The need to manufacture components out of copper is significantly increasing, particularly in the solar technology, semiconductor, and electric vehicle sectors. In the past few decades, infrared laser (IR) and green laser (GL) have been the primary technologies used to address this demand, especially for small or thin components. However, with the increased demand for energy saving, alternative joint techniques such as blue diode laser (BDL) are being actively explored. In this paper, bead-on-plate welding experiments on 0.2 mm thick pure copper samples employing a BDL are presented. Two sets of parameters were carefully selected in this investigation, namely Cu-1: Power (P) = 200 W; Speed (s) = 1 mm/s; and angle = 0°, and Cu-2: P = 200 W; s = 5 mm/s; and angle = 10°. The results from both sets of parameters produced defect-free full penetration welds. Hardness test results indicated relatively softer weld zones compared with the base metal. Tensile test samples fractured in the weld zones. Overall, the samples welded with Cu-1 parameters showed better mechanical properties, such as strength and elongation, than those welded with the Cu-2 parameters. The tensile strength and elongation obtained from Cu-1 were marginally lower than those of the unwelded pure copper. The outcomes from this research provide an alternative welding technique that is able to produce reliable, strong, and precise joints, particularly for small and thin components, which can be very challenging to produce.

In the last decade or so, the technology in electric vehicles has advanced significantly including increased battery range, faster charging, wireless charging, battery management, battery weight reduction, power and efficiency of the electric motor, and many others. There are two main components in the electric motor, namely, rotor and stator. Hairpins are critical part of a stator. They are made of pure copper. One of the important processes in the fabrication of a stator is connecting/welding the individual hairpin. In this paper, a brief description of hairpin manufacturing based on the published articles and the results from more recent investigation, particularly the welding aspect is provided.

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.

Laser technology plays a crucial role in human lives. They are used signifi cantly in the scientifi c area, military, medical, manufacturing and even in the entertainment industry. Their usage is critical due to the advantages over many other technologies including precision and accuracy, fast and high efficiency, productivity, reproducibility, fl exibility, easy to automate, less energy consumption, more environmentally friendly which in turns more cost-effi cient. This paper provides a review of laser technology focusing on the latest technology of blue diode laser in manufacturing.

With the rise in demand for electric vehicles (EV), hairpin welding is gaining popularity for its efficient manufacturing of critical EV motor components. Due to its high electrical and thermal conductivity and relative affordability, copper is commonly used. The tip of the hairpin can be joined by laser welding, micro TIG, and resistance brazing. Of these techniques, infrared (IR) laser welding is commonly used for its high dimensional accuracy and non-contact joining. However, copper is highly reflective to IR wavelengths, limiting the speed of this technique in joining copper hairpin couples. Considering the high manufacturing volume of the EV motor industry combined with copper hairpins being a high-volume component in each EV motor, copper’s high reflectivity to IR wavelengths presents a significant challenge to EV manufacturing efficiency. To accommodate this challenge, many researchers have examined the feasibility of using blue diode lasers to produce copper hairpin welds to leverage copper’s higher absorptivity to blue light wavelengths. Alternatively, this paper investigates a hybrid approach in which both IR and blue diode lasers (BDL) are used simultaneously to benefit from the advantages of both IR and blue wavelengths. To investigate this technique, hairpins were laser spot welded using IR, and hybrid technology was also analyzed and presented. Successful welds were produced in 0.6 s with both IR-only and hybrid techniques. Using IR-only and a power of 1000 W, a shallow weld joint with a fusion zone depth ranging from 0.2 to 2.8 mm was produced. A satisfactory weld joint (weld bead) was achieved when the IR power was increased to 1300 W exhibiting a fusion zone depth of 3.0 to 3.1 mm. When the hybrid method (1000 W IR with 750 W BDL) was employed, a satisfactory weld joint was also achieved with a fusion zone depth of 2.9 to 3.0 mm. Electrical resistivity measurements of the 1300 W IR-only and hybrid methods were on the same order of magnitude as the unwelded copper reference of 1.9 × 10⁻⁴ Ω.cm. Hairpins welded with 1000 W IR resulted in higher electrical resistivities ranging from 1.2 × 10⁻³ to 6.2 × 10⁻³ Ω.cm. Peel force tests demonstrated the highest max peel force of 770 ± 15 N under the 1300 W IR condition, whereas the 1000 W IR and hybrid methods resulted in max peel forces of 410 ± 15 and 720 ± 20 N, respectively. Regarding peel test elongation at failure, the hybrid method was highest at 13 ± 3%, followed by IR with 1300 W at 12 ± 3% and IR with 1000 W at 11 ± 2%. The results of this paper demonstrate comparable microstructural, electrical, and mechanical properties under hybrid welding to higher power IR welding, simultaneously showing hybrid laser welding as a suitable alternative in copper hairpin joining for EV motor application.