Lubrication With Emulsion in Cold Rolling

Petroleum oil-in-water emulsion, where water is the continuous phase, is often employed under circumstances where the high heat capacity of water is beneficial while the poor lubricating properties of an oil-in-water emulsion can be tolerated. Usage includes cold-rolling but also some hot rolling applications. However, emulsions do not exhibit Newtonian behavior even when their individual components themselves are Newtonian, thus classical lubrication theory is not valid for these applications. In this paper we employ the extended Reynolds equations of Al-Sharif et al., derived for binary mixture lubricants, to study strip-rolling lubricated with oil-in-water emulsion. We are able to predict several experimentally observed phenomena such as oil-pooling, enhancement of oil-pooling with increased strip yield stress and with increased roller speed.