Study on delamination factor and surface roughness in abrasive water jet drilling of carbon fiber-reinforced polymer composites with different fiber orientation angles

Carbon fiber-reinforced polymer (CFRP) composites are used in aerospace applications because of their superior mechanical properties and light weight. Avoiding damage in the machining of CFRP composites is difficult using traditional methods. Abrasive water jet (AWJ) has recently become one of the preferred machining methods for CFRP composites. This study evaluated the AWJ machinability of CFRP composites having three different fiber orientation angles (M1: [0 degrees /90 degrees ]s, M2: [+45 degrees/- 45 degrees ]s, and M3: [0 degrees /45 degrees /90 degrees/- 45 degrees ]s) according to the delamination factor (D-f), and the average surface roughness (R-a) as quality characteristics of the drilled holes. The aim of the study was to investigate the effects of different levels of AWJ drilling parameters on the delamination factor and surface roughness and to determine the optimum drilling parameter levels that provide minimum delamination formation and surface roughness values. For this purpose, AWJ drilling experiments were carried out using the Taguchi L16 (4(4)) orthogonal array. Water pressure (WP), stand-off distance (L), traverse feed rate (F), and hole diameter (D) were chosen as process parameters. Analysis of variance was used to determine the percentage effects of the AWJ drilling process parameters. The microscopic surface roughness and delamination formation properties of the machined surfaces were revealed using a scanning electron microscope and an optical microscope, respectively. The most effective parameters on D-f and R-a in the AWJ drilling of M1, M2 and M3 CFRP materials were determined to be water pressure, and stand-off distance. Minimum D-f and R-a values were obtained when AWJ drilling the M3 CFRP composite with a fiber orientation angle of [0 degrees /45 degrees /90 degrees/- 45 degrees ]s. Minimum delamination formation and very good surface quality can be obtained when the optimum process parameters determined in this study are used in the planning process for the AWJ drilling of CFRP composites having different fiber orientation angles.