“Play” in bearings refers to the internal clearance or looseness between the balls/rollers and the raceways, which allows for smooth rotation and accommodates various operating conditions. There are two types of play: radial play (perpendicular to the bearing axis) and axial play (parallel to the axis).
Here’s a more detailed explanation:
- Radial Play (or Internal Clearance):
- This is the looseness or clearance measured perpendicular to the bearing axis.
- It’s the total radial movement of the outer ring relative to the inner ring.
- It’s determined by the actual raceway diameters and ball/roller diameter.
- It’s designed into the bearing to allow for smooth rotation and to accommodate temperature expansion, misalignment, and thrust loads.
- A small amount of radial play is generally desirable for optimal bearing performance.
- Axial Play (or End Play):
- This is the looseness or clearance measured parallel to the bearing axis.
- It’s the maximum relative axial movement of the inner ring with respect to the outer ring.
- Axial play is also determined by the bearing design and is often interdependent with radial play.
- Importance of Play:
- Smooth Operation: Play allows the bearing to rotate smoothly and reduces friction.
- Load Accommodation: It helps the bearing handle radial, axial, or combined loads.
- Temperature Compensation: It allows for expansion and contraction due to temperature changes.
- Misalignment Tolerance: It can accommodate slight misalignment between the shaft and housing.
- Durability: Proper play can contribute to longer bearing life by reducing stress concentration.
- Factors Affecting Play:
- Manufacturing: The clearance is determined during manufacturing by ball/roller selection.
- Fit: The fit of the bearing in the shaft and housing can affect the radial play.
- Operating Conditions: Temperature, load, and speed can influence the play.
