Experimental study on the hole quality during abrasive waterjet drilling of CFRP

Abrasive Waterjet (AWJ) machining is considered an excellent alternative to conventional machining processes due to its superb machining characteristics. More specifically, Abrasive Waterjet drilling is nowadays a promising non-conventional process for obtaining high quality holes. In the present study, drilling experiments based on Taguchi L9 orthogonal design method were conducted via AWJ on carbon fiber reinforced polymer (CFRP) plate at various waterjet parameters, namely, different pressure, abrasive mass flow rate and standoff distance values. The purpose of the experiments was to investigate the impact of these process parameters on the quality of holes. The hole quality was determined by measuring the hole diameter error as well as the hole taper. The optical evaluation was implemented with the use of optical microscope and special measuring software. The ANOVA analysis of the results showed a significant influence of standoff distance regarding the hole diameter error and a combined influence of waterjet pressure and standoff distance regarding the hole taper. Furthermore, the optimal process parameter values for the optimization of the hole diameter error and hole taper were determined. The hole quality in terms of defects appearance was also quantitatively inspected, through optical imaging.