Optimisation of Tool Path for Improved Formability of Commercial Pure Aluminium Sheets during the Incremental Forming Process

An axisymmetric dome of 70 mm in diameter and 35 mm in depth was formed using the ISF process using varying proportions (25, 50 and 75%) of spiral (5) and helical (H) tool path combinations as a single tool path strategy, on a 2 mm thickness commercially pure aluminium sheets. A maximum forming depth of 30 mm was observed on all the components, irrespective of the different tool path combinations employed. None of the components were fractured for the different tool path combinations used. The springback was also same and uniform for all the tool path combinations employed, except for the 75S25H which showed slightly larger springback. The wall thickness reduced drastically up to a certain forming depth and increased with the increase in forming depth for all the tool path combinations. The maximum thinning occurred near the maximum wall angle region for all the components. The wall thickness improved significantly (around 10-15%) near the maximum wall angle region for the 25S75H combination than that of the complete spiral and other tool path strategies. It is speculated that this improvement in wall thickness may be mainly due to the combined contribution of the simple shear and uniaxial dilatation deformation modes of the helical tool path strategy in the 25S75H combination. This increase in wall thickness will greatly help in reducing the plastic instability and postpone the early failure of the component.