Incremental Forming with Local Induction Heating on Materials with Magnetic and Non-magnetic Properties

Incremental sheet forming (ISF) is an agile process for small batch and rapid prototype production. Its hot variant has been developed because forming at elevated temperature increases the formability of materials and improves the accuracy of the worked parts reducing spring-back effects. Several hot ISF variants have been proposed reaching local or global heating. Here, a local heating solution has been presented by means of an induction system. This is done by a medium-high frequency generator and a heating head, continuously water cooled. The heating head, placed under the sheet and linked axially to the punch movement, warms the material locally generating eddy current in it. A laser pointer, focused on the sheet and following the punch movement, drives the generator in maintaining the desired temperature during the incremental forming phase. The first experimental trials were planned with the aim to investigate the process feasibility for forming magnetic (carbon steels) and non magnetic (titanium alloys) characterized by different forming and mechanical properties. Steel was chosen because it is a magnetic material and offers a natural resistance to the rapid change of the magnetic fields producing additional heat by hysteresis. For this reason, steel is a suitable material for the proposed heating solution. Furthermore, the effectiveness of the proposed heating system was tested on a titanium alloy, i.e. Ti6Al4 V, selected because being not nonmagnetic is more difficult to heat by induction. In conclusion, first results were presented showing the applicability of the designed solution as an ISF variant. This solution can be used for improving the formability of materials hard to work at room temperature.