Comparison of the Physical Performance between Infrared and Hybrid Welding of Copper Wire Hairpins

Abstract With the rise in demand for electric vehicles, hairpin welding is gaining popularity for its efficient manufacturing of critical EV motor components. Due to its high thermal conductivity, copper is commonly used. The tip of the hairpin can be joined by laser welding, micro TIG, and resistance brazing. In this paper, hairpin welding using infrared and hybrid (infrared combined with blue diode laser) technology is presented. When using infrared-only with a power of 1000 W, a shallow weld joint was produced. A decent weld join (weld bead) was achieved when the power of the infrared was increased to 1300 W. However, when the hybrid method was employed with an infrared power of 1000 W and blue diode laser power of 750 W, a very satisfactory weld joint was achieved, i.e., comparable to that of infrared only with a power of 1300 W. The electrical resistivity results indicated relatively low resistivity of the welded hairpin samples. Peel test results also suggest that high force is required to break the decent weld joints, especially the samples welded with IR 1300 W and the hybrid method. The results showed that hybrid laser technology is very promising for hairpin welding.