Abstract:

The hole quality varies particularly depending on the feed rate, cutting speed and tool geometry in the case of drilling of hard-to-machine materials with the drill. For this reason, the studies on the effects of feed rate and cutting speed on the drillability criteria such as cutting force, surface quality and dimension accuracy are still up to date although new drill quality and geometries are improved. In this study, the drillability of ferritic stainless steel with coated and uncoated carbide drill was investigated. The effects of feed rate and cutting speed on the thrust force, surface roughness and deviation of diameter were analyzed experimentally and statistically in drilling of the stainless steel. The experiments were carried out with three different cutting speeds (15, 30, 45 m/min) and the feed rates (0.12, 0.16, 0.2 mm/rev) with the carbide drill bit. Analysis of variance was applied to determine the effect levels of the drilling parameters on the machining outputs. According to the experimental results, it was determined that as the feed rate increases, the thrust force and surface roughness increases while the deviation of diameter decreases. Based on the experimental and statistical results, it was found that the coated carbide drill for average surface roughness and deviation of diameter displayed the average of 5.8% and 8.3% better performance than uncoated ones, respectively, while the uncoated drill demonstrated the average of 10% better performance than coated ones for thrust force.

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