Experimental investigation on Cavitating Water Jet Incremental Forming (CWJIF): Parameter optimization and process window establishment

Abastract Lightweight thin-walled components are widely used in aerospace, automotive, and electronic industries, driving a persistent demand for flexible and high-precision forming technologies. This study conducts a systematic experimental investigation into a novel process of Cavitating Water Jet Incremental Forming (CWJIF) applied to AA5052 aluminum alloy sheets. The effects of nozzle structure and loading trajectory were evaluated. The key process parameters - namely water jet pressure, stand-off distance, feed rate, and incremental step - were further optimized using response surface methodology (RSM), and the typical forming defects were characterized to establish reliable process windows for varing sheet thicknesses. The results indicate that all four process paramters exert significant influences on the forming height, ranked in descending order of significance as follows: water jet pressure > stand-off distance > feed rate > incremental step. The optimal parameter set was determined as a stand-off distance of 65 mm, a water jet pressure of 20 MPa, a feed rate of 10 mm/s, and an incremental step of 1.2 mm. Under the optimized condition, the RSM-predicted forming height showed a relative deviation of only 3.8% from the experimentally measured value. Three typical failure modes—fracture, buckling, and interlaminar layering - were systematically revealed, based on which comprehensive defect-control process windows were established for sheets with thicknesses of 0.3 mm, 0.5 mm, and 0.8 mm, respectively. Overall, this work provides comprehensive experimental insights into CWJIF of AA5052 sheets and offers practically validated strategies for process optimization and defect control, serving as a reliable reference for industrial applications.