Multidimensional evaluation of stepped hole EDM drilling in C_f/UHTCs components: Efficiency, performance, economic, and carbon emission

Electrical discharge machining (EDM) offers potential advantages for fabricating cooling holes in carbon fiber reinforced ultra-high-temperature ceramics (C_f/UHTCs) components. However, the alternating conductive and non-conductive nature of these materials, together with the requirement for a large number of holes, presents significant challenges regarding machining efficiency, electrode wear, energy consumption, economic cost, and carbon emissions. Nevertheless, current studies lack a comprehensive evaluation model that incorporates these sustainability factors over the full machining process. To address this challenge, this study proposes an EDM drilling method for stepped holes (STH) based on hole geometry optimization. A multidimensional evaluation approach was employed to assess the method in terms of machining efficiency, electrode wear, surface roughness, cooling performance, tensile strength, energy consumption, economic cost, and carbon emissions. Results show that compared to traditional straight hole II(SHII) single-hole machining, the STH method reduced machining time by 22 %, electrode wear by 20 %, and increased maximum cooling efficiency by 0.2 %, with only an 8 % reduction in tensile strength. Throughout the full machining process, the STH approach achieved 21.8 % reduction in energy consumption, 20.7 % decrease in total machining time, 25 % reduction in overall economic cost, and 22.2 % reduction in carbon emissions. These results demonstrate that the STH EDM drilling method has significant advantages for fabricating cooling hole in C_f/UHTCs. It enhances machining efficiency and reduces electrode wear, energy consumption, economic cost, and emissions while maintaining acceptable mechanical performance.