Experimental Investigation on Geometric Accuracy and Surface Roughness of Formed Part in Multistage Single Point Incremental Forming (SPIF) Process

Abstract

Single point incremental forming (SPIF) process is an advanced dieless sheet metal forming process in which the requirement of a dedicated punch-die setup is eliminated. The dedicated punch-die setup is replaced by a universal blank holding fixture, a punch (or tool), and a backing plate. It has a variety of applications ranging from automotive to biomedical fields. But its limitations such as inability to form steeper wall angle and high geometric error in single-stage restricts its application in sheet metal industries. To overcome this, multistage SPIF process is an alternative to achieve larger wall angles. Formability in multistage SPIF process is increased by providing intermediate stages. Various methodologies have been suggested to enhance the profile accuracy, however, it still remains the major issue. In the present paper influence of process variables namely feed rate, number of forming stages and pitch size on geometric accuracy and surface roughness of formed part is investigated. Taguchi L18 orthogonal array is used for design of the experiments. From the analysis of variance (ANOVA), it is found that the number of stages and pitch size have a significant influence on geometric accuracy and surface roughness. Since feed rate is an insignificant parameter. So a higher feed rate can be used to reduce forming time. Further, a mathematical model is developed to predict the geometrical accuracy and surface roughness of the formed part.