Grease soap particles passing through an elastohydrodynamic contact under side slip conditions

In a previous investigation, grease thickener fibres were tracked as they p assed through an elastohydrodynamic (EHD) contact in pure rolling using int erferometry in a standard ball-and-disc apparatus. In order to capture sing le thickener fibres, a high-speed video camera was used. Here, the experiments have been repeated introducing different amounts of s ide slip for different rolling speeds and a faster video camera capable of capturing 4500 frames/s. The contact was lubricated with a continuous suppl y of grease. Two greases, based on the same synthetic poly(a-olefin) but th ickened with Li-12-OH and lithium complex soap respectively, were studied. It was observed that the thickener fibres were stretched both before enteri ng the contact and as they passed through it. Fibres seem to avoid the mini mum film thickness regions and, if they enter, the film is restored immedia tely after passage.