Using the Rope Damage Index to Predict the Endurance of Mine-Shaft Wire Ropes in Canada
Technical Meeting The Non-destructive Testing of Rope – Krakow 1995
Mining companies are constantly searching for new ways to increase the return on their capital investments. ln underground mining, one opportunity for improvement is to maximize the use of the mine shaft by either increasing the maximum depth or the capacity of the hoist, while keeping the operation safe and reliable. As a consequence of the high workload of today's mine hoists, the service life of the wire ropes can be significantly reduced. lt appears that to maintain both safety and cost-effectiveness at satisfactory levels, it becomes increasingly important to be capable of accurately predicting the safe service life of mine-shaft wire ropes. While in theory it should be possible to predict the endurance of a wire rope based only on the dynamic loading history of the hoist, in practice it is much safer, and mandated by regulation in most countries, to submit the rope to periodic Non-Destructive Testing. This paper presents a method to determine the remaining safe service life of a wire rope based on NDT results. The "Wire Rope Damage Index" (or Rope Damage Index, RDI) was developed with the objective of simplifying the interpretation of NDT results, thus improving the predictive potential of the technique. The RDI is computed from the established LMA (Loss-of-Metallic Area) and LF (Local Fault) signals, and represents, as closely as the measurement allows, the cumulative degradation of the wire rope. Once calibrated for the specific installation, the Rope Damage Index will be used by the mine operators to determine the optimal safe service life of the rope, and the hoist will be monitored at short time intervals until the retirement criteria are reached. Test results from laboratory experiments as well as from an actual mine shaft operation are presented to illustrate the use of this concept.
Author(s): M. Hamelin, L. Hofmeister & K. Leung