Influence on machinability and form tolerance of Inconel 718 in Edm using different diameter multi hole Cu electrodes

Abstract

This research aims to examine the machinability and form tolerances in die sinking EDM for Ni-based superalloy with different diameter internally engraved hole of the multi-hole copper electrode. Manufacturing of superalloys with close tolerances is becoming a major area for primary research in defence and aerospace industries due to their particular characteristics. Therefore, this work focuses on an experimental analysis to improve the productivity and Material Removal Rate of Inconel-718 with close tolerances. The most dominating process constraints, viz. hole diameter of Multi-hole electrode (D), Peak current (I p ), Pulse on Time (T on ) and dielectric fluid pressure were selected as process constraints to conduct experimental trials. The Material Removal Rate, EWR and form tolerances were considered as output responses. The experimental outcomes were optimized by Taguchi analysis and multi-parametric optimization method GRA. A Fuzzy logic model using Matlab was developed for the prediction of performance parameters, namely MRR, EWR, circularity and cylindricity with respect to changes in input parameters. Three MF's ('Trimf-triangular membership functions') were allocated to each input response, whereas five MF's were allocated to output responses. The Fuzzy model shows the 94.01% accuracy between the experimental values and the predicted values. From the results, it is concluded that the use of a multi-hole electrode leads to a higher rate of MRR. Moreover, the form tolerance deviation improves with the increment of T on value. The optimized parameters showed a considerable improvement in the process and will facilitate the aerospace and defence industries to improve the productivity of Inconel-718 with close tolerance.

On Geometrical Characteristics of WC-Co Round Cavities After ED-Machining with Different Grades of CuW Electrodes

“…Data pertaining to circularity, cylindricity and perpendicularity of round cavities are scarce in EDM literature 11 . Circularity is defined as a condition of a surface of revolution (sphere, cone, and cylinder) where all points of the surface intersected by any plane perpendicular to a common axis (cone, cylinder) or passing through a common center (sphere) are equidistant from the axis of the center 12 .…”

Electric discharge drilling with gas-assisted multi-hole slotted tool

“…It can be inferred that high surface roughness was generated by the combination of high duty cycle and low pulse duration. At high duty cycle, large discharge energy and impetuous force were produced which resulted in larger sized carters on the workpiece, as a consequence, the surface finish decreased with a rise in duty cycle [21,29]. At the same time, for high pulse duration, the enlargement of the plasma channel took place in the gap of electrodes, because of which the peak current and magnitude of impulsive force decreased [22].…”

“…This leads to high temperatures in the machining area, which increased the wear of the electrode alongside MRR, thereby increasing the wear ratio of the electrode [10]. Moreover, at high discharge current, a lot of disintegrated particles get amassed in the machining gap that in the end enhanced the electrode wear [21]. From the Figure 8(a), one can see that in AAEDD, EWR was lower than in the REDD.…”

“…It can be seen that EWR had an inverse correlation with a pulse on time. This can be represented the reason that the span of the plasma channel extended at high value of pulse on time, which at last cut down the high temperature of the tool surface [21]. In addition, the black carbon produced by cracking the hydrocarbon oil that is stuck on the electrode surface at a longer pulse duration.…”

“…The findings show that the proposed tool has self-flushing characteristics and is more potent in the evacuation of eroded materials from the machining zone than the conventional solid tool. Kumar and Dhanbalan [21] investigated the machinability and tolerances of inconel-718 employing a multi-hole electrode with an engraved hole resulting in increased MRR and a lower tolerance discrepancy.…”