EDM-Induced Areal Surface Topography and Recast-Layer Characteristics of Cu-Ni-Si-Cr Alloy Ampcoloy 944

Beryllium-copper alloys are extensively utilised across various industries due to their excellent mechanical and electrical properties. Beryllium-copper alloys can pose occupational health hazards when manufacturing operations generate airborne beryllium containing dust or fumes. Beryllium free copper alloys such as coppernickel- silicon-chromium (Cu-Ni-Si-Cr) are gaining popularity because they possess comparable properties to traditional beryllium copper alloys while eliminating the health risks associated with this specific exposure source. These non toxic alloys can serve as an alternative to traditional beryllium-copper in various engineering applications. Cu-Ni-Si-Cr alloys are rapidly being researched for application in the advanced materials of renewable energy technologies, die and mould making, electrical devices, electronics components, etc., particularly where thermal conductivity, electrical conductivity, corrosion resistance, and mechanical strength are essential. Electrical discharge machining (EDM) can be effectively utilised in machining hard materials, including beryllium-free copper alloys. The generated surface topography plays a significant role in the majority of applications for these alloys. Therefore, the analysis of the topography of machined surfaces of these alloys is critical. However, research on the EDM of these alloys has been limited. In this study, samples of the berylliumfree copper alloy have been machined using various combinations of input parameters, including the type of electrode, pulse-on time, pulse-off time, and polarity. The generated surface topographies have been analysed using a three dimensional (areal) surface profilometer by considering 23 selected areal surface texture parameters, providing spatial information beyond a single two dimensional roughness profile. These selected geometric indicators are discussed in relation to their potential functional applications. Scanning electron microscopy (SEM) analysis is performed specifically to measure the recast layer thickness of the selected samples below the machined surface. Analysis of variance is used to determine whether the selected input parameters significantly influence the responses. The results of the work show that the obtained Str values exhibit relatively weak directional anisotropy, and the degree of isotropy varying with experimental conditions. Three-dimensional roughness parameters are primarily influenced by polarity and the electrode material. The impact of pulse-off time on surface topography is minimal. Scanning electron microscopy of three selected samples indicates that the observed recast layer thickness increased with surface roughness. It offers a descriptive comparison rather than a generalised statistical correlation. Overall, the results establish a foundational understanding of the EDM induced surface topography and recast layer characteristics of Cu-Ni-Si-Cr alloys for advanced engineering applications.