This paper reports an experimental investigation on continuous CO₂ laser cutting of polymethylmethacrylate (PMMA) sheet. The influence of four process factors (laser power, cutting speed, assisting gas pressure and sheet thickness) on five process responses (kerf deviation, top heat affected zone, bottom heat affected zone, maximum surface roughness and rough area) has been investigated. The experimental plan was established based on Taguchi L₁₈ mixed design. The kerf geometry and heat affected zones have been measured using polarising light microscopy technique, while the surface roughness was evaluated using 3D laser scanning confocal microscope. Regression models have been derived to correlate different process responses with different process factors. The cut surface could be classified into three zones: rough zone, moderate zone and soft zone. The rough area is increased by increasing gas pressure and laser power and by decreasing the sheet thickness and cutting speed. Increased kerf deviation has been observed at high cutting speed, laser power and gas pressure. High laser power and low cutting speed produced worst surface roughness and wide heat affected zone. Therefore, it is recommended to use low laser power and high cutting speed to minimize the heat affected zone and the surface roughness. However, increasing the cutting speed may result in high kerf deviation.

本文报道了连续CO ₂激光切割聚甲基丙烯酸甲酯（PMMA）板材的实验研究。研究了四个工艺因素（激光功率，切割速度，辅助气体压力和板厚）对五个工艺响应（切缝偏差，顶部热影响区，底部热影响区，最大表面粗糙度和粗糙区域）的影响。根据田口L ₁₈建立了实验计划混合设计。缝隙几何形状和受热影响区域已使用偏光显微镜技术进行了测量，而表面粗糙度则使用3D激光扫描共聚焦显微镜进行了评估。已经获得了回归模型，以将不同的过程响应与不同的过程因素相关联。切割面可分为三个区域：粗糙区域，中等区域和软区域。通过增加气压和激光功率以及通过减小片材厚度和切割速度来增加粗糙区域。在高切割速度，激光功率和气压下，观察到的切口偏移会增加。高激光功率和低切割速度会产生最差的表面粗糙度和较宽的热影响区。因此，建议使用低激光功率和高切割速度以最小化热影响区和表面粗糙度。但是，提高切割速度可能会导致较高的切缝偏差。