Life-Cycle Assessment of Laser Drilling in AISI 304 and Inconel 625: Energy, Gas Use, and Equipment Choice
S. Z. Shuja, B. S. Yilbas and M. M. Shaukat
Laser drilling can provide precise holes in hard‑to‑machine materials, yet its environmental assessment in terms of life cycle, is often confined to beam‑on energy. This consideration of narrow metric, in general, omits significant contributors to processes such as cooling and vacuum loads, warm‑up and idle power, assist‑gas production, and rework that substantially influence overall sustainability of the manufacturing process. The current study develops a gate-to-gate life-cycle assessment (LCA) for laser drilling of AISI 304 steel and Inconel 625 alloy. A 500 W Nd:YAG laser drilling process was assessed using a foreground inventory that includes laser electricity, vacuum-pump electricity with measured duty factor, shielding-gas (argon) consumption, and upstream impacts of removed material. The relevant parameters considered and tested in the analysis were drilled hole size, electricity mix (fossil fuel-based vs renewable), and laser substitution (Nd:YAG laser vs CO2 laser). Findings demonstrates that for AISI 304 steel, operational energy dominates global warming potential (GWP), whereas for Inconel 625 alloy the material term becomes comparable or dominant across toxicity, resource scarcity, and land-use categories. Argon production is a major contributor to ionizing radiation and water consumption, indicating that gas management is a high‑leverage opportunity for impact reduction. Increasing hole volume raises all impacts, the relative rise is larger for Inconel, notably for mineral resource scarcity and toxicity, reflecting Nickel, Molybdenum, and Tantalum intensive supply chains. At constant geometry, substituting a CO2 laser yields larger GWP reductions (36-38%) than a grid switch to renewable (13–14%), while the cleaner energy grid slightly increases ionizing-radiation and water use midpoints (CO2 substitution reduces water use by ~27%). The LCA therefore connects operational parameters (pulse and scan settings, gas flow, pump duty cycles, and equipment selection) and upstream procurement choices (electricity mix and assist‑gas selection) to per‑hole impacts, providing a documented foundation for co‑optimizing quality, productivity, and environmental performance in industrial drilling of AISI 304 steel and Inconel 625 alloy.
Keywords: Laser drilling, life cycle assessment, environmental impact, sustainable laser machining