Surface Topography from Single Point Incremental Forming Using an Acetal Tool

Abstract

This paper investigates a new tool, where the forming tip is constructed from acetal. The acetal tip is investigated because it is self-lubricating and more compliant than traditional SPIF tools. This work characterizes the topography of surfaces created by forming aluminum with both the acetal-tipped tool and a carbide tool. When the parts are compared visually, the parts formed with the acetal tool maintain the appearance of the unformed sheet metal. The surfaces of the parts are measured using an Olympus LEXT OLS4000, a vertical scanning laser confocal microscope. Surface height as a function of lateral position on both sides of the parts (contact and free surface) is measured. These measurements are analyzed quantitatively using areal surface texture parameters and qualitatively compared with micrographs of the surfaces. Comparisons of the surfaces that are in contact with the tool reveal that the surfaces produced with the acetal tool are rougher but more isotropic than those produced using the carbide tool. The surfaces produced by the carbide tool have a more anisotropic appearance, which is created by the tool as it steps down to form the part. The benefit of using the acetal tool rather than the carbide tool is the absence of the anisotropy caused by tool step down. The free surfaces produced by both tools are much rougher than the surfaces that contact the forming tools, since the tool does not affect roughness of the free surfaces.