29TH DAAAM INTERNATIONAL SYMPOSIUM ON INTELLIGENT MANUFACTURING AND AUTOMATION DOI: 10.2507/29th.daaam.proceedings.121 LASER CUT SURFACE ROUGHNESS MODELLING USING REGRESSION ANALYSIS Mirza Pasic, Derzija Begic-Hajdarevic, Izet Bijelonja This Publication has to be referred as: Pasic, M[irza]; Begic-Hajdarevic, D[erzija] & Bijelonja, I[zet] (2018). Laser Cut Surface Roughness Modelling Using Regression Analysis, Proceedings of the 29th DAAAM International Symposium, pp.0838-0845, B. Katalinic (Ed.), Published by DAAAM International, ISBN 978-3-902734-20-4, ISSN 1726-9679, Vienna, Austria DOI: 10.2507/29th.daaam.proceedings.121 Abstract In the modern industry the use of lasers has proven to be very useful due to the high precision and quality of cut. Important indicators of the cutting surface quality are roughness of the cutting surface   and   . In this research experiment is performed to analyse the influence of laser power , cutting speed  and assist gas pressure  as independent variables on dependent variables   and   during HSG fiber laser cutting of 1.4307 DIN stainless steel plates, 1 mm thick, using nitrogen as assist gas. During the experiment 75 samples are cut and 225 values of each cutting surface roughness   and   are measured. Data obtained during the experiment are analysed using regression analysis. Mathematical model is developed for each independent variable   and   depending on the significant independent variables. Surface roughness values   are compared and analysed according to the quality categories defined by ISO 9013: 2002 (E). It can be seen that regression analysis is good tool in modelling cutting surface quality   and   . Keywords: fiber laser cutting; surface roughness; regression; stainless steel plates; variables 1. Introduction The increasing need for production of high precision parts involves higher usage of unconventional cutting methods like laser cutting. During laser cutting there is no physical contact with sample, but thermal energy is used for cutting. Due to high temperatures caused by this laser cutting thermal process, material is melted and then removed by assist gas. Although laser cutting is very precise technique, influence of cutting parameters on surface roughness remains major research problem. For different materials it is important to provide optimal cutting parameters. Statistical control charts were used to analyse influence of cutting parameters on surface roughness [1]. Lower laser power and higher cutting speed lead to weakening of process control status of tungsten alloy using nitrogen as assist gas. The influence of cutting parameters on cut perpendicularity during HSG fiber laser cutting of stainless steel 1.4307 DIN, 1 mm thick, using linear regression analysis was analysed in [2], since cut perpendicularity is important aspect of cutting surface quality. Mathematical model was developed using linear regression analysis. The model shows that the cutting speed is the only significant independent variable in the model and that the values of cut perpendicularity increase with the increase of cutting speed values. - 0838 -