Bonfring International Journal of Industrial Engineering and Management Science, Vol. 4, No. 3, August 2014 125 Microwave Drilling with Litz Wire using a Domestic Applicator Nitin K. Lautre, Apurbba K. Sharma, Pradeep Kumar and Shantanu Das Abstract --- The work presented in the paper shows a way to drill a blind hole on perspex material at 2.45 GHz frequency of microwaves using a domestic applicator of 700 W maximum powers. The approach was based on the approach was based on the application of a Litz wire coax as a monopole, to act like a drill bit with a heat source. The methodology involves no rotary but, single linear movement of tool inside a microwave applicator for drilling. A computer simulation on COMSOL for about 50 minute each run, was also used to show the heat distribution inside microwave applicator. The result of computer simulation helped to locate the optimized position of Litz wire inside the applicator for optimum heat generation. The experimental results show the feasibility of microwave drilling and limitations on perspex specimen in the used applicator. The work presented involves a new approach in the area of microwave drilling of materials on a customized domestic microwave setup. Keywords--- Applicator, COMSOL, Drilling, Litz, Microwave, Perspex I. INTRODUCTION ICROWAVE energy and drilling process are two different popular areas in the field of engineering. Microwave concepts are relatively newer to that of drilling. Many of the researchers have tried to overcome the limitation of traditional drilling process with the newer emerging concepts. Microwave drilling is one such approach presented in the year 2000 [1]. The importances of some of applications in the area of microwave material processing are rising in terms of their popularity and consequently researched [2]. The active research areas include microwave assisted sintering, material interaction, modeling, equipment and its design, measurements, etc. Most of the research works in microwave assisted material processing however are limited to processing of ceramics followed by composites. Nitin K. Lautre, Research Scholar, Department of Mechanical and Industrial Engineering, Indian Institute of Technology, Roorkee, India. E- mail:nfl_123@rediffmail.com Dr. Apurbba K. Sharma, Associate Professor, Department of Mechanical and Industrial Engineering, Indian Institute of Technology, Roorkee, India. E- mail:akshafme@gmail.com Dr. Pradeep Kumar, Professor, Department of Mechanical and Industrial Engineering, Indian Institute of Technology, Roorkee, India. E- mail:kumarfme@gmail.com Shantanu Das, Scientist - H, Reactor and Control Division, Bhabha Atomic Research Center, Mumbai, India. E- mail:shantanu@magnum.barc.gov.in DOI: 10.9756/BIJIEMS.6053 Majority of the work reported was confined to metallurgical processing of material. However, microwave assisted mechanical processes received very less attention. Some of the developments in the areas of application of microwaves for various processes like sintering, cladding, melting, coating, glazing, joining, cladding and co-axial cable assisted drilling, etc. are reported [3] – [8]. The area of microwave drilling on various materials like concrete, glass, ceramics, basalts, silicon, and bones are well envisaged and explored [9] – [12]. The application of bone drilling in biomedical engineering, electronics industry and aeronautical engineering involves the majority of recent drilling applications for small size holes [13] – [18]. Researchers have tried to drill hole in perspex of 2.5 mm thick through a 1064 nm diode laser. The power of 1 W without decrease in pressure and 2.45 W at a low pressure of 60 mm Hg of air was used to drill a hole [19]. A careful control of various parameters like the preparation of precise nozzle diameter, its focal point, lens effect, speed of cut, cutting power, standoff distance, hole circularity, spatter thickness, material removal rate and assists gas pressure adjustment add complexity. These controls hinder the drilling process for attaining a high aspect ratio holes with low taper ratio [20] – [22]. An attempt is made to use different wavelength the degrade perspex to cause burning, cracking, boiling in and around the imposed laser part and nearby. The wavelength varied from near infrared (1064 nm) to visible (532 nm) to ultraviolet ( 266 nm) wavelength. At 266 nm the photo chemical dissociation by covalent bond breaking (photo-ablation) was more dominating than thermal ablation in perspex [23] – [24]. A high aspect ratio of 300- 600 for hole ranging from 10 – 100 micron is reported [25] – [26]. For blind holes a surface modification is prepared by exposing perspex to laser beam. The thermochemical damages due to carbonization of perspex into small spots are reported [27] – [28]. Conventionally the drilling of perspex establishes the significant parameter to be controlled for effective drilled hole as the speed, feed rate, thrust force, tool wear, delamination [29] – [30] and hole shrinkage. A high speed steel drill bit is related significantly with power and acoustic emission. The acoustic emission is unavoidable and is due to assembly of mechanically vibrating and rotating system [31]]. Microwave drilling makes an attempt to minimize the problem observed in conventional and non conventional (laser) drilling process. It has been found that very few researchers are active in the domain of microwave drilling at present. The behavior of microwave drilling in a closed applicator is infact, highly complex as it is governed by various phenomena. Concepts like dielectric behavior of material in high temperature, hot spot formation, thermal runaway as well as safety M ISSN 2277-5056 | © 2014 Bonfring