Clearance - Bearings - Technical
Bearing Clearance
The clearance or radial play of a bearing is equal to the total radial displacement, in the median plane perpendicular to the bearing axis of the inner ring in relation to the outer ring, under the effect of a small measuring force.
Exagerated depiction of various levels of Radial Play. The starting amount is also adjusted by other factors such as housing tolerances, loads and temperature.
Because of the complexity of measurement and taking into consideration manufacturing tolerances, radial play is always indicated between two limits. The normal radial play of RMB radial ball bearings is from 6 to 15 µm (.0002 to .0006"). The normal radial play of our Japanese radial miniature ball bearings is 5 to 15 µm (.0002 to .0006"). On request, bearings may be supplied with reduced or increased radial play as per the following chart.
Play is not a criterion of the quality of a bearing but if badly chosen or unfavourably influenced during mounting, it can adversely affect the operation and even reduce the working life of a bearing.
Miniature Bearings (Less than 10mm bore size)
This table shows the basic radial clearances available for miniature bearings and applications for these clearances. Dimensions shown in microns µm 0.001mm and (1/10th’s thou 0.0001").
| SPB/ISO Code | Description | Minimum | Maximum | Applications |
|---|---|---|---|---|
| MC1 | Tight | 0 (0) | 5 (2) | Radially loaded low backlash gear systems. Very low speed. |
| MC2 | 3 (1) | 8 (3) | ||
| MC3 | Standard | 5 (2) | 10 (4) | Tape Guides, Synchros, Servo Motors, Low Speed Electric Motors and Gear Trains. Gyro Gimbals (Horizontal Axis). |
| MC4 | 8 (3) | 13 (5) | ||
| MC5 | Loose | 13 (5) | 20 (8) | High speed Electric Motors and Tape Guides. Provides some compensation for axial loading. Gyro Gimbals (Vertical Axis). |
| MC6 | 20 (8) | 28 (11) |
Bearings 10mm bore size and over
This table shows the basic radial clearances available for bearings over and including 10mm bore size. Dimensions shown in microns µm 0.001mm.
| Min / Max Clearance | |||||||
|---|---|---|---|---|---|---|---|
| Bore Size Range | |||||||
| SPB/ISO Code | Description | 10mm | Over 10mm to 18mm | Over 18mm to 24mm | Over 24mm to 30mm | Over 30mm to 40mm | Over 40mm to 50mm |
| C2 | Tight | 0 / 7 | 0 / 9 | 0 / 10 | 1 / 11 | 1 / 11 | 1 / 11 |
| CN (standard) | Standard | 2 / 13 | 3 / 18 | 5 / 20 | 5 / 20 | 6 / 20 | 6 / 23 |
| C3 | Loose | 8 / 23 | 11 / 25 | 13 / 28 | 13 / 28 | 15 / 33 | 18 / 36 |
| C4 | 14 / 29 | 18 / 33 | 20 / 36 | 23 / 41 | 28 / 46 | 30 / 51 | |
| C5 | 20 / 37 | 25 / 45 | 28 / 48 | 30 / 53 | 40 / 64 | 45 / 73 | |
You can find many types of bearings in the Small Parts and Bearings Bearings Online Catalogue pages.
For a huge range of bearings online please visit the Bearing Shop Online Website.
Hobby and Engineering Supplies lists a smaller range of products and only the most popular items in each range. They also list many additional hobby specific categories.
For the best range of miniature and small bearings please try the Miniature Bearings Australia website. Miniature Bearings Australia also list a large variety of miniature engineering products.
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