Effects of CO₂ laser parameters on quality of laser cut beech wood (Fagus sylvatica L) surface and extent of heat affect zone

Laser cutting of wood offers precision and speed advantages over traditional methods. This study investigates the effect of CO₂ laser processing parameters such as position of focal point, cutting speed, and gas pressure on cut surface quality of beech wood (Fagus sylvatica L.), measured in terms of color change and surface roughness. Additionally, the extent of the heat-affected zone was assessed using FTIR spectroscopy and PCA analysis of FTIR spectra. All color coordinates (L*, a*, and b*) decreased after laser cutting, with the most significant reduction in the lightness index (L*), indicating a darkening of the surface. The total colour change (∆E*) was primarily affected by the change in lightness index (∆L*) and the contribution of ∆a* and ∆b* to ΔE * was very less. The color change was observed to be the lowest when the focal point was positioned one-third from the top surface. Surface roughness increased as the position of focal point moved from the surface towards the center of the sample, suggesting a deterioration in surface quality. Conversely, cutting speed and exhaust gas pressure did not affect surface quality. FTIR spectroscopy revealed changes in specific functional groups due to heat generation during laser cutting. However, chemical degradation was localized to the cut surface and did not affect regions even 200 μm below the cut surface.