Coal Age

AUG 2016

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34 www.coalage.com August 2016 dragline maintenance New Options for Dragline Maintenance Optimize Production Performance by ryan sharp and charles constancon Mining companies around the world are continuing to feel the effects of low prices and the added pressure of weak demand. This has resulted in many com- panies putting even greater pressure on their plant and equipment assets in an effort to increase revenue through in- creased production. The engineers at BMT WBM, a sub- sidiary of BMT Group, believe a sustained increase in production can only be truly realized when robust maintenance pro- cedures are in place. Taking a closer look at draglines, they considered the current maintenance challenges and highlight how technological innovations can help optimize and, in some cases, reduce maintenance and inspection workloads. Over the past few years, the mining industry has had to deal with difficult times. As a result of external market forces beyond their control, mining companies in many cases are no longer able to justify the capital expenditure for the purchase of new larger machines and much of the focus has been on devising upgrades to existing machinery to help improve pro- duction capacity through increasing pay- loads and reducing cycle times. However, increasing payloads and re- ducing cycle times often have the effect of reducing the service life of machinery components and structures due to in- creased duty. With resistance to "avoid- able" downtime, too often payloads are increased and cycle times reduced with- out the required machine upgrades be- ing installed, based on the expectation that the increased maintenance cost and effort required would be more than jus- tified in consideration of the increase in production. The approach toward maintenance has often been ad-hoc and "convention- al" with maintenance plans for a piece of equipment often simply put togeth- er on the basis of recommendations or instructions obtained from the original equipment manufacturers (OEMs) for the operation in the original machine config- uration. As a consequence, certain pre- ventive maintenance tasks have become standardized, remaining somewhat un- changed and unreflective of the change of duties or increased loads handled by the upgraded plant and machinery. Time for a Change With strong emphasis on mining machin- ery availability and the continuing trend toward operating at increased rates of production, this "conventional" approach is no longer sustainable and mining com- panies must now look at using every avail- able tool and technique to improve main- tenance practices. Although the OEMs will provide maintenance departments with guidelines for servicing plans based on the specification on which it left the factory, what many operating companies do not consider is the effect that increas- ing the machine's capacity or duty cycle will have on reliability and the required maintenance. Often, machines will be upgraded to operate significantly above their original design loading. Such upgrades create specific issues that cannot necessarily be dealt with in the traditional way, i.e., when something breaks, it is simply replaced or when it cracks, it is welded. This approach simply does not work when a machine has been pushed beyond the original de- sign specifications as it leads to an unac- ceptable "mean time between failures" (MTBF). When increasing the load, it's important that the implications of this change are duly considered and thought is put into how one ensures the original design reliability is maintained to avoid further issues in the future. Otherwise failure rates will increase and availability Engineered dragline supports used during major overhaul help to reduce future structural problems. Engineered dragline supports used during major overhaul help to reduce future structural problems. Technological innovations can help optimize and in some cases reduce maintenance and inspection workloads

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