Studies on abrasive waterjet machining of black granite through design of experiments

Abrasive waterjet machining is emerging as an effective machining technique. In this context, optimizing the process parameters for effective utilization is essential. This paper discusses the machining of black granite with the use of a design of experiments approach and includes establishing the response equations. The influence of P, TR, and AFR for specially formulated abrasive samples having three different abrasive particle size distributions are analysed on the target parameters namely top kerf width, bottom kerf width, and kerf taper. At the 1% significance level, the top kerf width is influenced by high traverse rate and includes an interaction effect P × AFR. The bottom kerf width is influenced by abrasive sample AS3, and a high traverse rate TR3. Fragmentation of abrasives at the nozzle exit is higher due to the presence of larger size particles in the sample AS3. The interaction effects P × AS, AFR × AS, and PL × ASL are also found to yield minimum kerf width at the bottom. This is in addition to the jet instability influencing the bottom kerf width considerably. In the case of kerf taper, no parameters are clearly dominant at the 1% significance level, though kerf taper appears to be affected by a combination of all the independent parameters taken together. However, TR, TRL, and TRq are found to be significant at the 5% level. The response equations developed in this study will be useful to the manufacturing engineers to select a suitable combination of parameters for a specific application of black granite cutting. The numerical values reported in this study are specific to the cutting of black granite. Research with other types of granite is planned.