Proposal of lubricant test for thick sheet forming

The purpose of this research is to develop a new method for the evaluation of lubricant performance with regard to the plastic deformation forming of thick sheets. A series of procedures for the new method are described and the feasibility of the method confirmed. Attention is focused on the compression of a disk-shaped blank by a ring-type punch, and the formation mechanism of the 'dome' that is generated in the center of the blank. This mechanism is assessed by considering a nomograph (constructed through rigid plastic FEM analysis), and the height of the dome is related to the friction coefficient. In an experimental approach, the disk and ring-punch compression tests were performed with 5 types of lubricant, the actual friction coefficients being obtained from a nomograph.