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The extensive applicability of electrical discharge machining (EDM) in processing advanced materials is very tangible in itself. A realistic model of EDM process still remains an unachievable end, despite the numerous research efforts of sublime significance. This paper focuses on modelling and simulation of EDM process, to evaluate the influence of the input parameters, viz., current: 2–10 A and spark on time (Ton): 100–300 µs on the shapes of developed craters. It was observed that the crater radius-to-depth ratio (Rd) represent an incremental trend ranging from 1.679 to 2.575 with current and Ton, with the former having greater influence as such. The material removal rate (MRR) achieved a peak value of 121.533 mm3/min (at I = 10 A, V = 30 V and Ton = 300 µs). Finally, it can be presumed that the increase in Rd with current is the major contributor for higher surface roughness (Ra) for EDM machining at peak parametric values.

In this era of miniaturization, micro-EDM process plays a significant role. Micro-EDM due to its characteristic non-contact nature and ability to machine any material irrespective of its mechanical properties is ideal for the high precise micro-machining operations. The model describes the transient machining process using the two-dimensional heat conduction equation in cylindrical coordinates with flux boundary conditions. It also incorporates the different process elements like Gaussian distribution of heat flux and temperature-independent specific heat and thermal conductivity. A novel numerical scheme for the simulation of the crater shape formed on the workpiece during the micro-EDM process is introduced. This numerical scheme based on the finite volume method in cylindrical coordinates is developed for the real-time simulation of the process dynamics. The existing numerical schemes describe the material removal phenomenon without taking into effect the actual material removal mechanism. The proposed scheme is designed to replicate the anode erosion mechanism, where the phase change in the material, once the temperature exceeds the threshold value, is included. Single-spark micro-EDM experiments are conducted for the same simulation process parameter. The predicted crater shapes obtained from the real-time numerical scheme agree well with the experimental results with a relative error of less than 3%.

Discrete cosine transform is an algorithm used in image compression and plays significant role in signal and image processing. This paper provides an insight into VLSI-based pipeline architecture of DCT for low power utilization and low hardware circuit. The design will be optimized to provide maximum hardware utilization and minimum power consumption. The results obtained using the algorithm mentioned in this paper are compared with those obtained in [2]. The design is further extended for 24 bit RGB values wherein the pixel value corresponding to each RGB color is represented with its decimal equivalent. The modified 1D-DCT architecture for 8 bit input using Zynq board [10] has slice registers utilization of 0.29%, LUT utilization of 0.66%, operating frequency of 181.5 MHz and power consumption of 0.154 W. Hardware utilization and power consumption for 24 bit input are obtained as 0.66% and 0.159 W, respectively.

Micro-electric discharge milling (µEDM milling) is one of the important nontraditional micro-manufacturing processes which has the capabilities to make three-dimensional micro-components on difficult to machine materials like Ti–6Al–4V. In this study, the effect of various µEDM milling process variables on surface finish (Ra value) has been studied by adopting the Box–Behnken design of response surface methodology. Capacitance, voltage, electrode rotational speed and feed rate as well as their level of significance on surface roughness has been studied with analysis of variance. Results showed that capacitance is the important process variable which influences the responses.

Wire electrical discharge turning (WEDT) is a nontraditional machining process, which is used to generate accurate cylindrical components from difficult-to-cut materials. A model was developed to predict these parameters from the experimental data. In the present work, cylindrical workpieces of Inconel 825 are used as work material. The process parameters, viz., spark gap, rotational speed, pulse on time, and pulse off time were considered while conducting the experiments. The areal surface roughness was measured as the output response for quality improvement. Soft-computing-based artificial neural network (ANN) model was developed to predict the areal surface roughness value with the given data. The model prediction was compared with the experimental results for verifying the model and present good agreement with them. Genetic algorithm (GA) is used to estimate the optimal process parameters. The results of this study show that the computational approach, viz., GA, managed to estimate the optimal process parameters, leading to the minimum value of machining performance when compared to the result of experimental data.

