ANALYSIS AND OPTIMIZATION OF SURFACE ROUGHNESS IN CO2 LASER CUTTING OF P265GH STEEL

This paper is focused on the analysis and optimization of surface roughness obtained in CO2 laser cutting of 4mm thick P265GH steel plate using oxygen as assist gas. For the purpose of experimental investigation central composite face-centered factorial design with 3 factors was realized. Assist gas pressure, cutting speed and nozzle diameter were considered as input controllable parameters and were systematically varied at 3 levels during the experimentation. Upon realization of experimental trials and measurements of surface roughness, second order non-linear mathematical model for the prediction of surface roughness was developed. Analysis of the developed model revealed the existence of significant parameter interaction effects. It has been observed that the effect of a given parameter on the surface roughness is varying and dependent on the settings of the other parameters. For each nozzle diameter a combination of assist gas pressure and cutting speed which yields minimal surface roughness was determined with the use of contour plots.