DEVELOPMENT OF CURVED HOLE MACHINING METHOD Monica MOŢ 1 and Carmen PURCAR 2 1 TVET Cluster Highschool of Sighisoara, Sibiu, Romania 2 “Lucian Blaga” University of Sibiu, Romania Abstract: The paper presents the construction of a special device that permits the machining of curved holes by electrical discharge machining (EDM). An example is described of the production of a curved hole in a workpiece and from the experimental results it is found that the mechanism can perform a stable electrical discharge machining. Keywords: Curved hole, Electrical discharge machining, device 1. INTRODUCTION Machining curved holes by means of electrical discharge machining implies the development of a device installed on an EDM which converts the translational motion into a rotational motion. Researches were performed on transformational motion mechanisms to be used in designing of the device. The most suitable mechanisms are presented in the figure 1. Fig. 1 Transformational mechanisms. A technical analysis on the above mechanisms is performed considering the technical criteria to be fulfilled by the experimental device as it is shown in the figure 2. The cinematic parameters reproducibility is the most important criterion for a stable gap in electrical discharge machining. The second important criterion is the device precision. Less important criteria for the experimental device designing are the liability, the design complexity and the limit gauge. Table 1 shows the score of each mechanism according to the bibliography. Fig. 2 Technical criteria Table 1. Mechanism scores Mechanism Technical criterion Rack and pinion Slider- crank Gearing friction Belts and pulleys Cinematic parameters reproducibility (0,22) 2,20 2,20 2,20 2,20 Device precision (0,19) 1,90 1,90 1,52 1,90 Sensitivity (0,14) 1,12 1,40 1,12 1,40 Liability (0,17) 1,70 1,70 1,36 1,53 Handling (0,11) 1,10 1,10 1,10 1,10 Design complexity (0,06) 0,43 0,54 0,48 0,60 Total score 8,45 8,84 7,78 8,73 Transformational motion mechanisms Rack and pinion Slider-crank Gearing friction Belts and pulleys Device precision Design complexity Liability Limit gauge Technical criteria Cinematic parameters reproducibility Nonconventional Technologies Review – no. 4/2009 77