The savings are the result of NSK providing a solution to a long running problem of premature bearing failure on the pulp converting machine. The guide rollers on the machine are driven by a cellulose web, so low torque operation is a decisive factor in optimising their operation. Initially, to cater for this requirement, bearings with split seals were used. However, these units had to be changed every 6- months due to ingress of contamination in the form of paper dust.
An analysis of the machine operation revealed that the recurring failure of the split seal bearings was costing the converter company €12.000 annually: this figure including production losses, maintenance costs and bearing replacement every 6 months.
Solving the problem by retrofitting the bearings with standard bearing seals that provided higher levels of ingress protection was not an option, due to the high levels of friction that would result. Other options considered were also discounted because the required balance between improved sealing efficiency and reduced friction could not be achieved.
With the problem still unresolved, the pulp converter learned about NSK’s asset improvement programme - a value-added service that helps bearing users to solve bearing problems, reduce operating costs, improve efficiency and profitability. As part of the AIP programme, NSK engineers visit customers’ premises, analyse problems, and work out what NSK can do to provide support.
NSK engineers visited the pulp converter and reviewed the operation of the problem machine. They concluded that the best solution to prevent ingress of paper dust, and subsequent premature bearing failure, was to change the existing bearings for NSK’s Molded-Oil units. These bearings are practically frictionless and also provide excellent protection against dust penetration. In addition, the solid nature of the Molded-Oil lubricant minimises the risk of oil leaks and, therefore, avoids contamination of the pulp and the machine itself.
Following a successful test phase, the Molded Oil bearings were installed in three converting machines. The success of this bearing substitution is evident from the performance of the bearings which are still operating 18-months after installation. What this means for the user is that, for an outlay of just €1,440, he has saved €10,560 (the €12,000 annual cost of bearing failure minus the cost of the bearings).