An Investigation of the Micro-Electrical Discharge Machining of Nickel-Titanium Shape Memory Alloy Using Grey Relations Coupled with Principal Component Analysis

Abstract

Shape memory alloys (SMAs) are advanced engineering materials which possess shape memory effects and super-elastic properties. Their high strength, high wear-resistance, pseudo plasticity, etc., makes the machining of Ni-Ti based SMAs difficult using traditional techniques. Among all non-conventional processes, micro-electric discharge machining (micro-EDM) is considered one of the leading processes for micro-machining, owing to its high aspect ratio and capability to machine hard-to-cut materials with good surface finish.The selection of the most appropriate input parameter combination to provide the optimum values for various responses is very important in micro-EDM. This article demonstrates the methodology for optimizing multiple quality characteristics (overcut, taper angle and surface roughness) to enhance the quality of micro-holes in Ni-Ti based alloy, using the Grey-Taguchi method. A Taguchi-based grey relational analysis coupled with principal component analysis (Grey-PCA) methodology was implemented to investigate the effect of three important micro-EDM process parameters, namely capacitance, voltage and electrode material.The analysis of the individual responses established the importance of multi-response optimization. The main effects plots for the micro-EDM parameters and Analysis of Variance (ANOVA) indicate that every parameter does not produce same effect on individual responses, and also that the percent contribution of each parameter to individual response is highly varied. As a result, multi-response optimization was implemented using Grey-PCA. Further, this study revealed that the electrode material had the strongest effect on the multi-response parameter, followed by the voltage and capacitance. The main effects plot for the Grey-PCA shows that the micro-EDM parameters "capacitance" at level-2 (i.e., 475 pF), "discharge voltage" at level-1 (i.e., 80 V) and the "electrode material" Cu provided the best multi-response.

Optimization of Scanning Parameters in Coordinate Metrology Using Grey Relational Analysis and Fuzzy Logic

“…It is especially useful when the experiments cannot be performed precisely and it aids to compensate the limitations in statistical regression [33]. The GRA can successfully be combined with other methods, such as PCA to enhance the quality of decision making [34]. In this study, the corresponding weighting values for GRA were obtained from the PCA.…”

Study on the Discharge Characteristics of Single-Pulse Discharge in Micro-EDM

“…Micro-electrical discharge machining (micro-EDM) has become one of the most popular microfabrication technologies due to the advantage of machining electrically conductive materials without direct contact [4][5][6]. Micro-EDM has been has attracted great attention from researchers and has been widely used in the micro-machining field [7][8][9].…”

Surface Integrity of Micro EDM Surface Using Electrodes of Various Diameters

“…As one of the most popular nontraditional machining methods, micro electrical discharge machining (micro EDM) has been proved to be qualified for the fabrication of various micro features [3]. Nowadays, micro EDM is used widely in advanced manufacturing area, such as medical industries, biotechnology, aeronautics, and astronautics [4][5][6].…”