Modelling and multiresponse optimization for minimizing burr height, thrust force and surface roughness in drilling of ferritic stainless steel

Abstract

Although there have been many studies on the drillability of various grades of stainless steel, there is no scientific research on the drilling of ferritic stainless steel. Also, the burr at hole exit means the need for secondary machining operation and indirectly increases the production cost. Thus, this study focused on the modeling and minimizing burr height (Bh), thrust force (Fz) and surface roughness (Ra) during drilling of AISI 430 ferritic stainless steel with uncoated carbide drill under dry condition. Bh, Fz and Ra based on different cutting speed and feed rates were measured during drilling tests, and then cutting parameters were optimized by applying Taguchi based grey relational analysis. Moreover, the mathematical models were created by employing the response surface method to predict the machining outputs. The thrust force and the surface roughness decreased while the burr height increased with the increase in cutting speed. Uniform burr formation with drill cap was observed for all machining parameters under dry environment. The effect levels of feed rate and cutting speed on burr height were determined as 54.82% and 44.67%, respectively. These result shows that cutting speed is as important as the feed rate during the drilling of the ferritic stainless steel. In the current study, the best suitable levels of feed rate and cutting speed were detected as 0.12 mm/rev and 45 m/min for minimizing Bh, Fz and Ra. The coefficients of determination obtained by RSM indicated a relationship in high level between the cutting parameters and machining outputs.