Numerical Simulation and Experimental Investigation in Gas-Assisted Laser Cutting of Cherry Wood

Gas-assisted laser cutting is an effective approach for improving the processing quality of wood; however, the internal gas flow characteristics within the narrow kerf and their relationship with kerf formation remain insufficiently understood. In this study, a gas flow field model was established using COMSOL Multiphysics 5.6, and cutting experiments were conducted using an 80 W CO2 laser system to investigate the effects of auxiliary gas type, inlet pressure, and nozzle-to-workpiece distance. The simulation results showed that helium-assisted cutting exhibited higher velocity retention, stronger pressure variation, and a more continuous wall shear stress distribution than air-assisted cutting under the investigated conditions. Increasing helium inlet pressure from 0.10 to 0.30 MPa increased the maximum jet velocity from 448.6 to 684.9 m/s, whereas increasing nozzle-to-workpiece distance mainly affected the free-jet region. Experimentally, helium assistance significantly reduced kerf width and surface roughness compared with air assistance at 0.10 MPa. Under helium assistance, kerf width decreased from 0.352 to 0.314 mm as pressure increased from 0.10 to 0.30 MPa, while surface roughness reached a minimum of 2.426 μm at 0.20 MPa. Inlet pressure significantly affected kerf width (p = 0.042) and surface roughness (p = 0.003), whereas no statistically significant effect on cutting depth was detected (p = 0.148). These findings provide insight into auxiliary gas flow behavior and its relationship with kerf formation during wood laser cutting, offering a reference for optimizing gas-assisted laser cutting processes.