Preventive GrindingThe purpose of p

Preventive Grinding
The purpose of preventive grinding is to reduce maintenance work (and costs) and to ensure the safety
of vehicles through removal of potentially hazardous rail defects. In particular, the transverse cracks that
propagate from RCF defects can lead to broken rails. The preventive grinding approach is based on crack
initiation studies (Nishida et al., 1985; Ghonem and Kalousek, 1988; Inoue et al., 1991), which show that
cracks initiate by fatigue failure. The number of loading cycles before fatigue failure depends on the
contact stresses, and the contact stresses are functions of the contact geometry and interacting forces,
such as traction at the wheel/rail interface. Preventive grinding removes “micro” cracks (10 microns long,
or less). Generally, these cannot be inspected by ultrasonic (or other) detectors, let alone visually. The
basic questions of concern for optimizing the efficiency of maintenance are: when and how often to
grind; what amount (i.e., depth) to grind off; and just how grinding should be carried out. Preventive
grinding should maintain the desired rail profile as far as possible, but should not remove more metal
than is required to free the rail of fatigue cracks.