How Do Ball Bearings Reduce Friction of Moving Parts?

Blog | January 29th, 2019

Ball bearings are what most folks think about when they imagine rolling elements. Sure, a proprietary roller type will handle a predetermined frictional load, but these elements aren’t exactly versatile. They’re built to satisfy specialized rotating applications. As for ball bearings, they can rotate in any direction, as directed by multiple loading forces.

Ball Bearings Are Vectorless Assets

Rolling radially, several contact points on each ball run along the twin races. The motion is predictable, the loading effect determined, and the circumferential spin maintained until the radial energy is removed. If other directional vectors are supplemented, then the balls easily adjust in response to the secondary forces. Again, specialized rolling-element types find it hard to adapt like this because they’re designed to roll in a single direction. Multi-directional assets by design, ball bearings are built to slide past one another while they rotate around a fixed axis, and they also absorb significant quantities of thrust energy. An oily film makes the sliding action possible, of course.

Fundamental Omnidirectional Rolling Aptitude

There are other sliding part forms in engineering science. They slip past each other, again as permitted by a lubricating film. For ball bearings, the sliding principle is in play, with oil again helping the frictionless motion, but now the curved spheroids introduce a rolling motion to the device configuration. Also, because there are instantaneous points of contact, there’s a stationary component ingrained in the component mix. Picture the interior of the bearing. There are few contact points, polished metal or ceramic surfaces on each ball, and they’re racing down the interior surfaces of the bearing rings. Strange, on viewing the matter from a theoretical perspective, maybe ball bearings shouldn’t even need a lubricant, but that’s a ludicrous thought, right?

Ball Bearing Limitations 

Indeed it is, because the spheroids are made of real-world materials, and materials always come with manufacturing imperfections. Polished or not, the points at which the balls touch one another and the two rings will result in friction. Therefore, although this bearing type can handle different loading forces, it is best used as a general purpose solution. Otherwise, placed under a heavy load, the tiny contact zones will generate so much heat, they’ll weld to one another. Improving their handling capabilities, advanced lubricants make these all-around friction mitigators tough and versatile.

What’s a ball bearings finest feature? That’s simple, ball bearings can roll in any direction. But wait, that same benefit can become a drawback. Because spherical bearings can only make contact at a handful of reduced area points, they generate heat at those small-surface zones. As that heat increases, perhaps because of a heavier load or a ball surface imperfection, the balls produce micro-welds and fail.

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