Improving the cutting quality of aluminum alloy machined by abrasive waterjet with a relatively low pressure

The cutting quality of abrasive waterjet (AWJ) can be generally improved by increasing the pressure, but a higher pressure means a reduced service life of the equipment and increased manufacturing and maintenance cost. In order to obtain the required high cutting quality at a relatively low pressure of 150 MPa, the process parameters of AWJ were optimized using the response surface methodology (RSM). The surface roughness ( R a ) and the kerf taper ( K t ) were used to evaluate the cutting quality. The Central Composite Design (CCD) model was applied for designing the cutting experiment, and the effects of abrasive flow rate, standoff distance, and traverse speed on the machining quality were analyzed using the method of Analysis of Variance (ANOVA). By using the obtained optimal machining parameters of AWJ, the double-pass strategy was used to further promote the cutting quality. The results show that the cutting quality at the low pressure of 150 MPa can be significantly improved by optimizing the process parameters or increasing the number of cutting pass. The highest cutting quality of R a = 4.55 μm and K t = 0.149° can be achieved at a traverse speed of 33 mm/min, a standoff distance of 0.66 mm, and an abrasive flow rate of 339 g/min. Using the strategy of double-pass cutting, the R a can be reduced by a maximum of 82.74%, and the greatest reduction in K t is 59.94%, meaning the cutting quality is better when compared with that under the ultra-high pressure of 350 MPa with single-pass cutting.