The cylindrical surface characteristics of AA7075 aluminum alloy machined by abrasive waterjet with circular cuts

Abstract

Abrasive waterjet (AWJ) is an untraditional machining tool that has been used in numerous applications. This study aims at clarifying the cylindrical surface characteristics machined by AWJ under different radii (Rc) of circular cuts. AA7075 aluminum alloy was used as the specimen, and the morphologies and roughness of the cut surfaces were used to evaluate the cutting quality. The main processing parameters include the working pressure, the tangential velocity, and the standoff distance. Additionally, a linear cut under the same parameters was conducted for comparison. Results show that linear and circular cuts share the same material removal mechanism, but the quality of cylindrical surface is worse than that of the plane one. Roughness in all the three regions gradually increases with the decrease of Rc and varies the most in the rough zone. The roughness at the bottom of the workpiece with Rc = 2.5 mm is more than twice that of a linear cut. The micro-morphologies of the surfaces are distinctly different under various Rc, and the jet lag effect is more obvious at smaller Rc. The analysis result of variance (ANOVA) showed that the ranking of prominent parameters affecting the cylindrical surface quality are the tangential velocity, the circular cut radius, the working pressure, and the standoff distance. To achieve a high cutting quality when using AWJ for circular cuts, it is recommended to prioritize optimizing the tangential velocity. Furthermore, the regression model of input parameters and roughness was developed, whose mean error and correlation coefficient R2 were 5.51% and 0.9489, respectively.

Keywords

• Abrasive waterjet
• Circular cut
• Surface roughness
• Cylindrical surface
• Machining parameters