Incremental sheet forming of aluminum alloy using a hemispherical-end tool heated by electromagnetic induction

Abstract

An experimental study on an induction heat-assisted incremental sheet forming (IHAISF) of AA6061-T6 aluminum alloy was carried out. The novelty of this work is that the heating of the tool is carried out instead of the sheet, which is a simple and efficient procedure. This method enables a better-localized temperature control to enhance formability, reduce flow stress, and improve surface finish. The effect of tool diameter, temperature, feed rate, the rotational speed of the tool, and step height on the formability, surface integrity, and sheet thinning was studied. Surface morphology and elemental composition were studied using optical and scanning electron microscopy with energy dispersive spectroscopy. Larger tool diameters and higher temperatures yielded a superior surface finish, whereas increasing feed rate, spindle speed, and step depth increased surface roughness. Localized heating significantly improved the formability of this aluminum alloy, which normally showed poor formability at room temperatures due to its limited ductility. A major strain of 0.465 could be achieved without fracture at a tool temperature of 150 °C, while a crack-free smooth surface was obtained at a tool temperature of 250 °C in the presence of a solid lubricant. Thus, this experimental study demonstrated the potential of a novel IHAISF for forming of difficult-to-form materials with a simplified heating arrangement.