Mechanical micromachining has gained wide acceptance in the manufacture of miniaturized components for a wide range of applications including aerospace, biomedical, electronics, etc. in recent decades. Microturning is one of the important machining techniques used for manufacturing these components. In micromachining, as the undeformed chip thickness becomes comparable with the cutting edge radius, size effect highly influences the material deformation mechanism. Therefore, the tool experiences a nonlinear variation in cutting forces and specific cutting energy, which accelerates the tool wear. The tool wear mechanism becomes even more complex in the case of micromachining of difficult to machine materials like Ti–6Al–4V alloy. Tool wear is influenced by the combined effect of mechanisms like material adhesion, abrasion, erosion, diffusive wear, fracture, etc. In the present work, the adhesive tool wear model, proposed by Usui et al. is used for the tool wear estimation in micro regime. The tool wear model is calibrated using a hybrid approach based on both finite element simulations and cutting experiments. Validation experiments are done to compare experimental and predicted flank wear rates. Results show that the predicted flank wear rates using Usui model, using calibrated constants, showed better agreement with experimental results.

The enhancement in process efficiency achievable by additive mixed electrical discharge machining during the processing of metal/alloy surfaces is a known facet. Nonetheless, its influence on the surface characteristics of the material remains scarcely evaluated. Hence, the evolution in tribological behavior of electrical discharge machined Ti6Al4V surfaces become the focal point of the present investigation. The process got assisted by silicon carbide powder (SiC, green, 1–10 μm) dispersed dielectric (de-ionized water) used as an insulator and the discharge medium. A computerized pin-on-disk tribometer (PoDT) was used to quantify the wear behavior of the developed surfaces. The experimentations varied based on distinction in the chosen speed (1.256 ms−1 (V1) and 1.884 ms−1 (V2)) and load (50 N and 100 N) conditions, respectively. The results depict that the tribological characteristics of the base material were enhanced by the surface doped heavily alloyed recast layer with secondary hard phases (SiC). At increased load (100 N), a catastrophic shift in wear mechanism caused by galling, led to the resultant delamination. The aftermath situation of implementing hard abrasives for surface modification is that at severe conditions (load/speed), the spalling of layers can have destructive effects on the mating surfaces.

Increasing demand on optical components in various fields such as consumer electronics and medical images requires fast and efficient machining of optical materials. This paper presents machining of brittle borosilicate glass in ductile mode to produce crack-free slots with good surface quality. Micro-end milling process was adopted in this study for machining. Three different cutters with diameter 0.3, 0.5, and 0.8 mm were selected to study the influence of the size of the cutter on the machining performance. Machining performance was assessed based on the surface roughness, slot profile, and chip formation. Finally, a brittle mode machining was performed with 1 mm diameter cutter and machining performance was compared with ductile mode machining. It was found that ductile mode machining produced a crack-free surface with surface roughness in the range of 250 nm and edge wall of the slots were free from cracks and damages.

Miniaturized products are getting great importance in highly growing industries such as aerospace, automobile, and biomedical due to the high demand and great applications of micro part/feature. Out of the different micromachining techniques, micro-end milling is one of the preferred processes because of its flexibility, ability to produce complex part, and high material removal rate. A detailed analysis of cutting force and areal surface roughness during micro-end milling of Inconel 718 is performed to analyze the effect of heat treatment on machining characteristics. The different heat treatments were performed on Inconel 718 at 920 °C. Micro-end milling experiments on different heat-treated samples by varying feed per tooth were conducted. The cutting force was measured using KISTLER dynamometer (9256C2) and areal surface roughness is measured using Alicona 3D optical profiler (Infinite Focus G5). Comparative analyzes of different heat-treated samples were analyzed. It was found that the cutting force, as well as areal surface roughness, shows a similar trend under different heat treatment conditions. At lower feed per tooth higher cutting force was observed with nonlinear pattern due to the higher plowing force. Size effect in cutting force was observed near to 1 µm feed per tooth. Outside the size effect region, both cutting force and areal surface roughness show the trend similar to macro-machining. The minimum value of areal surface roughness is obtained for water quenching condition. The minimum value of areal surface roughness obtained near to 3 µm, which is the cutting edge radius of the micro endmill cutter.

