AISI 8740 çeliğinin frezelenmesinde kesme gücü, özgül kesme enerjisi ve yüzey pürüzlülüğü karakteristiklerinin belirlenmesi

Abstract

 Determination of the cutting power, specific cutting energy and surface roughness characteristics of AISI 8740 steel  Calculation of the machining power using the electric current measured during the process and idle conditions  Up and down face milling characteristics of AISI 8740 steelFigure A. Proposed Model Architecture Purpose:The AISI 8740 steel is extensively in use for the high strength requirements in the industry. Yet, the literature survey revealed no published work on the machining characterization of the material. So, the machining characterization properties (namely, cutting power Pc, specific cutting energy ps and average surface roughness Ra) of AISI 8740 steel were found experimentally for different machining parameters (feed per tooth (uncut chip thickness)) fz and up and down milling conditions) in this study. Theory and Methods:In the experiments, the channels with 1 mm depth, 10 mm width and 50 mm length were machined using a 5-axis CNC milling machine with a 10 mm diameter two-inserted (cement carbide) face milling cutter. The table feed rate (Vf) values were selected as 2.67, 3.33, 4.17 mm/s. The rotational tool speeds (nt) were adjusted to keep the fz constant at 0.25, 0.20, 0.16 mm values, which will be used to calculate ps values in the experiments. The clamp-on amper meter was used in current measurements at idle and cutting conditions (Ii ve It, respectively). The Ra of the milled surfaces was measured using a tracing stylus type portable measurement device. The Pc ve ps values of the AISI 8740 steel were calculated using the measured current values in the experiments in up and down milling operations. The variation of Ra was investigated for varying fz values and up and down milling operations. Results:It The Pc values were between 217 W and 519 W for the experimental parameters used in up and down milling operations. The highest and the lowest Pc values were obtained at 4,17 mm/s setting (the highest Vf setting) in upmilling and 2,67 mm/s (the lowest Vf setting) in down-milling operation, respectively. A %2 to %15.5 lower Pc values were obtained in the down milling operation than the up-milling for the same Vf settings. The ps values of the material were found as 7.1-15.7 Ws/mm 3 for the parameter settings. The ps decreased with the increasing fz. The lower ps values were experienced in down milling than the up milling for all experimental conditions. The Ra values were decreased slightly with the increasing fz in up milling operations. The down-milling conditions yielded better Ra values (a 13-35% lower) than the up milling operations for the same machining parameters. Conclusion:The Pc values were decreased with increasing fz. A %2 to %15.5 lower Pc values were obtained in the down milling operation than the up milling for the same Vf settings. The ps values of the material were found as 7.1-15.7 Ws/mm 3 for the parameter settings. The lower ps values were experienced in down milling than the up milling for all experimental conditions. The Ra values were decreased slightly with...