Koyo’s new anti-creep ball bearings
What exactly is bearing creep?
Bearing creep is a phenomenon whereby the inner or outer ring rotates in relation to the housing or axis during operation. A pinch point forms and as the balls pass over it on each rotation it moves. It’s undesirable because it causes accelerated wear, discolouration and scuffing. If that wasn’t bad enough, if a bearing tilts on its centre line axis it can lead to problems like excessive noise, poor gear engagement or even catastrophic failure of a whole system.
There are two types of creep: strain and corotation. In the first type, a large unidirectional radial load causes circumferential strain on the outer ring, resulting in a small, slow moving area of strain. In the second type, which can occur when loads are light, rotational torque causes the outer ring to move due to insufficient friction between it and the housing. This is also potentially very destructive and the creep speed can be much higher.
How is bearing creep prevented ?
Various measures have been tried in the past, such as using a thicker outer ring or a more solid lubrication film, however there are size, weight and cost implications here. Simply altering the housing dimensions to tighten the fit causes more problems than it solves as this excessively preloads the bearing’s internals causing heat, friction and wear. Also this approach often doesn’t work where an aluminum housing is used due to the material’s thermal properties. So in 2016 JTEKT decided to approach the problem from a new angle, developing the New Structure Anti-Creep Ball Bearing.
The design features a circumferential groove in the centre of the outer ring’s outside diameter to tackle the strain creep. To be sure of the perfect contour, the company conducted extensive CAE analysis using a simulation model based on the actual test device which was used to check the results. Results were confirmed by a video analysis. KOYO 6302/C3 bearings online , pls click here :
This clever combination means the bearing can perform like an equivalent with a thicker outer ring, but without the size and weight penalty. This is particularly important for industries like automotive, but also increasingly important in various other industries like machine tool manufacturing where creep-related wear can be problematic. JTEKT has also noticed increasingly strict requirements in other industries too, such as agricultural and construction equipment. By saving on material, the design also keeps costs down.
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