MINE MAINTENANCE
Extending winder rope service life
Mine winder ropes operate under severe bending fatigue, where crack initiation and growth concentrate at the outer-strand crown due to high local contact stress and micro-slip during sheave passage.
Although ropes are factory-dressed with bitumen coatings to provide early corrosion protection, this coating hardens in service, fractures away from the crown profile and no longer maintains a stable tribological film at the fatigue-critical interface. To actively manage crown-wire fatigue, lubrication must therefore be re-established in service, with precision, pressure delivery and repeatability, Lubrication Engineers South Africa says.
A major South African deep-level mine evaluated a structured lubrication program built around the Viper Wire Rope Lubricator( Viper WRL), using Wirelife Almasol Coating Grease( LE 452) as the coating medium. The Viper WRL system was selected for its ability to pressure-inject coating grease into the crown / valley interface, deliver a controlled mass per 100 m and achieve uniform film formation over the working length of rope in each lubrication cycle – conditions essential to influencing fatigue behaviour during high-cycle operation.
Historical inspection data across multiple years provided a clear baseline of crown-wire fatigue progression. Prior to the Viper WRL application, the rope exhibited an accelerating rate of crown-wire break development, consistent with the mechanics of friction-dominated bending fatigue. Following introduction of the Viper WRL and Wirelife Almasol Coating Grease( LE 452) lubrication system, this trend changed materially: over the subsequent inspection period, no new crown-wire breaks were recorded, despite the rope having already entered the acceleration phase of fatigue, Lubrication Engineers South Africa
The Viper Rope Lubricator system was selected by the deeplevel gold mine in South Africa for its ability to pressure-inject coating grease into the crown / valley interface, deliver a controlled mass per 100 m and achieve uniform film formation over the working length of rope in each lubrication cycle, Lubrication Engineers South Africa says
says. The change in trend was quantified using standard reliability modelling for fatigue events, confirming an approximately 85 % reduction in the underlying crown-wire break hazard rate following adoption of the Viper WRL system.
“ The outcome is attributed to the system effect: Wirelife Almasol Coating Grease( LE 452) produces a durable, low-shear boundary film through the Almasol wear-reducing additive, while the Viper Wire Rope Lubricator ensures that film is delivered under pressure directly into the fatigue-critical interface, in consistent mass and at a disciplined interval,” the company said.
Based on the validated model, had the Viper WRL lubrication program commenced within four weeks of rope installation, the same rope would be expected to reach the standard fatiguebased discard reference four to six years later than under factory bitumen dressing alone, it claims.