Experimental and numerical study of forming aluminum stepped tubes by electromagnetic forming method

Challenges such as limited formability, high springback, and wrinkling in aluminum forming are addressed using electromagnetic forming (EMF), a high-speed technique that accelerates the workpiece for precise forming. This study investigates stepped tube production by EMF, experimentally and using Finite element simulation. A key focus is the detailed exploration of EMF for stepped tubes, resolving issues like uneven thinning and poor material flow. In this study, Aluminum 6063 tubes with a thickness of 0.95 mm were used. A coil was optimized in COMSOL by analyzing parameters such as the number of turns of the coil, wire spacing, and coil-to-workpiece distance to enhance quality. Additionally, implementing air venting channels in the die design eliminated dents and incomplete filling, enhancing production outcomes. Initial single-step tests at 4, 5, and 6 kV showed insufficient filling and excessive thinning, leading to the development of a multi-step approach. In addition, precise three-dimensional modeling with full coupling was improved simulation accuracy for complex geometries. Two-step and four-step methods overcame single-step limitations. Results confirmed that the two-step method at 4 kV and 6.5 kV achieved optimal outcomes, with a 30.67% expansion ratio and a 20% improvement in thickness distribution. An inverse analysis estimated the coefficient C in the Johnson-Cook model, enhancing material behavior predictions. These advancements address EMF challenges and offer opportunities for industries like automotive and aerospace.