Investigation of Ecology Friendly Lubrication in High Speed Drawing Of SSID Tubes

Abstract

Tubes used in the chemical and fluid power industry have special inner surface roughness requirements. To meet these requirements, it was decided to explore the mandrel drawing of carbon steel tubes to submicron surface finish and thereby reduce the need for machining and honing the inner diameter of the tube. An additional goal was to investigate the use of ecology friendly solid lubricant in the mandrel drawing process. First, a roughness model was developed which relates the interface parameters such as effective stress to roughness changes and lubrication parameters. This model was calibrated using industrial experiments on a draw bench. Then a design of experiment was carried out to relate the tube drawing phenomenological parameters such as die angles, reduction and drawing speed to the interface parameters. These two models were then integrated to predict the surface roughness changes at the inner surface of the tube during mandrel drawing. It was found that the new lubricant is able to provide good surface finish for typical tube drawing reductions with and without the conversion coating. However, for reductions larger than 40% it cannot prevent die pick up. At drawing speeds greater than 0.5 m/s it is effective in preventing die pick up but cannot deliver SSID surface finish in drawn tubes.