A selection methodology for the evaluation of lubricating oil performa
nces has been developed in order to help engineers in the definition o
f the right lubrication strategy. The methodology is exposed through a
cold forward extrusion process with a 75% reduction in area. Specific
friction tests are performed according to the physical and mechanical
contact conditions characterising the extrusion process. Four lubrica
ting oils available on the market are investigated. Three criteria are
proposed to characterise the performances: the friction coefficient,
the occurrence of two types of surface defects, and the resulting roug
hness of the specimen. The tribological behaviours are related to the
physicochemical characteristics of lubricating oils. Moreover, the rea
ction mechanisms of the different additives and the influences on the
regimes of lubrication are discussed. Finally, the optimum lubricating
oil with regards to the forward extrusion process is selected. (C) 19
98 Elsevier Science S.A.