An experimental investigation of dimple effect on the stribeck curve of journal bearings

The friction characteristic of a journal bearing with dimpled bushings manufactured using the machining and the chemical etching techniques is investigated. A series of experimental results is presented to examine the effect of dimples on the Stribeck curve. Load, oil type, dimple size, depth and shape are varied to explore their influence on the friction characteristics. It is shown that with proper dimensions of dimples, the friction performance of journal bearings can be improved, particularly for light oils. The results reveal that in mixed lubrication regime, the so-called secondary lubrication effect in the dimpled area is the main mechanism responsible for improvement of performance. Experimental results also indicate that a bushing with etched dimples over the entire circumference offer a better frictional performance than a bushing with dimples etched on half of its circumference.