After experiencing ongoing problems with the bearings on a vital milling machine at a steel plant, the management team turned to NSK for a solution. This decision proved to be extremely lucrative, with the steelmaker now enjoying annual savings of €35,600.

The steel facility produces rails for lift equipment that require the machining of two flat areas at the ends, which assist the fitting of the rails during assembly. While the time required to mill these rough surfaces is short, the stiffness of the machine’s spindle is critical due to the length of the rails. However, using the milling machine’s original bearings, the steel plant noticed that spindle stiffness reduced after just three months, making it necessary to change the spindle assembly, including motors.
Faced with a recurring and expensive situation, NSK was asked to find a solution. Expert NSK engineers visited the plant and analysed the spindle design as part of its AIP Added Value Programme. Following their analysis, it was recommended that the spindle be redesigned with a four row bearing set, instead of three, thus increasing the radial load capacity and radial stiffness. The contact angle was also changed from 15° to 25°, to increase the bending stiffness of the shaft.
NSK’s high precision angular contact ball bearings (ACBB) were selected from its range of standard products.
After the steel plant had implemented the change, the bearings continued working in the milling machine for more than 12 months, with no failures experienced in the motor or transmission. Today, the steelmaker no longer has to endure four production stops a year, while the costs for the replacement spindle assemblies and motors have also been eliminated. Taking these factors into account, it has been calculated that the plant is
saving €35,600 per annum.
For further information www.nskeurope.com