522 Vol. 38, No. 4 (2016) 522-529 Tribology in Industry www.tribology.fink.rs Modeling of Surface Roughness in Plasma Jet Cutting Process of Thick Structural Steel I. Peko a , B. Nedić b , A. Đorđević b , D. Džunić b , M. Janković b , I. Veža a a Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Split, Ruđera Boškovića 32, 21000 Split, Croatia, b Faculty of Engineering, University of Kragujevac, Sestre Janjić 6, 34000 Kragujevac, Serbia. Keywords: Plasma jet cutting Surface roughness Modeling Experiment Structural steel A B S T R A C T Today highly competitive market and demands for obtain high surface finish and machining of complex shape geometries replace conventional machining processes with non-conventional. Plasma jet cutting is one of these non-conventional processes that primary uses a thermal energy of highly ionized gas to cut specified material and blow molten metal away. Main advantages of plasma jet cutting process are high speed of cutting, cutting different types of materials, the quality of cut and moderate to low investment costs. This paper presents experimental results concerning the surface roughness variation at plasma jet cutting of structural steel S235JRG2 plate thickness of 15 mm. Using the experimental data artificial neural network (ANN) model was developed in order to predict the surface roughness in terms of two input parameters, cutting current and cutting speed. After the prediction accuracy of the developed model was validated, the model was used for analyzing influence of input parameters on process response values. © 2016 Published by Faculty of Engineering Corresponding author: I. Peko Faculty of Electrical Engineering, Mechanical Enginering and Naval Architecture, University of Split, Ruđera Boškovića 32, 21000 Split, Croatia E-mail: ipeko@fesb.hr 1. INTRODUCTION Today, different non-conventional thermal processes can be found in many applications in metal processing and shipbuilding industry. These processes include oxy fuel cutting, laser cutting and plasma jet cutting. They can be used for the cutting various types of materials at various thicknesses. Plasma jet cutting process has many advantages which can help the modern company to survive in a turbulent market. Main benefits that characterize this process and position it in front of the laser and abrasive water jet cutting are optimal combination of cut quality, productivity and costs for mild steel, stainless and aluminium cutting. Competitive investments, high productivity, long consumables life and lower costs per part lead this technology to become a practical alternative to other processes such as laser and abrasive water jet cutting. Plasma jet cutting process was developed at the end of 1950s. Plasma can be defined as the fourth state of substance which is obtained by supplying a tremendous amount of energy to gas RESEARCH