Effect of temperatures during forming in single point incremental forming

In this article, the temperatures at sheet-tool interface are observed with non-contact temperature sensors in single point incremental forming at high relative tool velocities. A flat-ended tool was used to form AA5754-H32 sheets, and the results were recorded to study the heat generation from relative tool motion over the sheet metal surface. This paper proposes a new geometry to study the effects of temperature on formability and resulting geometrical errors. The regions of large geometrical errors are presented in cross-sectional and isometric views in colour contrasts. As the tool moves along a prescribed path, a moving comet type temperature structure is observed with two heat generation zones for the first few step downs. The resulting microstructures are observed for each of the following cases and the disparities are reported. Generally, the blankholder is assumed to be at a constant temperature. Results show this is not true; the actual temperature rises with a heat loss to the blankholder via backing plate. High rotation speeds are used, with an upper limit being observed, before forming of sheet metal becomes untenable. At this limit, high wear followed by lubricant fuming is observed. The result at higher rotational speeds is similar to friction stir welding, which are explained in detail by the microstructures. Surface roughness of the formed components as a response to the high tool linear speeds with flat tools is also presented.