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Use case · 3D Top-Hat
New beam shapes for laser welding.
Copper is one of the hardest metals to weld reliably. In an independent study, the Bayerisches Laserzentrum (BLZ) used a Midel elliptical flat-top on a 3 kW green disk laser to show what a tailored beam shape can do: a stabilised melt pool, a calmer process, and dramatically less spatter.
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Challenge
- Copper’s high thermal conductivity and low melt viscosity make the weld pool unstable
- Even with green (515 nm) radiation, spatter remains a prone defect that limits the process window
- Electric-vehicle joints must meet both mechanical and current-carrying requirements — with fewest seam imperfections
Result
- Elliptical flat-top stabilises the vapour capillary and calms the melt pool
- Up to 93% fewer spatters per 5 mm of seam (3 kW, high feed rate)
- Up to 60% fewer spatters & melt ejections at equal penetration depth — and 41% smaller particles
- Enlarged heat-conduction welding regime and an advantageous seam shape
New beam shapes, not just more power, open a wider, calmer process window for demanding materials like copper.
Setup & conditions:
Trumpf TruDisk 3022 disk laser (515 nm, up to 3 kW cw) on a Kuka KR30 robot; Cu-ETP copper, feed rate 2–20 m/min, nitrogen shielding. The elliptical beam is formed by an all-reflective DOE from Midel Photonics (measured reflection efficiency > 99%), compared against a reference top-hat setup. Independent study by the Bayerisches Laserzentrum (BLZ) and FAU Erlangen-Nürnberg.
Full study: Kaufmann, Roth & Schmidt, “Tailored laser beam shapes for welding of copper using green laser radiation,” Int. J. Adv. Manuf. Technol. 136, 3843–3862 (2025) — doi.org/10.1007/s00170-024-13180-z.
Full study: Kaufmann, Roth & Schmidt, “Tailored laser beam shapes for welding of copper using green laser radiation,” Int. J. Adv. Manuf. Technol. 136, 3843–3862 (2025) — doi.org/10.1007/s00170-024-13180-z.
Setup — a green high-power beam folded through the beam shaper onto the copper seam
Result — with beam shaper (Δm = 1.9 mg) vs. without (Δm = 39.6 mg): weld bead (top) and process (bottom)
Result — with beam shaper (Δm = 1.9 mg) vs. without (Δm = 39.6 mg): weld bead (top) and process (bottom)
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