A Study on the Die-Sinking Micro-Electrical Discharge Machining of EN-24 Die Steel Using Various Electrode Materials

Micro-EDM is an extensively used machining process for the fabrication of micro-holes with various advantages resulting from its characteristics of non-contact and thermal process. In this micro-fabrication technique, processing parameters greatly affect processing efficiency and stability. An experimental investigation on die-sinking Micro-EDM of EN-24 die steel using various electrodes such as tungsten, copper, copper tungsten and silver tungsten has been carried out. The present study aims to assess the quality and accuracy of the produced micro-holes, machining stability, material removal rate (MRR), tool wear ratio (TWR), surface roughness (Ra), Heat affected zone (HAZ) and overcut (OC). In addition, the influence of gap voltage, capacitance and discharge energy on the performance of the process has also been investigated. Experimental results proved that the overall performance of the copper electrode is found to be optimum with high MRR, thin HAZ though copper shows higher TWR, surface roughness and overcut.</jats:p

Multi-Criteria Optimization Using Grey Relational Analysis in Drilling of Glass/Epoxy Polymeric Composites

Glass Fibre Reinforced Polymeric (GFRP) composite materials have been used to make several components in engineering field. This is due to their excellent mechanical properties such as high specific strength, specific stiffness, good fatigue resistance, good corrosion resistance and light weight. Drilling is the process required for these composite materials for fitting and assembly with base part which may generate delamination at entrance and exit. In drilling of GFRP composite, delamination is one of the major defect which is more responsible for the rejection of components in the final assembly of engineering parts. An experimental investigation of full factorial design performed on drilling of Glass Fibre Reinforced plastic laminates using Helical flute straight shank drill and “Brad and Spur” drill by varying the process parameters such as cutting speed and feed rate to find the optimum drilling conditions. The main objective of this paper is to optimize the drilling process parameters with consideration of multiple performances such as specific cutting pressure, power, peel-up delamination factor and push-out delamination factor. Analysis of variance (ANOVA) was carried out for estimating the percentage contribution of process parameters on drilling performance. Grey relational analysis was used in this multiple objective optimization to get damage free drilling of GFRP composite. Response table and graph are used for this analysis which shows that feed rate is the most significant factor than the cutting speed and also it indicates that delamintation free drilling can be obtained at low feed rate and low cutting speed. The result shows that drilling performance can be enhanced effectively thorough this approach.</jats:p