40 n BEARINGS AND BELTS March 2024 www.drivesncontrols.com Can ceramic bearings justify their costs? Hybrid bearings, which combine steel or stainless-steel rings with silicon nitride ceramic balls, o er a higher performance than traditional steel bearings. Their ceramic balls can be up to 58% lighter, four times smoother and have 70% less thermal expansivity than those of standard steel bearings. They also typically run at operating temperatures that are 14-47°C lower than steel alternatives. A combination of those properties can improve e ciency, ensure that the bearings are less prone to the e ects of contamination and corrosion, and have a greater tolerance to heat. Ceramic bearings are also non-conductive, making them ideal for use in electric motors, generators and other applications where electrical currents must be avoided. They o er signicant advantages in terms of performance and durability over aluminiumoxide-coated bearings, which are frequently used in these applications. Hybrid bearings can be tailored for specic applications, using a bespoke combination of ball bearings, rings, seals, cages and greases. With advances in material technologies based on ceramics and coatings, the opportunities for optimisation are extended. Coating options include hard coats, Corrocoats or black oxide, while cages can be formed of steel, polyamide, brass or peek, for example. Lubrication is a vital part of every bearing’s functions, and can also be optimised to suit the application. For example, options include mineral or synthetic greases, and solid-lube polymer matrices, saturated with lubrication oil which can help to prevent contamination ingress and add protection in washdown environments. There are specialised greases available for pharmaceutical and chemical applications, where it is critical that no liquid lubrication can be allowed to contaminate a product. While cost can often be a signicant factor, the additional expense of hybrid bearings – which can take up to 60 days to manufacture – is not relevant to every bearing application. Most maintenance engineers will have experienced applications where repeated and frequent bearing failures have led to lost production, increased maintenance costs, and potential damage to other machine components. If bearings are failing on a regular basis, it is important to consider why. Could it be temperature issues, corrosion, contamination, grease problems or a combination of those factors? New technologies can help to reduce bearing failures. One example of the potential attractions of hybrid bearings occurred at a dairy where cam bearings were failing every 2-3 weeks as a result of frequent washdowns of the machinery with aggressive caustic cleaning agents. The bearings were located at the heart of the machine, and the failures resulted in the line being out of action for eight hours while the machine was stripped down to replace the failed bearings. It was imperative for the dairy to nd an alternative. By replacing the bearings with Corrocoated hybrid bearings with an FDAapproved grease and ceramic balls, combined with 316 stainless stub shafts, the bearing life was increased to ve months. Despite the higher initial cost of the bearing and the manufactured shafts, an ROI (return on investment) calculator indicated that the savings were more than £250,000 a year, when all of the costs, including lost production, were considered. This was based on replacing eight bearings. As new technologies emerge, not only can the lifespan of bearings be extended by around nine times, but the potential to increase production and make signicant cost savings in reduced down time is unlocked. n In many applications, hybrid ceramic bearings can out-perform conventional steel ball bearings. Steve Bacon, sales director of Bearings and Drives, looks at the latest technologies that can boost eciency help to deliver advantages to users. Hybrid ceramic ball bearings oer many potential advantages over conventional steel bearings, but these come at a cost premium
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