Frictional behaviour of a greased contact under low sliding velocity condition

In greased contacts, the complex rheology of a grease, depending on thickener, base oil and additives, becomes key point for understanding controlling evolution friction coefficient at extremely low sliding velocities. Such velocity range (from 0 to few mm/s) is main relevance several issues, such as unstable friction-induced vibrations, which can occur well in case lubricated interfaces. this paper, contact velocities then reproduced analysed dedicated tribometer, under controlled boundary conditions. Static dynamic coefficients, function velocity, are obtained, considering either dry contact, with both grease its oil. The effect DLC surface coating too. contributions lubricant components frictional response have been discussed, showing non-trivial trend friction, respect speed, within investigated range.