Long-life Conveyor Bearings reduce Cost

Quarrying and Mining compabies can significantly reduce maintenance costs by selected the right bearings. (Picture: NSK)

NSK's Asset Improvement Programme (AIP) for cost reduction has achieved a major success with a large quarrying and mining company, delivering achieving annual cost savings of EUR 14 389 per year.

The significant cost savings resulted from solving an ongoing bearing reliability problem on an overhead quarrying conveyor, replacing the existing bearing inserts with NSK's Molded Oil bearings.

The problem with the conveyor was regular failure of bearing inserts, every 2-months, or approximately 440 hours of operating time. These failures were due to the harsh environment where the inserts were exposed to ingress from water and abrasive particles. In addition, the bearings were assembled 5 metres above the ground, making inspection and maintenance tasks especially difficult, and also the possibilities for predicting premature failure.

The annual cost for replacing the bearings themselves was not too onerous, at EUR 540. However, this figure was dwarfed by the annual cost for the downtime resulting from the bearing failures, EUR 15 750. What all this added up to for the quarry was an annual cost of EUR 16 290 for bearing failures and the downtime and lost production resulting from them.

Clearly this cost was unsustainable, so an initiative was launched with a view to sourcing higher performance bearings. As part of this initiative, engineers from NSK's AIP cost reduction programme were called in to give advice. The cost reduction programme is a value-added service that actually helps bearing users to improve reliability, reduce operating costs, and improve efficiency and profitability. These objectives are achieved by delivering tangible savings to assets, such as equipment and machinery, and also by improving the working knowledge of maintenance and engineering personnel.

NSK engineers visited the quarry, inspected the overhead conveyor and identified the problem. They suggested a solution using NSK's Molded Oil Bearings, which they were certain would prolong bearing life.

Molded Oil bearings employ a special solid lubricant to positively transform the performance of machinery in environments exposed to high humidity, corrosion and contamination. The bearings achieve improvements in performance and reliability by offering more than twice the operating life of grease lubrication in water- contaminated environments. The solid lubricant technology also means that there is no need for refilling of lubricant, as Molded Oil provides a continuous supply of lubricating oil.

Molded-Oil bearing inserts were fitted to the conveyor and have subsequently provided dramatically extended bearing life. According to NSK, the bearings have already exceeded the life of the previous bearing inserts by a factor of 9, delivering 19-months of trouble free operation (4140 h). The resultant savings from this improved operation are considerable. n