International Journal of Research in Advent Technology, Vol.7, No.5, May 2019 E-ISSN: 2321-9637 Available online at www.ijrat.org 455 Scotch Yoke Mechanism for Metal Specimen Polishing & Microstructure Analysis Saish N. Rivankar 1 , Prasanna C. Kattimani 2 , Gaurish Walke 3 , Dr. Akshay Nigalye 4 Department of Mechanical Engineering 1,2,3 , Agnel Institute of Technology & Design, Goa, 403-507, India 1,2,3 Department of Mechanical Engineering , 4 , Goa College of Engineering, Farmagudi, Goa, 403-401, India 4 Email: saish.rivankar@gmail.com 1 , pk.aitdgoa@gmail.com 2 , gaurishwalke88@gmail.com 3 , avn@gec.ac.in 4 Abstract-Preparation of metallographic specimen for revealing microstructure of metals or metal alloys is carried out in material science laboratories all over the world. To study microstructure of metal samples, various steps like sectioning, grinding, polishing, etching are performed, and this procedure requires skills and practice to produce specimen whose microstructure can be seen clearly under the optical microscope. In this research a new concept for polishing machine is proposed, which aims to eliminate all the factors that cause poor surface finish during manual polishing. The proposed polishing machine uses modified scotch-yoke mechanism. Machine minimizes skill and efforts required to prepare metallographic specimen. Index Terms-Metallographic Specimen; Polishing; Scotch Yoke Mechanism; Abrasive Surface. 1. INTRODUCTION Microstructure of materials affects mechanical properties and hence application of the materials is related to microstructure. Therefore, microstructure study is important tool in quality inspection of newly developed material, which includes metal and their alloys. Ma-chines such as SEM & TEM are available which have capability to study microstructure of materials both quantitatively and qualitatively. But these machines are very costly and needs good utilization factor for better productivity. These machines are not much suitable for educational institutes. Hence, to study microstructure analysis, institutes make use of optical microscope, which is low cost alternative for SEM and TEM. Under optical microscope qualitative analysis and comparative analysis of microstructure can be performed. To view microstructure of any material under optical microscope requires preparation of the metallographic specimen. Microstructure analysis involves specimen identification, sectioning, mounting, grinding, polishing, etching, microscopic analysis and hardness testing [1-2]. Machines for performing grinding and polishing are available with different methods of operation. They involve human interference which creeps in defect on polished surface, making it unfit for viewing microstructure under optical microscope. This requires re-polishing of specimen which leads to increase in cycle time and cost of machining [3]. This research focuses on developing a machine which polishes specimen for microstructure analysis. Preparing a specimen requires rough polishing and fine polishing. Rough polishing makes use of Silicon Carbide (SiC) Waterproof Emery Paper of lower grit size. Fine polishing requires rubbing rough polished specimen on velvet cloth with alumina powder to give mirror finish. Both operations are performed on developed machine which works on scotch-yoke mechanism, with minimum human interference. 2. LITERATURE REVIEW During the period 1513 to 1517, Leonardo da Vinci visualized a machine which could be used for grinding and polishing of telescope mirrors. In the concept shown in Fig. 1, circumferential area of polishing wheel is rubbed against the mirror to be ground. Mirror is placed on wheel which is rotated using gear train simultaneously during polishing [4]. Fig. 1. 1st Polishing machine by Leonardo da Vinci Another machine as shown in Fig. 2, visualized by Leonardo da Vinci, consists of crank-crank mechanism. Main disc carrying mirror rotates, whereas the polishing disc carrying the abrasive layer also rotates over the mirror causing abrading action. Rotation of link connected to cranks causes rotation of main disc about its axis. The other crank is connected to polishing disc through eccentric arm, thus causing revolving motion [4].