Post by Tjalling de Boer

🚗⚡️#AutoEnergy Mondays at Coherent Corp. 🔦 Core–ring beam shaping: weld-window control you can see (X-ray proof) High-speed laser welding rarely fails from “not enough power.” It fails from keyhole/capillary instability → vapor friction → spatter → underfill — especially when you push line speed. ⚙️💨✨ This Feb 2026 Optics & Laser Technology paper makes the mechanism tangible: the team used synchrotron X-ray imaging to watch the capillary live while tuning core vs ring power on a Coherent HighLight FL 4000CSM-ARM core–ring source. 🧭 The authors’ core message (useful for setting robust weld windows) Core + ring gives you two operating regimes — and you want to pick yours deliberately. 🎛️ 1) 🧯 Ring below capillary threshold → “thermal assist” regime The ring can’t form its own keyhole, so it acts as pre- and post-heating assist to the core. 🔥➕🔥 ✅ Result: a broader top melt pool and lower spatter at both low and high speeds. 📉✨ 2) 🌀 Ring above capillary threshold → “two-capillary / double-weld” regime At sufficiently high ring power density, core and ring form their own capillaries. As speed increases, the capillaries can progressively separate along the welding direction and behave more independently. ➿➿ 👀 The paper reports showing this separation for the first time using synchrotron X-ray imaging. 🩻✅ 🏭 Why this matters for production (EV/battery included) Beam shaping here is a process control knob — not “more power = better.” 🎚️ It lets you target: 🧩 stability via thermal assist, or 🔬 a different capillary topology that changes the physics. ⚠️ Tradeoffs they call out (worth repeating) 🟡 Ring-only at high speed can reduce spatter (capillary rear wall tilts → altered vapor friction), but it needs high power and has low joining efficiency. ⚡️⬆️📉 🔵 Core + ring can require more total power than a single focused beam for the same depth/speed — so the next step isn’t brute-force watts, it’s optimizing core–ring dimensions + power split. 🧠🎯 🔭 Outlook Next steps are exactly what process engineers want: 🔍 metallography (grain sizes in weld/HAZ) 🧪 tensile tests linking capillary geometry → properties 📐 an analytical threshold for secondary-capillary formation 🌬️ how capillary geometry steers vapor flow and spatter 👥 Contributing institutes IFSW - Institut für Strahlwerkzeuge, Production Technology Group, Technische Universität Ilmenau Fraunhofer ILT RWTH Aachen University Helmholtz-Zentrum Hereon University of Stuttgart Felix Zaiß https://lnkd.in/exSx_qdt #LaserWelding #BeamShaping #ARM #Coherent #ProcessStability #EVManufacturing #BatteryManufacturing