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This paper discusses the comparison of micro machining process using conventional and micro wire electrical discharge machining (WEDM) for fabrication of miniaturized components. Seventeen toothed miniaturized spur gear of 3.5 and 1.2 mm outside diameter were fabricated by conventional and micro WEDM respectively. The process parameters for both conventional and micro WEDM were optimized by preliminary experiments and analysis. The gears were investigated for the quality of surface finish and dimensional accuracy which were used as the criteria for the process evaluation. An average surface roughness (R a ) of 50 nm and dimensional accuracy of 0.1-1 µm were achieved in micro WEDM. Whenever applied conventional WEDM for meso/micro fabrication, a R a surface roughness of 1.8 µm and dimensional accuracy of 2-3 µm were achieved. However, this level of surface roughness and dimensional accuracy are acceptable in many applications of micro engineering. A window of conventional WEDM consisting of low energy discharge parameters is identified for micromachining.

In obtaining the best quality of engineering parts, the quality of machined surface plays an essential role. The fatigue strength, wear resistance, and corrosion of workpiece are some of the aspects of the qualities that can be improved. This paper investigates the effect of wire electrical discharge machining (WEDM) process parameters on surface roughness and kerf on stainless steel using distilled water as dielectric fluid and brass wire as tool electrode. The selected process parameters are voltage open, wire speed, wire tension, voltage gap, and off time. Empirical models using Taguchi method were developed for the estimation of surface roughness and kerf. The analysis revealed that off time has major influence on surface roughness and kerf. The optimum machining parameters for minimum surface roughness and kerf were found to be 10 V open voltage, 2.84 µs off time, 12 m/min wire speed, 6.3 N wire tension, and 54.91 V voltage gap.

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In Wireless Sensor Networks which are deployed in remote and isolated tropical areas; such as forest; jungle; and open dirt road environments; wireless communications usually suffer heavily because of the environmental effects on vegetation; terrain; low antenna height; and distance. Therefore; to solve this problem; the Wireless Sensor Network communication links must be designed for their best performance using the suitable electromagnetic wave behavior model in a given environment. This study introduces and analyzes the behavior of the LoRa pathloss propagation model for signals that propagate at near ground or that have low transmitter and receiver antenna heights from the ground (less than 30 cm antenna height). Using RMSE and MAE statistical analysis tools; we validate the developed model results. The developed Fuzzy ANFIS model achieves the lowest RMSE score of 0.88 at 433 MHz and the lowest MAE score of 1.61 at 433 MHz for both open dirt road environments. The Optimized FITU-R Near Ground model achieved the lowest RMSE score of 4.08 at 868 MHz for the forest environment and lowest MAE score of 14.84 at 868 MHz for the open dirt road environment. The Okumura-Hata model achieved the lowest RMSE score of 6.32 at 868 MHz and the lowest MAE score of 26.12 at 868 MHz for both forest environments. Finally; the ITU-R Maximum Attenuation Free Space model achieved the lowest RMSE score of 9.58 at 868 MHz for the forest environment and the lowest MAE score of 38.48 at 868 MHz for the jungle environment. These values indicate that the proposed Fuzzy ANFIS pathloss model has the best performance in near ground propagation for all environments compared to other benchmark models

This paper presents effects of silicon carbide SiC powder concentration on micro EDM parameters on average surface roughness (Ra). The aim is to achieve minimum Ra value on titanium alloy (Ti-6Al-4V) machined with tungsten electrode for various level of concentration of SiC powder and discharge energy (E). By using two-parameter and four-level factorial design of experiment sixteen experiments were conducted. The measured surface roughness values were analyzed with input parameters using by Design Expert software. The minimum Ra value obtained was 0.75 µm for 16.8 g/L SiC powder concentration and 57.8 µJ energy discharge. The analysis of variance revealed that powder concentration is the most influential parameter.

Alumina is a non-conductive ceramic material which can meet the high demand of industrial applications due to its excellent physical and chemical properties. However, machining of alumina is not possible by using the conventional machining methods due to its inherent brittleness. Recently, electro-discharge machining has been used for structuring alumina with assisting electrode to initiate the spark between the conductive tool electrode and the non-conductive work piece material. However, the effects of process parameters on material removal rate and surface roughness have not been investigated to formulate mathematical models. This study dealt with developing models for material removal rate and surface roughness correlating three process parameters which are peak current, pulse-on time and gap voltage using response surface methodology. The models were verified with 7% error between the results of empirical models and the experimental values.

In this study, the feasibility of using an industrial fluidized bed furnace to perform low-temperature thermochemical treatments of austenitic stainless steels has been studied, with the aim to produce expanded austenite layers with combined wear and corrosion resistance, similar to those achievable by plasma and gaseous processes. Several low-temperature thermochemical treatments were studied, including nitriding, carburizing, combined nitriding-carburizing (hybrid treatment), and sequential carburizing and nitriding. The results demonstrate that it is feasible to produce expanded austenite layers on the investigated austenitic stainless steel by the fluidized bed heat treatment technique, thus widening the application window for the novel low-temperature processes. The results also demonstrate that the fluidized bed furnace is the most effective for performing the hybrid treatment, which involves the simultaneous incorporation of nitrogen and carbon together into the surface region of the component in nitrogen-and carbon-containing atmospheres. Such hybrid treatment produces a thicker and harder layer than the other three processes investigated.