If you design or maintain rotating machinery, you already know the question is never just “which bearing fits the bore.” It’s whether that bearing will survive the load, speed, and environment you’re putting it in. This guide walks through the major ball bearing types, how to read a load rating correctly, and a practical framework for narrowing down a selection—and if you’re also weighing bearing material against your environment, see our companion post on ball bearing materials, benefits, and shortfalls.
How a Ball Bearing Works
A ball bearing lets two parts rotate relative to each other while minimizing friction and carrying load. Four components do the work:
Mounted to the rotating shaft.
Mounted to the stationary housing.
Rolling elements that carry load between the rings.
Spaces the balls evenly and prevents ball-to-ball contact.
Because balls make point contact rather than the line contact used in roller bearings, ball bearings generally carry lower loads than an equivalently sized roller bearing but run faster, quieter, and with lower friction. That trade-off is the starting point for almost every bearing decision on this page.
Types of Ball Bearings
Deep Groove Ball Bearings
The workhorse of the bearing world. The raceway groove is deep enough to carry substantial radial load plus moderate axial load in either direction, and the design tolerates minor misalignment. If you’re unsure where to start, this is usually it. Browse deep groove ball bearings in the MISUMI catalog.
Angular Contact Ball Bearings
The contact line between ball and raceway sits at an angle (commonly 15°, 25°, or 40°) to the bearing axis, allowing much higher axial load capacity than a deep groove design—but only in one direction per bearing. They’re frequently mounted in matched pairs to carry thrust from both directions and add stiffness, a common setup in spindles, gearboxes, and ball screw supports. See our related post on how ball screws use bearing principles for thrust support in linear motion systems.
Thrust Ball Bearings
Built to carry axial load almost exclusively, with little to no radial capacity. Common under rotating platforms, in swivel joints, and anywhere load pushes along the axis of rotation rather than sideways against it. View thrust ball bearings on MISUMI.
Self-Aligning Ball Bearings
A spherical outer-ring raceway lets the bearing accommodate significant shaft misalignment or housing deflection without binding. Load capacity runs lower than a comparable deep groove bearing, but they earn their place on long shafts, agricultural equipment, and structures prone to flexing.
Miniature and Instrument Ball Bearings
Scaled-down deep groove or angular contact designs, sometimes just a few millimeters in bore diameter. Used in precision instruments, small motors, medical devices, and robotics where space is tight and precision matters more than raw load capacity.
Thin Section (Slim) Ball Bearings
A large bore relative to a thin cross-section, common in robotic joints, semiconductor equipment, and rotary tables where weight and envelope size are at a premium. For linear counterparts to this space-saving logic, see linear ball bearings (ball bushings).
Understanding Load Ratings
This is where a lot of selection mistakes happen, because a load rating isn’t a maximum load before breakage; it’s a statistical fatigue rating. There are two of them, and a life formula that ties them to your actual application.
Basic Dynamic Load Rating (C)
The constant load a bearing can theoretically endure for one million revolutions with a 90% survival rate. Use this rating for any bearing that rotates under load. A higher C rating means more expected life at a given load, or the ability to carry more load for the same expected life.
L10 = basic rating life (90% of a batch of bearings exceed this life) · C = basic dynamic load rating · P = equivalent dynamic bearing load, accounting for both radial and axial load components.
Because the exponent is 3, doubling the applied load cuts calculated life to roughly one-eighth. Small increases in load carry an outsized penalty in expected service life, which is why modest upsizing is often cheap insurance. See the full derivation in MechMinutes: Intro to Linear Motion and the fatigue mechanics behind it in How to Select the Right Bearing, Part 3.
Basic Static Load Rating (C0)
Applies to bearings that are stationary or moving very slowly under load, like a bearing holding a fixture in place or a shaft that indexes and dwells. It corresponds to a permanent deformation of the rolling elements and raceway of about 0.0001 of the ball diameter, the threshold considered acceptable without impairing smooth running. If your application involves shock loads, slow oscillation, or long dwell times under load, check C0 as carefully as C.
Bearing Type Comparison
| Type | Radial Load | Axial Load | Misalignment Tolerance | Typical Use |
|---|---|---|---|---|
| Deep groove | High | Moderate (both directions) | Low–moderate | General purpose |
| Angular contact | Moderate–high | High (one direction) | Low | Spindles, high-speed shafts |
| Thrust | None–low | High | None | Vertical shafts, rotating tables |
| Self-aligning | Moderate | Low | High | Long shafts, misaligned housings |
| Miniature | Low | Low | Low | Instruments, small motors |
Use Cases by Industry
Thin section and miniature bearings support compact joints and rotary tables where envelope and weight are constrained.
Angular contact pairs support spindles and ball screws where axial stiffness and high-speed running accuracy are critical.
Deep groove bearings in pillow block and flange bearing units support conveyor rollers and idler shafts.
Self-aligning bearings tolerate the shaft deflection and misalignment common in long, field-mounted drivelines.
Miniature and instrument bearings deliver smooth, low-noise rotation in compact motors and diagnostic equipment.
Thrust bearings carry the axial load of turntables, index tables, and vertically loaded rotating fixtures.
Key Selection Criteria
How to Choose: Step-by-Step Selection Guide
Frequently Asked Questions
The dynamic load rating (C) is a fatigue-based rating for bearings that rotate under load—the constant load a bearing can theoretically endure for one million revolutions at 90% survival probability. The static load rating (C0) applies to bearings under load while stationary or moving very slowly, corresponding to a permanent deformation of about 0.0001 of the ball diameter. Use C for rotating life calculations, and check C0 whenever a bearing holds load while not turning.
L10 = (C / P)³ × 1,000,000 revolutions, where C is the basic dynamic load rating and P is the equivalent dynamic bearing load accounting for both radial and axial components. Because the exponent is 3, doubling the load cuts calculated life to roughly one-eighth.
Deep groove ball bearings handle combined radial and moderate axial load in both directions and are the standard first choice. For higher axial load relative to radial, use angular contact ball bearings, often mounted in matched pairs. For almost purely axial load, use a thrust ball bearing.
Ball bearing fatigue life follows a cubic relationship with load. Doubling the equivalent dynamic load reduces calculated L10 life to about one-eighth of its original value, which is why undersizing a bearing is penalized so heavily compared with sizing up.
Yes, if meaningful misalignment is unavoidable. The spherical outer raceway lets the bearing articulate without binding, though load capacity runs lower than a comparable deep groove bearing; reserve it for cases where alignment truly can’t be controlled.
The L10 formula assumes clean lubrication, correct mounting, and normal conditions. Contamination, misalignment, poor lubrication, and vibration can shorten actual life well below the calculated value—see Part 6: Bearing Lubrication for mitigation guidance.
- Ball Bearing Materials: Benefits & Shortfalls
- How to Select the Right Bearing, Part 3: Dimensions and Service Life
- How to Select the Right Bearing, Part 4: Limiting Speed, Running Accuracy, and Fits
- How to Select the Right Bearing, Part 5: Preload and Rigidity
- How to Select the Right Bearing, Part 6: Bearing Lubrication
- How to Select the Right Bearing, Part 7: Mounting Design
- MechMinutes Video: Intro to Linear Motion
- Lead Screws vs Ball Screws: Differences, Benefits & Accuracy
- Calculating Loads and Life Expectancy in Roller Rail Systems with Bosch Rexroth
