Accuracy and finish during wire electric discharge machining of metal matrix composites for different reinforcement size and machining conditions

Abstract

Electric discharge machining (EDM) has been established as an effective alternative process to conventional material removal processes for machining reinforced metal matrix composites (MMCs). Wire cut EDM holes were produced in a MMCs (10 vol% of SiC in 6061 Al), which were then investigated to determine the machinability of the material using this process. It was observed that the input factors such as the size of reinforced particles, wire tension, and pulse on time, significantly affect diameter error, circularity and surface roughness. Pulse on time, the interaction between pulse on time and wire tension contribute to the maximum diameter error. The wire tension is the most significant factor to circularity, which is followed by the interaction between pulse on time. In particular, wire tension with low and high tensions results in poor circularity. It has been found that there are more surface defects encountered when particle sizes are smaller, and circularity is improved when particles are in a medium size. In addition, the surface defect is reduced as the particles increase the melting resistance of the surface. The higher pulse on time leads to higher heat and more time to degrade the surface. Therefore, low pulse on time and wire tension gave better surface finish.

Understanding the wire electrical discharge machining of Ti6Al4V alloy

“…To avoid these aforementioned complexities during tradition machining, no-traditional machining such as WEDM is a common alternative towards the machining of titanium alloys. During WEDM, the workpiece is sunken in dielectric fluid to generate a favourable surrounding for electric spark formation to take place [5, 6, 7]. During the process, spark erosion occurs in the neighbourhood of electrodes and form anticipated two/three dimensional shapes based on input process variables by melting/evaporating the workpiece [8, 9].…”

Processing of duplex stainless steel by WEDM

“…However, this high heat also removes the wire material and easily deforms the circular cross-section of wire to oval shape which in turn reduces the KW [8]. The final KW accounts these two facts and it reduces with the rise of PONT initially followed by a decrease with the more upsurge of PONT when the constant parameters are high [27]. There is an optimum PONT for which the kerf width is minimum in this case.…”

Residual stress generation in metal matrix composites after cooling

“…These are some properties that are essential for the materials to be considered for number of structural applications such as drive shafts, bicycle frames, brake disks, diesel engine pistons and suspension components for vehicles and heavy industrial equipment (2). MMCs were developed to fulfil the ever increasing challenges of modern technologies as well as to overcome the limitations of conventional materials' properties (3). Reinforcements in MMCs may be discontinuous i.e., in the form of short fibres, whiskers or particulates; or continuous i.e., in the form of long fibres.…”