An Experimental Investigation of Curved Surface-Straight Edge Hemming

In this paper, an experimental investigation of the curved surface-straight edge hemming process is presented. Because hemming is the last stage of automotive panel forming operations, it directly influences the product surface, fitting, and joining qualities. Dimensional accuracy and precision in shape are two major concerns of hemmed parts, and these concerns are usually influenced by a large number of material, geometrical, and process factors. Planned experiments have been carried out according to a fractional factorial design method. Through regression analysis of the experimental results, the hemming quality indices, such as creepage, recoil, and radial springback, as well as hemming loads, can be expressed as a weighted sum of the input variable effects. In addition, the magnitude of each effect can be ranked from the most to the least significant. Using this information, hemming design guidelines can be developed for the optimization of hemming processes.