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82 • ROCK products • May 2015 www.rockproducts.com EQUIPMENT & TECHNOLOGY SCREENING & SIZING S KF and the W.S. Tyler processing arm of Haver & Boecker have part- nered together using SKF upgraded Explorer bearings to engineer a solu- tion that has doubled the service life of their F-Class screens. After using the upgraded SKF Explorer for more than 15,000 hours without problems, one of Haver & Boecker's mining customers was able to signifi- cantly boost efficiency by extending its time-based preventative maintenance program to just once every three years. Background Maintenance represents a significant proportion of the overall operating costs in the mining and quarrying sec- tor. As a result, mining and quarrying organizations are now increasingly looking to contain and reduce costs on machinery such as vibrating screens in order to sustain profitability, primarily through improvements in machine per- formance, reliability and efficiency. In many instances, the key to achiev- ing these goals lies not just in the per- formance of large machinery, but also in the smaller components, including bearings and seals. If these essential but frequently overlooked components fail to function, then overall system fail- ure and downtime is inevitable. Heavy loads and harsh environmental factors place extreme demands on vibrating screens and their moving components. As a result , frequent and/or unex- pected component failures can lead to costly maintenance situations, with unplanned downtime and loss of valu- able productivity. The Problem An operation in Arizona was experienc- ing a series of costly bearing failures on the vibrating screens operating at its crusher plant. The failures were occur- ring every 5,000 to 6,000 hours due to a lack of lubrication, contamination or ineffective lubrication and had become so routine that the mine was schedul- ing a replacement or rebuild of each bearing assembly in the screen every 7,500 hours as part of a time-based pre- ventative maintenance plan. The Opportunity During 2011, as SKF was preparing to launch its upgraded SKF Explor- er bearing, it offered Haver & Boeck- er – a long-time user of SKF Explorer bearings for vibratory applications – some prototypes for testing. Haver & Boecker chose to install the prototype upgraded SKF Explorer bearings in an F-Class screen. Upgraded SKF Explorer bearing steel is manufactured with a patented heat treatment to increase the material hardness and provide a refined micro- structure while maintaining a high lev- el of ductility. The result is increased service life reduced internal wear, a high level of fracture resistance in poorly lubricated and highly contami- nated application conditions. The bearings supplied to Haver & Boecker were upgraded SKF Explor- er bearings for vibrating applications. SKF Explorer spherical roller bearings bring the benefits of the enhanced bearings to vibrating screens, resulting in lower maintenance and repair costs, reduced downtime, and improved safe- ty. SKF offers a full range of SKF Explor- er spherical roller bearings for vibrat- ing screens (VA405 and VA406 suffix), all with the hardened 2-piece outer ring guided cages, C4 radial internal clear- ance, and reduced bore and outside diameter tolerances. The SKF Explorer VA406 spherical roll- er bearings with PTFE-coated bore that provides additional benefits in vibrat- ing screen applications because the PTFE coating eliminates fretting cor- rosion between the shaft and the bear- ings. All standard spherical roller bear- ings, spherical roller thrust bearings and CARB bearings now benefit from the upgraded manufacturing process in bearing steel that increase bearing life and reliability, especially under poor application conditions. The Solution After using upgraded SKF Explorer for more than 15,000 hours – double the length of the existing time-based main- tenance schedule – the mine was able to modify and extend its time-based preventative maintenance plan to a period of three years. This has resulted in maintenance parts cost avoidance savings of $23,660 per machine, plus no production loss at a cost of over $15,000/hour. Lyndell Fuller, general manager, Haver & Tyler Grand Canyon, Inc., oversaw the installation of the F-Class screen, equipped with the prototype upgrad- ed SKF Explorer bearings, at the mine's crusher plant in 2011. "The mine is very pleased with the support our part- SKF Bearings Double Service Life Of Vibrating Screens Continued on page 84