Hydrodynamic lubrication of deep drawing

An isoviscous steady hydrodynamic lubrication model for a deep drawing process is developed. Equations to calculate lubricant film thickness, radial, and drawing stresses are presented. The die inlet film thickness is related to the properties of the lubricant and the sheet metal, the tooling geometry and the operating conditions. A series of experiments with low carbon steel sheet blanks and different types of lubricant was conducted. The formation of a thick hydrodynamic lubricant film associated with a matt surface finish was observed for using certain lubricants. In each experiment, the thickness of the lubricant film was estimated from the difference in diameter between the lubricated and unlubricated drawn cups. The experimental measurements of lubricant film thickness and drawing force were compared with values calculated from the theoretical model. There is some degree of agreement between these results