The objective of this paper is to investigate the influences that geometry,
roughness of the sensor system and gap size exert on the rheological measu
rements of a commercial lubricating grease. With this aim, creep and stress
growth experiments, stepped strain rate ramps and dynamic measurements wer
e performed using different geometries and roughness. A significant influen
ce of gap size was found in transient and steady-state experiments in a cer
tain range of strain rate. Roughening the surface of the geometry increases
considerably the values of the stress in comparison to the measurements pe
rformed with smooth surfaces. The experimental results are discussed taking
into account the wall slip phenomenon. In addition to this, different groo
ves made in the surfaces of the tools seem to eliminate or considerably dec
rease these wall slip effects. However the influence of geometry or roughne
ss was not detected in oscillatory tests performed inside the linear viscoe
lastic range.