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    Investigation of the effects of machining parameters on the thrust force and cutting torque in the drilling of AISI D2 and AISI D3 cold work tool steels
    (Natl Inst Science Communication-Niscair, 2014) Kaplan, Yavuz; Okay, Senol; Motorcu, Ali Rıza; Nalbant, Muammer
    In this study, the effects of workpiece hardness, drill diameter, drill length and drilling parameters on thrust force and cutting torque are investigated in the drilling of AISI D2 and AISI D3 cold work tool steels under dry drilling conditions. The experiments are performed at three cutting speeds (5, 10 and 15 in/rnin) and three feed rates (0.04, 0.05 and 0.06 mm/rev). Workpiece hardness, drill diameter, drill length, cutting speed are considered as independent variables (machining parameters), and full factorial design is selected for experimental trials. Analysis of variance (ANOVA) is employed to determine the most significant, machining parameters on the thrust force and cutting torque. The predictive equations are developed in confidence intervals with the linear regression analysis to obtain the thrust force and cutting torque as a function of machining parameters and the correlation coefficients (R-2) of equations for thrust force and cutting torque are calculated as 92.7% and 84.1%, respectively. As a result of this study, it is found that all of the machining parameters are effective on the thrust force and cutting torque. Thrust force and cutting torque increase with the increase of workpiece material hardness, drill diameter, drill length, feed rate and number of holes, and decrease with the increase of cutting speed.
  • [ X ]
    Öğe
    The effects of process parameters on acceleration amplitude in the drilling of cold work tool steels
    (Springer London Ltd, 2015) Kaplan, Yavuz; Motorcu, Ali Rıza; Nalbant, Muammer; Okay, Senol
    This study investigated the effects of process parameters on acceleration amplitude in the drilling of AISI D2 and AISI D3 cold work tool steels using HSS twist drills of two different lengths. Workpiece hardness, drill length/tool overhang, cutting speed, feed rate, and number of holes drilled were chosen as the process parameters. In the tests made by using the full factorial (FF) design technique, the values of induced machining vibrations occurring on the workpiece during drilling were specified as the acceleration amplitude. Measurement results were evaluated by linear regression analysis, and a second-order equation was developed for the prediction of the acceleration amplitude. The correlation coefficient of the predictive equation at a 95% confidence level was calculated as R-2 = 0.703. The main and interaction effects of the process parameters on the acceleration amplitude were evaluated, and the percentage contributions of the process parameters to the acceleration amplitude were determined by variance analysis. In addition, scanning electron microscope (SEM) and optical microscope images of the drill wear were taken, and the wear characteristics and acceleration amplitude were correlated. The most effective parameters on acceleration amplitude were determined as the number of holes drilled, workpiece hardness, cutting speed, and feed rate. No significant effect of drill length/tool overhang was observed. With increasing cutting speed, number of holes drilled and the drill length/tool overhang, the acceleration amplitude values increased, although they decreased with increasing workpiece hardness.