The paper details a comprehensive experimental investigation on the influence of operating parameters and cut direction (parallel and perpendicular to fibre orientation) when wire electrical discharge machining (WEDM) unidirectional CFRP composites using zinc-coated brass wire (0.25-mm diameter). A Taguchi L18 fractional factorial orthogonal array considering four variable parameters including open voltage, ignition current and pulse-on time as well as pulse-off time was carried out for each cut direction. Results showed that a ~ 16% increase in maximum material removal rate was achieved when machining parallel to fibre direction (2.41 mm³/min) compared to cutting perpendicular to the fibres (~ 2.08 mm³/min), which was attributed to the higher electrical conductivity of the workpiece along the fibre length leading to greater discharge energies. This however resulted in relatively larger average kerf widths and poorer workpiece surface roughness (Sa) caused by the Joule heating effect. Workpieces machined parallel to fibre direction were generally free of any major edge defects, in contrast to severe delamination observed on both the top and bottom surfaces of specimens cut perpendicular to fibre orientation. High-magnification scanning electron microscopy of the machined surfaces revealed the presence of adhered resin material, fibre cracking, cavities/gaps in the matrix phase and interlayer cracks on most of the samples analysed, with damage severity dependent on the operating parameters and cut direction.

本文详细介绍了使用镀锌黄铜丝（直径0.25 mm）的电火花放电加工（WEDM）单向CFRP复合材料时，操作参数和切割方向（平行和垂直于纤维取向）的影响的综合实验研究。针对每个切割方向执行了Taguchi L18分数阶乘正交阵列，该阵列考虑了四个可变参数，包括开路电压，点火电流，脉冲接通时间以及脉冲断开时间。结果表明，在最大的材料去除速率的〜16％的增加达到加工时平行于纤维方向（2.41毫米³相比切割垂直于纤维（〜2.08毫米/分钟）³/ min），这归因于工件沿着纤维长度的较高电导率，导致更大的放电能量。然而，这导致相对较大的平均切缝宽度和由焦耳热效应引起的较差的工件表面粗糙度（Sa）。平行于纤维方向加工的工件通常没有任何主要的边缘缺陷，这与在垂直于纤维取向切割的样品的顶面和底面都观察到严重的分层相反。机械加工表面的高倍扫描电子显微镜显示，在分析的大多数样品上，存在粘附的树脂材料，纤维开裂，基体相中存在空隙/间隙和层间裂纹，损伤的严重性取决于操作参数和切割方向。