267 Canadian Journal on Technology Innovation, Vol.1 , 2014 Hole Taper in Laser Micro-drilling Operation on Advanced Engineering Materials: A Comparative Study T.Samanta 1 , R. Biswas 2 , A.S. Kuar 3 and S. Mitra 4 1,2 Mechanical Engineering Department, MCKV Institute of Engineering, 243 G.T. Road(N), Liluah, Howrah -711204, India 1 E-mail: samanta.tapishnu@gmail.com 2 E-mail: ranjib_biswas@rediffmail.com 3,4 Production Engineering Department, Jadavpur University, Kolkata –700 032, India 3 E-mail: arunanshu@rediffmail.com 4 E-mail: souren_mitra@sify.com Abstract—This paper presents the parameter interactions and comparison between three controllable process parameters namely, lamp current, pulse frequency and air pressure on hole taper in Nd:YAG micro-drilling operations. The investigation has been done in order to assess the effect of the selected parameters and also material properties in laser micro-drilling operations. Micro-drilling experiments have been conducted for Gamma-Titanium Aluminide, Alumina-Aluminium interpenetrating phase composites (IPC) and Titanium Nitride-Alumina ceramic composite. A response surface methodology called the central composite design (CCD) was employed to plan the experiments in order to achieve required information with reduced number of experiments. Index Terms— Nd:YAG Laser Micro-drilling, Process Parameters, Response Surface Methodology, Hole Taper, Gamma-Titanium Aluminide, Alumina-Aluminium, Titanium Nitride-Alumina 1. INTRODUCTION Laser material processing technology has been used to manufacture desired parts rapidly using subtractive and addictive methodology [1−2]. Recently, the application field of the laser drilling process has been extended due to the growth in the market of electronics, computers, communication products, and automotive parts [3−4]. The non-contact machining characteristics of the laser drilling process can reduce appreciably problems related to mechanical piercing and boring of thin sheets, such as serious deformation of the cut part, eccentricity of the hole and crumbling of the cut section, induced by direct contact of tools with the sheet metal [3]. The merits of Nd׃YAG laser, which includes a high energy density, distinguished focusing characteristics, a narrower heat affected zone, a better hole edge profile, and the capability of the enhanced transmission through plasma, make it an interesting application for precise sheet metal drilling [1]. Nd:YAG laser beam micro-drilling operation has been performed on Gamma-Titanium Aluminide, Alumina- Aluminium IPC and Titanium Nitride-Alumina composite. Gamma-Titanium Aluminide (Ti- 44.5, Al- 2, Cr- 2, Nb- 0.3B (at %)), an advanced material has already performed well in laboratory tests as well as in the field of turbine blades, engine valves, seal supports, cases, metal cutting tools, missile components, nuclear