Open Cut » Maintenance & Equipment
This report details the advances made by CW Pope in their determination to develop a system that enabled the monitoring of crack propogation in large shafts.
Shafts and pins are vital components of large items of coal production equipment including:
- Draglines and Shovels:
- Swing Shafts, Propel Shafts, Boom Foot Pins, Boom Suspension Pins
- Bucket Wheel Reclaimers:
- Longwall Miners:
- Ranging Arm Drives, Conveyor Drives
- Haulage Equipment:
- Sheave Shafts, Winder Drum Shafts
Shafts and pins are susceptible to failures without apparent warning. Consequences of shaft or pin failure are catastrophic with enormous costs in downtime, consequential damage to associated equipment and potential injury to personnel.
Safe operation of plant and equipment relies on pro-active maintenance aided by newly emerging condition-monitoring technologies. Operators of critical plant are particularly interested in early detection of conditions that lead to in-service failures of rotating shafts and fixed pins.
Failures of shafts and pins are usually preceded by fatigue cracking. Current non-destructive examination (NDE) techniques allow in-situ detection of fatigue cracking in shafts and pins. The major shortcoming of these techniques, however, is that crack detection and quantitative analysis of crack length and depth demands a high level of skill and experience. Further, the inherent difficulty of inspection leads to inconsistencies in results and often requires extended periods of access (hence equipment downtime and lost production) for re-evaluation of critical areas.
Coal mining industry maintenance personnel have identified the need to advance in the capabilities of NDE to provide solutions to the current deficiencies in shaft testing. This has been reinforced by recent examples of fatigue cracks that have been monitored in dragline and face shovel swing shafts, dragline walking cam shafts, shovel propel shafts, dragline and shovel boom foot pins. In all of the above components the consequences of failure are very serious.
A system for the ultrasonic examination of shafts and pins has been developed with the assistance of ACARP funding (C7005). The system was designed to satisfy the following key requirements:
- The ability to test and monitor complex shafts
- The ability to detect fatigue cracking at an earlier stage
- The ability to analyse data using advanced techniques to improve characterisation and discriminate
- Provide detailed information to allow correlation of plant history and the development of fatigue cracking
- Capability of implementing automated monitoring of critical or inaccessible components
- The ability to gather repeatable data
- The ability to store historical data
- The ability to trend data
- The ability to collect data with lower skilled people