No abstract

The aim of this study is to model and optimize the cutting conditions for the cutting force ( Fc) and average surface roughness ( Ra) that result from the machining of high-alloy white cast iron (Ni-Hard). The hard turning experiments were carried out on a CNC lathe with ceramic and CBN inserts. Cutting tool material, cutting speed, feed rate and depth of cut were chosen as the cutting conditions (control factors). Taguchi’s L18 orthogonal array was used for design of experiment. Optimum levels of the cutting conditions were determined using signal-to-noise ( S/N) ratio, which was calculated for machining output variables ( Fc and Ra) according to the ‘the-smaller-the-better’ approach. The effects of the cutting conditions on machining output variables were evaluated by the analysis of variance. The analysis of variance results showed that the depth of cut and feed rate were the most significant factors on Fc and Ra, respectively. Besides, the optimal cutting conditions for main cutting force and surface roughness were found at the different levels.

The purpose of this study is to utilize Taguchi method, which can prove to be a handy and effective tool for determining minimum vibration response of rotor-bearing system set to avoid running at critical speed. In the study, three test cases considering different coupling type (elastic, jaw, and solid) and disc location (disc location A, B, and C) were conducted to observe behavioral changes of the shaft system considering vibration signatures. Each test case was conducted for three different shaft running speeds of 12, 18, and 24 Hz. To find the minimum peak amplitude values by experimenting different combinations of the rotor-bearing system set needs a lot of experiments for reaching solution. Moreover, the solution proves costly because of the time consumed in doing many experiments. This fact depicts the importance of an efficient optimization method to be used. Taguchi method can determine the design parameters, which have the greatest influence on the solution through a very limited number of experiments, for finding optimum set of rotor-bearing system. The method is performed using an iterative procedure to gain an optimum design.