Advance Material Research, ISSN: 1022-6680, 2009. (Scopus and EI Indexing) Prediction Modelling of Surface Roughness for Laser Beam Cutting on Acrylic Sheets M.M.Noor 1,a , K.Kadirgama 1,b , M.M.Rahman 1,c , N.M.Zuki.N.M. 1,d , M.R.M.Rejab 1,e , K.F.Muhamad 1,f , Julie J Mohamed 2,g 1 Faculty of Mechanical Engineering, Universiti Malaysia Pahang, Tun Razak Highway, 26300 Gambang, Kuantan, Pahang, Malaysia. Email: a muhamad@ump.edu.my , b kumaran@ump.edu.my , c mustafizur@ump.edu.my , d nikzuki@ump.edu.my , e ruzaimi@ump.edu.my , f fikri@ump.edu.my , 2 School of Material Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang, Malaysia Email: g srjuliewatty@eng.usm.my Keywords: Laser beam cutting, Box-Behnken design, surface roughness, acrylic sheets Abstract. This paper develops the predicting model on surface roughness of laser beam cutting (LBC) for acrylic sheets. Box-Behnken design based on Response surface method was used to predict the effect of laser cutting parameters including the power requirement, cutting speed and tip distance on surface roughness during the machining. Response surface method (RSM) was used to minimize the number of experiments. It can be seen that from the experimental results, the effects of the laser cutting parameters with the surface roughness were investigated. It was found that the surface roughness is significantly affected by the tip distance followed by the power requirement and cutting speed. Some defects were found in microstructure such as burning, melting and wavy surface. This simulation gain more understanding of the surface roughness distribution in laser cutting. The developed model is suitable to be used in the range of (power 90 to 95, cutting speed 700 to 1100 and tip distance 3 to 9) to predict surface roughness. 1. Introduction Laser light differs from ordinary light due to it has the photons of same frequency, wavelength and phase. Thus, unlike ordinary light laser beams are high directional, have high power density and better focusing characteristics [1,2]. These unique characteristics of laser beam are useful in processing of materials. The laser beams are widely used for machining and other manufacturing processes such as cutting, drilling, micromachining, marking, welding, sintering and heat treatment. Lear beam machining (LBM) is a thermal energy based advanced machining process in which the material is removed by melting, vaporization and chemical degradation. When a high energy density laser beam is focused on work surface the thermal energy is absorbed which heats and transforms the work volume into a molten, vaporized and chemically changed state that can be easily be removed by flow of high pressure assist gas. LBM can be applied to a wide range of materials such as metals and non-metals. Laser surface texturing may be an ideal technology for applications in mechanical face seal, as well as in various components in engine such as piston ring and cylinder and thrust bearings, involving creation of an array of micro dimples or channels artificially distributed on the mating surface with a pulsed laser beam [3 -4]. The most widely used lasers for sheet cutting are continuous wave (CW), CO 2 and pulsed Nd:YAG [5]. Pulsed Nd:YAG laser cutting becomes an excellent cutting process because of high laser beam intensity, low mean beam power, good focusing characteristics, and narrow heat affected zone (HAZ) [6, 7]. Lei et al. [8] have found that the laser-assisted turning (LAT) of silicon nitride ceramics economically reduces the surface roughness and tool wear in comparison to only conventional turning process.