SKF and the W.S. Tyler processing arm of Haver & Boecker have partnered together using SKF upgraded Explorer bearings to engineer a solution 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 significantly 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 sector. 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 performance, reliability and efficiency.
In many instances, the key to achieving these goals lies not just in the performance 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 failure 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 unexpected component failures can lead to costly maintenance situations, with unplanned downtime and loss of valuable productivity.
The Problem
An operation in Arizona was experiencing a series of costly bearing failures on the vibrating screens operating at its crusher plant. The failures were occurring 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 scheduling a replacement or rebuild of each bearing assembly in the screen every 7,500 hours as part of a time-based preventative maintenance plan.
The Opportunity
During 2011, as SKF was preparing to launch its upgraded SKF Explorer bearing, it offered Haver & Boecker – 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 microstructure while maintaining a high level of ductility. The result is increased service life reduced internal wear, a high level of fracture resistance in poorly lubricated and highly contaminated application conditions.
The bearings supplied to Haver & Boecker were upgraded SKF Explorer 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 safety. SKF offers a full range of SKF Explorer spherical roller bearings for vibrating screens (VA405 and VA406 suffix), all with the hardened 2-piece outer ring guided cages, C4 radial internal clearance, and reduced bore and outside diameter tolerances.
The SKF Explorer VA406 spherical roller bearings with PTFE-coated bore that provides additional benefits in vibrating screen applications because the PTFE coating eliminates fretting corrosion between the shaft and the bearings. All standard spherical roller bearings, 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 maintenance 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 upgraded SKF Explorer bearings, at the mine’s crusher plant in 2011. “The mine is very pleased with the support our partnership with SKF gave them in helping to solve this critical bearing and lubrication issue,” Fuller said.
“The F-Class vibrating screen featuring the upgraded SKF Explorer bearings are tested and proven to offer nearly double the service life in poor lubrication conditions and twice the service life in contaminated conditions,” said Keith Meyers, global industry manager, mining mineral processing and cement, SKF. “The operation of the F-Class with upgraded SKF Explorer bearings at the Arizona copper mine match these results.”