MAINTENANCE
The bearing is of the upgraded SKF Explorer class with improved wear resistance, thanks to the patented material heat treatment process that nearly doubles service life in poor lubrication and contaminated conditions.
SKF says it was chosen to supply the bearing due to its Application Engineering expertise and support, and the knowledge and experience in manufacturing large size industrial bearings.
Daniel Ortega, Project Manager at the Gothenburg factory, says:“ We have worked in close cooperation with the customer, in order to design an optimum 241 / 1,250 bearing that is particularly suitable for applications in the mining industry. These applications have extreme operating conditions and are very demanding from a bearing service life perspective.”
NSK has developed new spherical roller bearings for conveyor belt drive pulleys used in harsh environment applications that offer simple installation and excellent sealing efficiency. Although ideal for new-build conveyors, the use of standard, ISO-compatible dimensions means they can also be retrofitted to existing conveyor systems.
The service life of roller bearings used in conveyor belt drive pulleys is an important factor in governing system availability and reliability, particularly in the mining and quarrying industry where conveyors can be several kilometres in length. The selected bearings must not only be able to withstand high loads, but resist penetration by fine grains of particulate present in the working atmosphere.
Spherical roller bearings are typically selected for such applications because they can accommodate high loads and compensate for drive shaft deflection. Until now there were two types of design from which to select. One choice was the use of open bearings with no seals, which could be installed easily and without risk of error because the bearing clearance was easy to set. However, early failure was to be expected with this type of bearing due to the penetration of foreign particles, some of which are highly abrasive.
The alternative has been to use sealed spherical roller bearings, but these have the disadvantage that bearing play cannot be measured when being fitted, which increases the risk of installation errors. What’ s more, the seals require additional space to ensure their load rating potential is maximised.
With these factors in mind, NSK has developed new spherical roller bearings specifically for conveyor belt drive pulley applications in sectors such as mining and quarrying. They offer long service life, high load ratings, excellent sealing and dimensions identical to the bearings that were previously in use. In addition, bearing clearance can be measured at any time during installation.
Among the bearing’ s principal features, NSK has developed special steels for the inner and outer rings, which in combination with a specific annealing process, increase load capacity and make for a very compact design. As a result, the seal can fit within the available space and ensure the new spherical roller bearings are still able to attain higher dynamic load ratings than conventional bearings.
“ The special steel materials perform exceptionally well, even when poorly lubricated, while the very efficient seal has proven its resistance in many other harsh environment applications. Importantly, the seal is attached by a bracket screwed to the bearing housing so that it can be removed during installation to measure the bearing radial clearance. This ensures that the clearance is not set too small when sitting tightly in the inner ring, thus preventing early damage to the bearing. NSK estimates that its new spherical roller bearings offer quadruple the service life of conventional alternatives.”
Automated lubrication systems
Proper lubrication is also integral to ensuring the functionality of components and systems within heavy-duty machinery.“ If there’ s a bushing, bearing or gear, something that is rotating or sliding in
Comminuting
your maintenance expenditure
Köppern roller presses have been proven successful all over the world in plants for the energy-saving high pressure comminution of various ores and minerals like iron ore, copper, gold, molybdenum and diamonds, as well as cement clinker, limestone and blast furnace slag. For the comminution of abrasive materials a Köppernpatented wear protection of rollers is available. Köppern – Quality made in Germany.
• State of the art technology
• Process technology know-how
• High plant availability
• Quick roller replacement
Pilot HPGR testing capabilities in Australia, Canada, Germany and South Africa
For further information please contact sales @ koeppern. de www. koeppern. de
JANUARY 2017 | International Mining 39