A tire production plant has seen cost savings of €119,000 (US$133,000) per year thanks to NSK’s molded-oil bearings. Having replaced the conventional bearing units in a rubber cutting machine with the NSK molded-oil bearings, which are permanently lubricated with an oil-impregnated polymer material, the facility is witnessing a fourfold extension in bearing service life.
Water spray generated by the tire cutting process is known to shorten the service life of standard ball-bearings deployed in such applications. However, at this particular plant the problem was exacerbated by inadequate protection at the bearing locations. As a result, the maintenance team was faced with replacing the bearings prematurely, typically twice a year. This was in addition to an average of two unscheduled stoppages per annum due to catastrophic bearing failures and line stops.
Within the framework of its proven AIP added-value program, engineers from NSK visited the plant to see the application first-hand before analyzing the bearings at one of its technology centers. It was confirmed that the principal cause of bearing failure was the ingress of water from the rubber cutting process. NSK determined that the best solution would be the adoption of stainless steel-mounted units with molded-oil inserts.
In ball bearings featuring this technology, the penetration of water and other contaminants is prevented by a resin containing a supply of lubricant that is distributed in small, continuous quantities onto the raceway. In comparison with resins used by manufacturers of competitor bearings, the ratio of lubricant present in NSK’s molded-oil bearings is significantly higher (often over 50% more), thus extending service life.
The mounted molded-oil units now being deployed at the tire manufacturing plant feature a housing made from a one-piece austenitic stainless steel casting. The bearing rings, balls and raceways are also made of stainless steel, while further corrosion resistance for both the housing and bearing interior is assured by the molded-oil resin coating.
May 26, 2016