What are Hybrid Ceramic Bearings?June 26, 2017
The term hybrid ceramic bearing applies to a rolling element class that uses composite technology. A quick look at the metal races reveals refined stainless steel rigidity. That alloy won’t fracture but will absorb large quantities of friction-generated thermal energy. Meanwhile, on looking at the rolling bearings, it’s ceramic, not metal, that maintains a frictionless gap between the races.
Delving into Hybrid Rolling Elements
Fabricated from exotic non-metal materials, such as Silicon Nitride (Si3N4), hybrid ceramic bearings employ two or more polished metal rings. Primarily, the rigid rings are manufactured from heat treated stainless steel. Those spinning foundations act as a frame, a separation space, and an axial connector. Running around the inner circumference of that separation zone, the fracture-resistant steel balls have been replaced, swapped for ceramic rolling elements.
Ceramic Hybrid Bearings: A Logical Substitution
Polished steel spherical elements carry great loads, but they’re far from perfect. Over time, tiny imperfections in the surface finish cause micro-welds to take place. Ceramic rollers don’t suffer from this drawback. Furthermore, their lower mass means ceramic balls are a logical choice for applications that encounter centrifugal extremes. Estimated to be forty percent lighter than a comparably sized steel rolling element, the low-mass products work with superior friction-cancelling properties when high revolution parts reach peak velocity. A fast moving spindle, for instance, won’t “throw” its rolling parts into the race surface because of centrifugal force, so velocity-induced friction is greatly reduced.
Harnessing Composite Properties
Wide stainless steel races absorb and distribute heat. Likewise, a small circular array of ceramic bearings is known to efficiently conduct heat away from the area where that energy is generated. In composite terms, the two materials work in concert to eliminate frictional effects. Additionally, and this next feature is going to sound counterintuitive, steel ball bearings deform as they spin. That dimensional deformation is nearly imperceptible, but it does occur, probably due to the post-process heat treatment work that softened the steel and ingrained the material with fracture-defeating flex. Given that fact, stainless steel parts do deform very slightly. Ceramic bearings don’t change shape. Instead, they retain rigidity but still don’t fracture.
In the past, hybrid ceramic bearings have only been used in a handful of applications because of the expensive nature of the manufacturing process that merges two materials into a single composite product. Today, however, all high-speed spindle bearings have access to the technology. Furthermore, the weld-free rolling elements won’t corrode, not even in the most corrosive setting, so these bearings have become the default friction handlers for the marine industry.
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