Simulation and Experimental Observations of Effect of Different Contact Interfaces on the Incremental Sheet Forming Process

Incremental sheet forming (ISF) is a promising forming process perfectly suitable for manufacturing customized products with large plastic deformation by using a simple moving tool. Up to now, however, the effects of contact conditions at the sheet interface are not well understood. The aim of this work is to study the effect of tool type and size on the formability and surface integrity during the forming process. Experimental tests were carried out on aluminum sheets of 7075-O to create a straight groove with four different tools (phi 30,phi 25.4,phi 20 and phi 10mm). One tool tip was fitted with a roller ball (phi 25.4mm) while the other three were sliding tips. The contact force, friction and failure depth were evaluated. A finite element (FE) model of the process was set up in an explicit code LS-DYNA and the strain behavior and thickness distribution with different tools were evaluated and compared with the experimental results. This study provides important insights into the relatively high formability observed in the ISF process. Microscopic observations of the surface topography revealed that a rolling tool tip produced better surface integrity as compared with a sliding tool tip, wherein, distinct scratch patterns in the tool traverse direction were evident.