6.1 Rail grinding issues
Conventional rail grinding is undertaken with motors that rotate about an axis normal to the rail, typically at 50Hz. For a typical grinding speed of 5-8km/h, this gives a periodic grinding signature at 25-40mm wavelength. Severe grinding, large stone grits and grinding “chatter” can give a pronounced signature, such as that shown. Traffic may cause a characteristic “whistle” until scratches wear away.
Coincidence of the grinding signature with corrugation wavelengths should be avoided as corrugation otherwise returns quickly.
Extreme cases of deep residual grinding scratches, hard rail and low contact stress can initiate surface spalling. This is undesirable and avoidable.
Other grinding techniques can give lower longitudinal roughness but are less able to modify the rail’s transverse profile.