Reducing environmental risks in laser cutting: a study of low-pressure gas dynamics

High gas pressures (1.0-1.6 MPa) are employed in conventional inert laser cutting to achieve efficient material removal and high cut quality. However, this approach results in the emission of large quantities of by-products, which can pose a risk to human health and the environment. For applications such as nuclear decommissioning, where global extraction and containment can be challenging, hazardous by-product formation, rather than process efficiency, is the main priority. This paper demonstrates low-pressure (0.3 − 0.6 MPa) laser cutting techniques developed to reduce by-products. This study investigates the causal links between melt ejection and gas dynamic interactions in low-pressure laser cutting. Experiments were conducted using a 300 W Nd:Yb fibre laser to cut 304 stainless steel samples. Melt ejection and breakdown profiles were captured using a FASTCAM mini AX 200 camera. The lens combination fitted to the camera provided a spatial resolution of approximately 1 µm. The gas dynamic interactions were assessed through comparisons to existing studies of schlieren imaging in idealised environments. The results show that gas dynamics are crucial in melt ejection and breakdown mechanisms during laser cutting. The key findings of this study are images of breakdown mechanisms linked to low-pressure gas dynamics. The impact of this work is that breakdown mechanisms more favourable to reducing environmental risk have been demonstrated. A greater understanding of the risk is indispensable to developing new laser-cutting control methods for hazardous materials.