Considering its low-cost equipment, single-point incremental forming (SPIF) can be appropriate for rapid prototyping of sheet metal parts, since a simple hemispherical head tool is usually implemented without any dedicated dies. Incremental forming at elevated temperatures assisted by electric current, which is hereafter called resistance SPIF, is an innovative process for forming sheet metals with a high-strength-to-weight ratio and a low formability at room temperature. In the present research, the effect of utilizing various lubricants on both the formability and surface finish of the Ti–6Al–4V titanium alloy sheet is investigated using the resistance SPIF of the truncated cone at different feed rates, vertical pitches, and currents. To this end, the Taguchi design of experiment and the analysis of variance (ANOVA) are employed. A cooling water system is designed and applied to the forming tool to improve both its life and the duty cycle of the process. The results show that the formability of Ti–6Al–4V sheet can be enhanced using the resistance SPIF, which strongly depends on the lubrication condition. In order of significance, the lubricant and current have the most influence on the maximum achievable forming depth and the lubricant, the feed rate, and the vertical pitch have the highest effects on the surface roughness. Based on the ANOVA results, the graphite-based anti-seize compound and the graphite powder are suggested for an appropriate surface finish and the highest formability, respectively, in the resistance SPIF within the range of the considered parameters.
Single-point incremental forming High temperature Resistance heating Lubricant Formability
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The authors declare that they have no conflict of interest.