exposure and electropolishing. The highest density and electrical conductivity achieved was 88% and 73% IACS, respectively. To aid in the application of electrical insulation coatings, electropolishing parameters are established to improve surface roughness. Finally, proof-of-concept electrical machine coils are fabricated, highlighting the potential for 400 W L-PBF processing of Cu and Ag, extending the current state of the art.

Automated summary

Efficient and power-dense electrical machines are crucial for driving the next generation of green energy technologies. This study focuses on the Additive Manufacturing (AM) of custom copper (Cu) and silver (Ag) windings, aiming to improve efficiency through optimized materials and geometries. The study utilizes Laser Powder Bed Fusion (L-PBF) technology to process high-purity Cu, Ag, and Cu-Ag alloys, and investigates their electrical conductivity performance. Proof-of-concept electrical machine coils are successfully fabricated using 400 W L-PBF processing, indicating the potential for this technology in advancing the current state of the art.