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A Critical Review on the Machining of Engineering Materials by Die-Sinking EDM
Published in Chander Prakash, Sunpreet Singh, J. Paulo Davim, Advanced Manufacturing and Processing Technology, 2020
P. Sreeraj, S. Thirumalai Kumaran, M. Uthayakumar, S. Suresh Kumar
Rotary tool has been considered in machining of high-chromium high-carbon die steel using argon gas–assisted EDM (AGAEDM) by Singh et al. [28]. In EDM process, workpiece along with tool experiences an exorbitant heating in the vicinity of plasma channel. In order to overcome this issue, an adequate attention should be given in the selection of tool material, electrode polarity, and process parameters. According to Toren et al. [29], erosion of materials is caused by local melting and heating of workpiece and tool electrode. Electrode wear is common process, when high MRR with good SQ is required. Khanara et al. [30] have produced ZrB2–40 wt.% Cu composite tool for machining mild steel, and it has shown a decrease in TWR over pure Cu tool. While comparing with conventional copper tool and ZrB2–Cu composite tool, average SR and diameter overcut produced on the workpiece are found to be more in the case of composite tool. This work has suggested some results that are promising for the manufacturing industry. Islam et al. [31] have devised a method of removing burrs from drilled holes of carbon fiber–reinforced polymer composites by EDM. They have used four different types of electrodes copper, steel, brass, and aluminum for EDM to remove burrs from the previously drilled holes. Best deburring has been performed by copper electrodes.
Optical Cochlear Implants
Published in Francesco S. Pavone, Shy Shoham, Handbook of Neurophotonics, 2020
C. P. Richter, Y. Xu, X. Tan, N. Xia, N. Suematsu
High-efficiency microscale Light Emitting Diodes (µLEDs) are an option for optogenetic approaches. Light sources were blue μLEDs (Pico LED, Rohm Semiconductor, Kyoto, Japan). The dimensions of the µLEDs (1,000 × 600 × 200 μm) are large when considering the size of the resulting multi-channel optrode, which has to be inserted into a cat or human cochlea. Therefore, the dimensions of the light source were minimized by trimming the carrier to 500 × 500 × 200 μm by either cutting them with a sharp blade or by grinding them down with a DREMEL rotary-tool. The chip has an InGaN structure with 33 mW of power dissipation. The peak forward current in constant wave mode is 10 mA, and is 50 mA in the pulsed mode. In pulsed mode the duty cycle is 1:10. The operating temperature is −100 to 85°C. The scanning angle is about 140 degrees. The radiation wavelength is 465–475 nm. The luminous intensity is about 25 mcd (millicandelas = millilumens/steradian). The radiant intensity or radiant flux Ie of the source can be estimated Ie=IvK(470nm)=25200mlmsrWlm=0.125mW/sr
Hybrid Machining of Metal Matrix Composites
Published in Subhash Singh, Dinesh Kumar, Fabrication and Machining of Advanced Materials and Composites, 2023
Sahil Sharma, Farhan Ahmad Shamim, Akshay Dvivedi, Pradeep Kumar, Tarlochan Singh
It is important to note that in RM-ECDD, a rotary tool electrode helps in electrolyte replenishment and evacuation of debris from the machining zone. It also helps to make the gas film thinner formed around the tool electrode [40]. The thin gas film modifies the characteristics of discharges and hence improves the machining performance. The obtained results from this study showed that the RM-ECDD process fabricated a 23% higher aspect ratio hole than conventional ECDD.
Developments in tandem micro-machining processes to mitigate the machining issues at micron level: a systematic review, challenges and future opportunities
Published in Machining Science and Technology, 2022
Sahil Sharma, Tarlochan Singh, Akshay Dvivedi
EDM drilling plus ECM tandem micro-machining process have been utilizing to fabricate the micro through-holes by adopting two different strategies. In both strategies, the same machining set-up, power unit and tool electrode were employed for drilling and finishing operations. However, different working fluids were used in both cases. In the first machining strategy, Chung et al. (2009) fabricated the micro through holes in 300 µm thick stainless steel (AISI 304). Firstly, holes were drilled with a 90 µm tungsten carbide (WC) tool electrode and high resistive (i.e., 2 MΩ cm) deionized water by EDM process. The EDMed holes were subsequently finished by ECM by varying the voltage from 60-100 V. The schematic view of the machining configuration used for both operations is shown in Figure 8. For the finishing operation, the capacitor was removed from the machining setup to suppress the spark discharges, as illustrated in Figure 8b and c. The increased applied voltage from 60 V to 100 V increased the hole radius from 5 µm to 9 µm. The accuracy and finishing of fabricated holes were further improved by providing tool rotation during the ECM process. Without tool rotation, uneven dissolution occurred owing to unflushed metal hydroxides, resulting in non-uniform hole profiles. The rotary tool helped to evacuate the metal hydroxide from the machining zone and thus promoted uniform dissolution. The application of the ECM process with 2 MΩ cm deionized water at the applied voltage of 80 V and tool rotation of 1200 rpm for 6 min reduced the surface roughness from 0.225 µm to 0.066 µm (Figure 8d and e). However, the excessive dissolution from the entrance and exit of the hole during ECM caused the reverse barrel shape holes.
Effect of tool rotation in near-dry EDM process on machining characteristics of HSS
Published in Materials and Manufacturing Processes, 2019
Vineet Kumar Yadav, Pradeep Kumar, Akshay Dvivedi
The present investigation was aimed to explore the capabilities of rotary tool near-dry electrical discharge machining process. Experiments were conducted on HSS (AISI M2) using five process parameters (tool rotation speed, current, pulse on time, liquid flow rate (LFR), and gas pressure). The experimental results of MRR, SR, and hole overcut (HOC) were investigated. In addition, theoretical and technical foundation for the industrial application of the RT-ND-EDM were recognized and discussed.
Review on tools and tool wear in EDM
Published in Machining Science and Technology, 2021
Deepak Sharma, Somashekhar S. Hiremath
Ghoreishi and Atkinson (2002) compared the machining characteristics by using rotary, vibratory, and vibro-rotary tool in electric discharge machining. Results suggest that low-frequency range does not show a considerable increase in MRR but at a high ultrasonic frequency, a combination of rotary and vibration increases surface roughness, MRR, and TWR. So to obtain optimal parameters, compromise should be made among MRR, TWR, and surface roughness.