An Investigation into Piston Ring Scuffing During Running-In

The investigation concerns the influence of lubricants, materials, and surface finish on scuffing failure employing a special test rig and a high speed, single cylinder, engine. The rig, which was used to gain closer control and ease of observation, reproduces characteristic scuffing and has defined a range of performance in terms of contact load, ring velocity and liner temperature. Trends in performance are found to correlate with service experience and a “performance-factor” has been derived relating median failure loads for various speeds. Confirmation of rig results is being obtained in the engine in terms of operating conditions of ring velocity and ring contact load defined by the “performance-factor”.