FRETTING DAMAGE IN LOCKED COIL STEEL ROPES

Locked coil steel ropes are used for high duty applications in aggressive environments, such as those encountered in the mining industry. The service life of this class of rope can be variable. This paper examines the design features of the rope, and the operating regime, which may contribute to this variability in service life. These ropes are constructed from cold drawn eutectoid and hypo-eutectoid steel wires. A rope is examined after a period in service close to its design life. Of the degradation mechanisms considered, fretting is found to produce significant wear at points of contact between the layers of the rope, near its outer surface. Initiation of fretting wear is encouraged by the breakdown of the added lubricant and the magnitude of the contact stresses. Two further papers will examine the fretting behaviour of a typical eutectoid steel wire used in this class of rope. In the first of these papers the residual lubricant coating from the wire manufacturing process is identified as playing an important role in the fretting behaviour. The second paper covers the influence of low viscosity oils, and solid additives, on the fretting behaviour.