Optimization of processing parameters and surface roughness of metallic sheets plastically deformed by incremental forming process

Single point incremental sheet forming (SPIF) is a process of manufacturing parts that leads to low prices of manufactured parts and high productivity. However, surface finish and forming time are responses that still need to be optimized to get better surface quality and less forming time. In the present paper, two techniques, the Taguchi grey relational analysis (TG) and response surface methodology (RSM), are combined together in order to get an optimal combination of several process parameters, such as the step increment, the feed rate, the rotation speed, the lubricant, and the sheet material. The cost function takes into account the response parameters such as the forming time, the axial, and the radial force, as well as the surface roughness in the sheet plane. The obtained results of this combination of techniques predict the grey relational grade by an empirical model that could be used in further experiments. Furthermore, the analysis of variance (ANOVA) for the grey relational grade is conducted to obtain the best levels of input process parameters.