Wide range applications of micro-components make micromachining an important manufacturing method in industry. The distribution of machining-induced residual stresses has significant effects on the fatigue life, corrosion resistance, precision, and durability of parts. This study is focused on the modeling and validation of the residual stress induced in the workpiece after micro-end milling of Ti-6Al-4V. A coupled elasto-plastic model of mechanical stress inside the workpiece was developed to predict the residual stress. The contact between the cutter edge and the shear plane are considered a rolling contact which admits isotropic hardening only. In order to validate the developed residual stress model on the machined surface was evaluated by comparing the published literature result with similar cutting condition. It was found that the experimental and predicted values of both model and experimental results show hook-shaped distribution, with good agreement.

Micro-EDM drilling on difficult to machine materials has disadvantages like low MRR, high surface roughness, and others. In this manuscript the effect of two variants, workpiece vibration frequency and powder concentration in dielectric was applied together with the normal micro-EDM drilling operation. Voltage, Electrode Rotation Speed, Feed Rate, Workpiece Vibration Frequency, and Powder Concentration in Dielectric were taken as the five factors with Material Removal Rate (MRR) and Surface roughness along the sidewalls of the hole as the responses. Box Behnken design for five factors varied in three levels was taken as the experimental design. ANOVA was done on both the responses to find the significant factors and it was observed that all five factors were significant in both the cases. Multi-objective optimization using desirability approach was done and the optimum parameter setting was obtained. The optimized results were then validated with experiments and the relative error obtained was less than 4%.

Micro-end milling is one of the widely used micromachining techniques in industries and research organizations to produce microfeatures having complex 3D shapes with high flexibility and high material removal rate. The analysis of areal surface roughness, surface defect, and microhardness are important for understanding the surface characteristics of the machined surface. This paper focused on the analysis of areal surface roughness, surface defect, and microhardness during micro-end milling on Inconel 718. Inconel 718, a nickel-based superalloy, was used as the workpiece material due to the superior properties such as high hardness, high strength to weight ratio, resistance to high-temperature loading, and corrosion resistance. Areal surface roughness and microhardness were taken as responses to understand their variations with feed per tooth at a constant depth of cut and speed. The feed per tooth is selected by giving importance to both inside and outside the size effect zone. It was observed that the areal surface roughness shows a decreasing trend initially at lower feed per tooth and then it shows an increasing trend outside the size effect region. The minimum value of areal surface roughness (Sa) was found to be in the range of 3 µm, which is the cutting edge radius of the tool. Inside the size effect zone, severe strain hardening was observed. Size effect in microhardness was also found. Inside the size effect region, the microhardness increases with feed per tooth and outside size effect region microhardness shows a decreasing trend.

Disseminated arithmetic (DA) based construction of DCT for less circuit cost and less power consumption is presented here. Using disseminated arithmetic-less number of additions is used to the Discrete Cosine Transform by exploiting the time property of the DCT. The planned One-D DCT architecture is implemented on the Xilinx FPGA. The document describes the design of two-dimensional discrete cosine transform (DCT) which is widely used in image and video compression algorithms. The intention of this paper is to design a totally parallel distributed arithmetic (DA) architecture for two-dimensional DCT. DCT requires great amount of statistical computations including addition and multiplication. Multipliers are finally avoided in the projected design as an alternative DA-Based ROM and ROM accumulators are used, thereby rich-throughput DCT designs have been taken to fit the requirements of instantaneous applications. Disseminated arithmetic is a method of adaptation at bit stream for SOP or vector dot product to partition the multiplications. The speed is increased in the wished-for design with the fully corresponding approach. In this work, existing DA architecture for two-dimensional DCT and the proposed area efficient fully parallel DA architecture for two-dimensional DCT are realized. The modeling and synthesizing is performed using Xilinx ISE.