Investigation of the effects of drill geometry on drilling performance and hole quality

In this study, the effects of drill geometry on cutting performance and hole quality in the drilling process were investigated. Two newly developed drill geometries were compared with two commercially available drill geometries. In the drilling tests on GGG50 cast iron, 4 different drills, 4 different cutting speeds and 4 different feed rates were used for L16 experimental design. The drilling tests were performed with and without cutting fluid. The results were evaluated using the axiomatic design method, one of the multi-criteria decision making methods, in terms of thrust force, surface roughness, deviation on hole diameter and length of adhering workpiece material around the chisel edges. From the obtained results, it was seen that the best results were obtained from one of the newly developed drill geometries. In addition, wear test was carried out without cutting fluid using the drill which performed best. With this best performed drill, after 100 drilling operations in wet and dry conditions and after 1500 drilling operations in dry conditions, SEM images were taken from the used drills. After drilling 100 holes both in dry and wet drilling conditions, there was almost no wear on the drills. However, some adhered workpiece material was seen on the drills. In addition, the amount of adhered workpiece significantly increased in dry drilling condition.