Traditional stamping technologies that sandwich sheet metal between a die and punch have several inherent limitations such as the use of heavy tools, localized deformation that damage the parts and inhibit consistency. High speed forming is a light weight tooling assembly that forms the part without using any punch. Electromagnetic forming (EMF) is one among the gamut of high speed forming technologies that is used for embossing fine surface features onto sheet metals. This work investigates the dynamics of sheet metal impact through a simulation study. The primary objective of this work is to develop a modelling facility that guides experimental design of flat ridged parts. Critical factors that influence the product quality are investigated. The high impact energy translates into an appreciable rebound that affects the product shape. Interface conditions play a critical role in influencing the shape of the final part. Contrary to intuition, friction is beneficial in high speed forming unlike traditional stamping where friction leads to tearing of sheet metal. Shape fidelity is investigated through a prototypical study of the expansion of a round tube into a square hole.
Traditional modelling techniques solve a coupled system of equations with spatially varying electromagnetic fluxes controlling the dynamics of the plastic deformation. Because the magnetic pressure is spatially uniform, the flux equations are obviated from the coupled system rendering them computationally efficient. The calibration of contact mechanics that influence the rebound behaviour of the sheet metal remains as a difficult issue. The interfaces between various sheet metals and the metal die play a critical role in controlling the shape of the final product. The characterization of such an interface using appropriate calibrated friction coefficients is assessed. The role of magnetic pressure in reducing the sheet metal rebound is demonstrated via a comparison between results from mechanical and electromagnetic simulations. The influence of the channel geometry on final shape is illustrated through simulations and experiments.