3. Experimental setup
Ball-on-disc experiments were conducted under oil lubrication
condition at room temperature (25 °C) using the self-designed
experimental rig (Fig. 2). The friction force signal was obtained by
a force sensor mounted on the rig. OLVF was used to monitor and/
or assess the wear processes in the sampling period of every
5 min. The lubrication oil was drawn from an oil vessel and
squeezed into the contact surfaces between ball and disc specimens
by a peristaltic pump. Oil sample drawn from the oil pool
flowed through and was detected by OLVF in monitoring section.
Captured ferrograph images were then transferred to a PC system
where the ferrograph images were then processed to obtain their
corresponding IPCA values.
3.1. Experimental condition
White mineral oil with kinematic viscosity of 28.5–35.2 mm2
/s
was used as the lubrication oil, and was fed with a feeding rate of
only 1.3 ml/min so as to wet the friction surfaces as required in the
tests. The tests were performed with disc rotating speed to be
150 rpm that gave a relative sliding velocity of 0.35 m/s to avoid
the occurrence of elasto-hydrodynamic lubrication, and the ball
slid on the disc with the diameter of 40 mm. The relevant surface