Chasing the Magic Wear Rate

The magic wear rate (MWR) is the rate of wear at which any rolling contact fatigue cracks that are in initial stages of development are removed either by natural or a combination of natural and artificial wear. It is a simple concept which recognizes that when there is little or no wear, the rail will usually fail as a result of contact fatigue, but when there is excessive wear, the life is unnecessarily wasted. The concept has direct application to rail maintenance practices, in particular rail grinding. This paper details the basic theory of the magic wear rate and includes a discussion about the impact of various influencing factors including wheel load, friction, track curvature and metallurgy. Application is made chiefly to rail grinding, although it is acknowledged that the principle also extends to wheel wear. Examples of current practices are given and a new approach to rail grinding is presented that would better target the magic wear rate.Peer reviewed: YesNRC publication: Ye