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.

Effect of stress relieving heat treatment on surface topography and dimensional accuracy of incrementally formed grade 1 titanium sheet parts

“…As observed by Ham et al [13] earlier, the orange peel effect can be attributed to the grain size and lattice structure. On subjecting the sheet to heat treatment, the increase in grain size results in an outer surface that has a reduced average surface roughness but higher anisotropy on forming.…”

“…It was also shown that SPIF could be done at high speeds, as a result of this work. Later, Ham et al [13,14] suggested that it was more useful to use areal surface texture parameters in evaluating surface texture and topography in SPIF and compared surfaces produced using two different types of tools, acetal, and carbide. It was found that the acetal tool produces rougher surfaces than the carbide tool, but with more isotropy.…”

Review on the influence of process parameters in incremental sheet forming

“…Therefore, some researchers tried to select the most suitable material and tool diameter to get a better surface finish. Ham et al [84] used two tools: one was acetal tipped, and the other was a carbide tool to characterize the topography of surfaces created by forming aluminium sheet. It was found that the Fig.…”

Residual Stresses and Surface Roughness Analysis of Truncated Cones of Steel Sheet Made by Single Point Incremental Forming

“…The main standard 3D parameters determined by this measurement are the average roughness Sa, the highest peak of the surface Sp, the root mean square roughness parameter Sq, and the maximum pit depth Sv. Selection of surface roughness parameters was based on the work of Ham et al [32,33] which suggested that it was more useful to use areal surface texture parameters in evaluating surface texture and topography in single point incremental sheet forming.…”