Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr
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REBUILDS 24 E&MJ; • JANUARY 2017 www.e-mj.com Aging equipment carries a cost to any operation, as maintenance bills creep up steadily and machine availability declines. The question for any maintenance manager is, when to decide that enough is enough, and begin to look at replacement options. In boom times, the obvious response is to buy new, although even that strat- egy may come unstuck if the equipment manufacturer already has a full order book and a long lead time for delivery. When markets are down and the funding needed for a new machine is scarce, then spending less to obtain a rebuilt unit be- comes increasingly attractive. Of course, there is also the bazaar scenario, in that the manufacturer may be more amenable to haggle over the price of a new truck, loader, scraper or whatever in order to keep the production line running. And, conversely, the unavailability of new ma- chines in short order when that line is working to capacity may lead the operator to investigate rebuilding just to get fleet capacity back up to where it is needed. Clearly, there are plenty of permuta- tions that in certain circumstances can favor one approach over the other, or vice versa. Geography can also play a role here, in that getting access to a remote loca- tion either to bring in new equipment or to recover old machines for rebuilding at an off-site workshop may be challenging. Then again, the type of equipment involved obviously has an impact on the decision-making process. Rebuilding a pickup, aside from replacing bent body panels, is unlikely to be a sensible op- tion. On the other hand, rebuilding a ma- jor, high-cost plant item such as a shovel or a dragline that already has plenty of hours on the clock, but has the potential to go on indefinitely after some fairly ma- jor transplant surgery can look like a very attractive proposition to those in the cor- porate finance department. Safety is another, and often complete- ly separate consideration. In the 1970s, there was a situation in the U.K. when there was effectively a complete recall of one particular manufacturer's 50-ton haul trucks, which were then widely used in both surface mining and quarrying. A catastrophic failure in both main frames caused a fatality, after which all of the trucks of this type were systematically withdrawn for inspection. Where frame cracking was found, not only was rein- forcement plating installed but—in the case of the mine where the author was working was concerned—the opportunity was taken to strip each machine down to basics and then rebuild to as-new specifi- cations. In this instance, the trucks were being used by a cost-conscious mining contractor, and had already run up long service, so the enforced layoff provided the rationale for returning them to further work without having to invest in replacements. Joy Global: Rebuilds Across the Range Joy Global told E&MJ; that for both partial and full rebuilds it undertakes, the pro- cess begins with a pre-rebuild condition audit that includes a review of mainte- nance records, assessment of structures, and evaluation of component health. The company will supply a list of recommend- ed productivity and reliability upgrades as well as mandatory upgrades (where required) with every rebuild, after which customers receive updated documenta- tion for their machine. For surface and underground equip- ment, partial rebuilds are extended in- terventions focused on replacing com- ponents and performing repairs aimed at ensuring machine performance and minimizing downtime between partial and major rebuilds. Surface equipment major rebuilds, carried out at or around the machine's midlife span, entail major overhauls of shovels, drills, loaders or draglines, and involve auditing, disassem- bling, reconditioning, updating, reassem- bling, testing and performance evaluation. For example, a major overhaul for shovels is defined as a complete rework, including undecking the machine to replace the roll- New Life for Old Replacing time-expired mining equipment like-for-like with a new machine is sometimes not an option, especially when capital budgets are tight. Carefully undertaken, rebuilds can offer a viable alternative, producing as-new plants for lower investment. By Simon Walker, European Editor Joy Global's rebuild process begins with a pre-rebuild coniditon audit, with the company supplyng a list of recommended productivity and reliability upgrades.