Modeling Cutting: Plastic Deformation of Polymer Samples Indented With a Wedge

Abstract

An experiment was designed to relate force to plastic deformation caused by a wedge indenting the edge surface of a polymer sample. The experiment reveals the primary phenomena observed in industrial converting processes of cutting and slitting of thin polymer films. The thin film was modeled using a polycarbonate rectangular block, which was indented with a metallic half-round wedge that represents the industrial cutter blades. The wedge radius and sample size were selected to scale to the ratio of slitting blade radius and industrial film thickness. A compression test frame impressed wedges into polymer samples with measurements of both force and displacement recorded. These experiments clearly revealed the shape of the plastic deformation zone ahead of and around the wedges. Data from the experiments showed increasing cutting force with wedge displacement until the sample fractured. Plastic deformation of the samples was examined: the out-of-plane plastic volume was shown to equal the volume displaced by the wedge. Cracks that developed from the side of the wedge tip during indention propagated with near steady-state loads under edge surface indention.