Enhancing electrical discharge machining performance through employment of titanium nanopowder mixed dielectric and severe plastic deformation of electrode / Houriyeh Marashi

Electrical Discharge Machining (EDM) is one of the most promising techniques for machining high-hardness materials with geometrically complex shape, which is implemented in various industrial fields such as die and mold, aerospace and biomedical. Despite the advantages, tool wear, relatively low material removal rate and its adverse effects on surface quality limit the applications of this technique. In this thesis two techniques are employed to overcome EDM disadvantages. The first technique is the addition of powder to dielectric, namely Powder Mixed Electrical Eischarge Machining (PMEDM). The aim of this research is firstly to enhance the characteristics of AISI D2 steel surface machined with EDM through adding Ti nanopowder to dielectric under various machining parameters, including discharge duration and current. Then surface characteristics and machining productivity were investigated in terms of morphology, topography, surface cracks susceptibility and MRR. It was indicated that addition of Ti nanopowder to dielectric notably enhanced the surface morphology and surface roughness at almost all machining parameters owing to discharge dispersion. The highest improvement of around 23 and 24% in average and peak-to-valley surface roughness were attained at 1 A current and 100 μs discharge duration, respectively. Furthermore, surface elemental analysis signified negligible Ti deposition on the machined surface while the atomic concentration of Ti was increased around the crack areas. Secondly, a novel technique for enhancing EDM electrode is proposed to reduce the electrode wear in EDM, which is challenging to overcome specially when it comes to producing geometrically complex components. This technique entails a new approach for developing pure copper electrode using Severe Plastic Deformation (SPD) to enhance the machining characteristics during EDM. Equal Channel Angular Pressing (ECAP) is selected as the most popular SPD method to process EDM electrodes. The results emphasize that electrodes subjected to ECAP enhance workpiece accuracy by decreasing Volumetric Overcut (VOC) and increasing corner sharpness. It is also revealed that nanohardness enhancement following ECAP leads to lower TWR. Lastly, combination of these techniques have been employed to realize the mutual effect of these techniques, employment of Ti nanopowder mixed dielectric and ECAP treatment of electrode. It was revealed that addition of powder to dielectric in all machining conditions leads to enhancing the machined surface quality in terms of morphology and average surface roughness. In overall, ECAP treatment of electrode improve the corner sharpness of produced components, however, addition of powder to dielectric deteriorates this effect through increasing the dielectric ionization. Formation of droplets on the surface close to the cavity walls was reduced after employment of Ti nanopowder mixed dielectric or/and ECAP treatment of electrode. Furthermore, addition of powder to dielectric increase the TWR for original and ECAP-treated electrodes due to increasing the ionization of dielectric fluid and there is a negligible amount of Ti element deposited on the machined surface when employing either of electrode types

Wire Rupture Optimization in Wire Electrical Discharge Machining using Taguchi Approach

Wire electrical discharge machining (WEDM) is one of the most important nontraditional machining process that is well-known for cutting difficult to machine materials. The wire electrode along with machining parameters control the WEDM process. This research work focuses on optimizing WEDM parameters using Taguchi technique to minimize wire rupture. Experiments have been done using the L18 orthogonal array. Each experiment is repeated three times to ensure accurate readings of the wire rupture. The statistical methods of signal to noise ratio (S/N ratio) is applied to study effects of peak current, pulse width, charging time, wire speed, and wire tension on wire rupture. As a results, the peak current, pulse width, and wire tension have the most significant effect on wire rupture followed by charging time and wire speed. The developed analysis can be used in the metal cutting field to identify the optimum machining parameters for less wire rupture

Wire Rupture Optimization in Wire Electrical Discharge Machining using Taguchi Approach

Wire electrical discharge machining (WEDM) is one of the most important nontraditional machining process that is well-known for cutting difficult to machine materials. The wire electrode along with machining parameters control the WEDM process. This research work focuses on optimizing WEDM parameters using Taguchi technique to minimize wire rupture. Experiments have been done using the L18 orthogonal array. Each experiment is repeated three times to ensure accurate readings of the wire rupture. The statistical methods of signal to noise ratio (S/N ratio) is applied to study effects of peak current, pulse width, charging time, wire speed, and wire tension on wire rupture. As a results, the peak current, pulse width, and wire tension have the most significant effect on wire rupture followed by charging time and wire speed. The developed analysis can be used in the metal cutting field to identify the optimum machining parameters for less wire rupture

Enhanced surface roughness of AISI D2 steel machined using nano-powder mixed electrical discharge machining

Manufacturing geometrically complex components with high strength and high wear resistance is an essential requirement in fabricating heavy-duty industrial components. Electrical Discharge Machining (EDM) is a non-conventional machining technique with the potential to machine any conductive material regardless of hardness property. This experiment concentrates on Powder Mixed EDM (PMEDM), where a specific concentration of titanium powder is added to the dielectric. The effect of adding powder is investigated on machined surface roughness. It is revealed that for 120 µsec and 210 µsec spark durations, the impact of titanium particles significantly improves the Ra and Rz of the AISI D2 steel machined surface. However, increasing the spark duration to 340 µsec leads to surface roughness deterioration owing to debris particles adhering onto the surface

White layer thickness prediction in WEDM-ANFIS modeling

<p>Wire Electric Discharge Machining (WEDM) is a nontraditional technique by which the required profile is acquired using spark energy. Regarding wire cutting, precision machining is necessary to achieve high product quality. White Layer Thickness (WLT) is one of the most important factors for assessing superior surface finish. In this research, Adaptive Neuro-fuzzy Inference System (ANFIS) was used to predict the WLT in WEDM using coated wire electrode. The predicted data were compared with measured values, and the average prediction error for WLT was 2.61 %.</p