With a higher performance than traditional steel bearings, hybrid bearings are a combination of steel or stainless steel rings, used in conjunction with silicon nitride ceramic balls. Although rolling elements (ceramic balls) can on some occasions take up to 60 days to manufacture, they can be up to 58% lighter, four times smoother and have a 70% reduced thermal expansion which can typically run at operating temperatures between 14-47°C lower than standard steel bearings. A combination of those pioneering properties can heighten efficiency, ensure that the bearings are less prone to the effects of contamination and corrosion, and have a greater intolerance to heat.
There is an opportunity for bearings to be tailored for a specific industrial application, with a combination of different ball bearings, rings, seals, cages and greases. With advancements in new material technology that make use of ceramics and coatings, the opportunities for continuous optimisation are extended. Coating options could include a hard coat, corrocoat (chromium) or black oxide. Cages can be formed of either steel, polyamide PA66, brass or PEEK, for example.
Lubrication is a vital part of every bearing’s optimal function, and this can also be considered to suit the application. Units can be offered with mineral or synthetic greases, or a solid lube polymer matrix saturated with lubrication oil, which can help to prevent contamination ingress and add protection in washdown environments. A specific grease could also prove useful in 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 significant factor, the additional expense of hybrid bearings in particular is certainly not relevant to each and every bearing application. Many maintenance engineers will have experienced at least one application where repeated and frequent bearing failures have led to regular loss of production, increased maintenance costs, as well as probable 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? With new technological advancements, there could be a solution to aid the reduction of bearing failure downtime – whether it’s an off the shelf product, or a bearing designed to suit your very specific, individual needs.
APPLICATION
For instance, at Bearings and Drives alongside CeramicSpeed, bespoke bearings can be sourced and hand built in 7-10 days. For example, we worked with a local dairy, where due to frequent wash downs of the machinery with aggressive caustic cleaning agents, regular cam bearings were failing about every two to three weeks, so it was imperative to find a solution.
As an integral part of the production line, with the bearings located at the heart of the machine, the failure resulted in the line being out of action for eight hours while it was stripped down to replace the failed bearings. By replacing the existing bearings with a CeramicSpeed corrocoated unit, with an FDA-approved grease and ceramic balls, and by manufacturing 316 stainless stub shafts, the bearing life was increased to five months.
Despite the initial increased cost for the bearing and manufactured shafts, an ROI calculator indicated that savings over a 12-month period equated to in excess of a significant £250,000 per year, when all costs including loss of production are considered (based on eight bearings).
As new technologies emerge, not only can the lifespan of bearings be increased by an approximate factor of nine times, but the potential to increase production and make significant cost savings in reduced down time is unlocked.