Zutt M, Forster C, Lang T, Schmidt M, Bartels D (2026)
Publication Type: Journal article
Publication year: 2026
Book Volume: 143
Pages Range: 416-419
DOI: 10.1016/j.procir.2026.07.087
The electrical contacting of copper hairpins is a critical process in electric drivetrain production. However, processing copper (Cu-ETP) with standard infrared lasers is hindered by high thermal conductivity and low absorption rates of less than 5 %. Visible blue laser radiation (λ ≈ 445 nm) fundamentally overcomes these limitations by providing an intrinsically high absorption rate of approximately 45 – 65 %, representing a nearly 10-fold increase compared to the absorption rate of infrared sources. Due to these high absorption rates, the possibility of employing a low-intensity conduction mode welding strategy is enabled. This study utilizes 4 kW of blue laser power to investigate both spatter-intensive deep penetration regime and stable conduction mode by a caustic-based spot size adjustment on 6 x 6 mm² copper hairpin joints. To quantify the physical spatter ejections, an automated computer-vision algorithm was employed to analyze high-speed recordings. The results demonstrate that switching to conduction mode reduces spatter formation by approximately 90 % compared to the deep penetration regime. Metallographic analysis reveals that while deep penetration offers shorter cycle times (0.5 s), it results in increased micro-porosity. Conversely, the conduction mode (1.0 s) ensures a reduction in internal defects depending on the scan strategy. The findings prove that 4 kW of blue laser power is sufficient to reach comparable penetration depths in both regimes. This highlights a key trade-off: while deep penetration welding offers advantages for shorter cycle times, the static low-intensity conduction mode is the superior strategy for high-quality, low-defect manufacturing.
APA:
Zutt, M., Forster, C., Lang, T., Schmidt, M., & Bartels, D. (2026). Copper Hairpin Welding Utilizing a 4 kW Blue Laser: Investigating Deep Penetration and Conduction Mode for Spatter and Porosity Reduction. Procedia CIRP, 143, 416-419. https://doi.org/10.1016/j.procir.2026.07.087
MLA:
Zutt, Matthias, et al. "Copper Hairpin Welding Utilizing a 4 kW Blue Laser: Investigating Deep Penetration and Conduction Mode for Spatter and Porosity Reduction." Procedia CIRP 143 (2026): 416-419.
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