Dry EDM is an emerging EDM technology, which uses gas as dielectric fluid. Due to low density of gaseous dielectric, the process experiences i) unconstrained plasma expansion thereby reducing the effective material removal rate (MRR) and ii) inefficient disposal of debris. This work proposes use of electrodes with peripheral slots to provide more space for the flow of dielectric for effective debris disposal and consequently improve MRR. In this regard, a comprehensive experimentation using Taguchi L 16 orthogonal array has been planned initially to optimize the number of peripheral slots on the electrodes, and then to understand the effect of the slots on material removal, tool wear, oversize and depth achieved as a function of processing conditions. It is observed that the optimum number of peripheral slots on electrode for effective debris evacuation is four for the electrode configuration used in this work. The statistical analysis shows that in dry EDM, discharge current (I), gap voltage (V), rotational speed (N) and pulse off-time (T off ) control MRR. Also, use of slotted electrodes significantly reduces the electrode wear rate, and attachment of debris particles on the electrodes.

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To achieve better precision of features generated using the micro-electrical discharge machining (micro-EDM), there is a necessity to minimize the wear of the tool electrode, because a change in the dimensions of the electrode is reflected directly or indirectly on the feature. This paper presents a novel modeling and analysis approach of the tool wear in micro-EDM using a systematic statistical method exemplifying the influences of capacitance, feed rate and voltage on the tool wear ratio. The association between tool wear ratio and the input factors is comprehended by using main effect plots, interaction effects and regression analysis. A maximum variation of four-fold in the tool wear ratio have been observed which indicated that the tool wear ratio varies significantly over the trials. As the capacitance increases from 1 to 10 nF, the increase in tool wear ratio is by 33%. An increase in voltage as well as capacitance would lead to an increase in the number of charged particles, the number of collisions among them, which further enhances the transfer of the proportion of heat energy to the tool surface. Furthermore, to model the tool wear phenomenon, a regression relationship between tool wear ratio and the process inputs has been developed.

The technological development of the 3D printing industry has been tremendous starting from stereolithography in the 1980 s. Low throughput and surface quality had been the major obstacles to this technology, which offers very limited constraints to the geometrical shapes. In this work, we designed a lowcost volumetric 3D printer that, unlike traditional 3D printers, polymerizes the whole geometry within the revolving resin container. Optimized projections needed for the polymerization of target objects were developed in MATLAB R2020b using the concepts of tomographic reconstruction. The rotation of the resin container and the projections rate were matched to develop the target geometries after the oxygen depletion. Commercially available low viscous Anycubic plant-based resins were used as the printing material. 3D objects of centimeter scale could be manufactured in 30 seconds with extremely low surface roughness in the sub-micron range. The dimensional deviation of final components from the CAD model was found to be within 5%. The overprinting on existing solid structures was successfully experimented with and thus opens the way for future developments. Commercialization of volumetric 3D printers would result in mass production of complex customer-specific functional components which in turn boosts the manufacturing sector significantly.

The application of ultrasonic vibrations to a workpiece or tool is a novel hybrid approach in microelectrical discharge machining. The advantages of this method include effective flushing out of debris, higher machining efficiency and lesser short-circuits during machining. This paper presents a systematic analysis of the influence of kinetic effects of the ultrasonic vibrations on the material removal rate (MRR) and tool electrode wear rate (TWR). The tool wear ratio was estimated for the process at all processing conditions. The maximum variation in tool wear ratio is observed to be 82%. Therefore, MRR and TWR were independently analyzed by using three scientific tools: i) AOM plots, ii) interaction plots and iii) three-dimensional scatter plots. The increase in MRR is 47% corresponding to an increase in the maximum power of vibrations by 30%. The ultrasonic vibrations are found to be very effective at higher machining depths for achieving stable machining conditions. Regression equations were developed for MRR and TWR with capacitance, ultrasonic vibration factor, feed rate and machining time.