Experimental Investigation of Elevated Temperature Single Point Incremental Forming of AA6061 Aluminum Sheet

Single point incremental forming is a cost-effective process with high flexibility and as a result, would be a proper selection for low-batch and high-customized production compared to traditional processes such as pressing. The target market of this process usually consists of medical, automotive, and aerospace industries in which metals with high strength to weight are highly in demand. These materials are usually formed at elevated temperatures due to their low formability at room temperature. In this study, the AA6061 aluminum sheet was homogeneously heated at 25-400°C. In addition, the effects of important process variables of heat-assisted SPIF including temperature, vertical pitch, feed rate, and three types of lubricants were investigated on formability of truncated cones with various wall angles. According to the results, despite the inability of local heating in enhancing the formability of the AA6061 sheet (37% improvement of formability under optimal conditions), the homogenous heating approach which was used in this article leads to a significant improvement in formability (528%). Temperature is the most important parameters effective on the formability, while lubricant and vertical pitch are ranked as the second and third parameters, respectively and the effect of feed rate is negligible. The critical wall angle increases from 60 to 65 degrees with increasing the temperature from 25 to 400°C. In order to choose a suitable set of parameters, the surface roughness should be taken into account, which may alter the results from 1.18 to 4µm as the best and worst surface conditions, respectively. Furthermore, a truncated cone with a wall angle of 65 degrees was successfully formed to 44mm depth using an appropriate combination of process parameters. This demonstrates an outstanding improvement in formability.