What is the order of measurement for bearings?

02 Sep.,2024

 

Ball bearings size chart

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Ball Bearing Sizes and Dimensions

Ball bearings are available in all different sizes, depending on the shaft size and requirements of the application. As they are used in all types of industries, they are needed for a large variety of application sizes, from skateboard wheels to oil drills. How are these bearing sizes determined?

 

How Bearings Are Sized

 

Bearings are measured by their inner diameter, outer diameter, and width; the size of a bearing is normally listed as such: ID x OD x W. These measurements are normally taken in millimeters, but can be converted to inches. In fact, most manufacturers and suppliers offer bearing measurements in both imperial and metric systems.

Each combination of these measurements corresponds to a series number, usually located directly on the bearing. Ball bearing size charts are widely available, and can be used to find the measurements of a specific bearing. Series and are the most commonly used, and typically range from 10 x 30 x 9 mm (.394 x 1.181 x .354 in) to 150 x 320 x 65 mm (5.906 x 12.598 x 2.559 in).

 

Series

Size Inner Dimension (mm) Outer Dimension (mm) Width (mm) Dynamic (Cr) Static (Cor) Weight (lb) 10 26 8 445 0.042 12 28 8 535 0.048 15 32 9 641 0.068 17 35 10 731 0.088 20 42 12 0.150 25 47 12 0.172 30 55 13 0.242 35 62 14 0. 40 68 15 0.407 45 75 16 0.506 50 80 16 . 55 90 18 . 60 95 18 . 65 100 18 0.957 70 110 20 1.324 75 115 20 1.404 80 125 22 1.870 85 130 22 1.958 90 140 24 2.552 95 145 24 2.662 100 150 24 2.750 105 160 26 3.498 110 170 28 4.312 120 180 28 4.796 130 200 33 7.326 140 210 33 7.832 150 225 35 9.636

 

Size Inner Dimension (mm) Outer Dimension (mm) Width (mm) Dynamic (Cr) Static (Cor) Weight (lb) 10 30 9 535 0.070 12 32 10 686 0.077 15 35 11 836 0.099 17 40 12 0.141 20 47 14 0.227 47 52 15 0.279 30 62 16 0.440 35 72 17 0.634 40 80 15 0.810 45 85 19 0.915 50 90 20 1.019 55 100 21 1.335 60 110 22 1.723 65 120 23 2.178 70 125 24 2.354 75 130 25 2.596 80 140 26 3.080 85 150 28 3.938 90 160 30 4.730 95 170 32 5.764 100 180 34 6.908 105 190 36 8.140 110 200 38 9.592 120 215 40 12.386 130 230 40 13.728 140 250 42 17.754 150 270 45 22.660

 

Series

Size Inner Dimension (mm) Outer Dimension (mm) Width (mm) Dynamic (Cr) Static (Cor) Weight (lb) 10 35 11 782 0.12 12 37 12 0.13 15 42 13 0.18 17 47 14 0.24 20 52 15 0.31 25 62 17 0.48 30 72 19 0.77 35 80 21 1.00 40 90 23 1.41 45 100 25 1.92 50 110 27 2.35 55 120 29 3.01 60 130 31 3.74 65 140 33 4.58 70 150 35 5.54 75 160 37 6.64 80 170 39 7.90 85 180 41 9.31 90 190 43 10.80 95 200 45 12.47 100 215 47 15.40 105 225 49 17.71 110 240 50 20.99 120 260 55 28.16 130 280 58 40.26 140 300 62 49.06 150 320 65 58.74

 

Series

Size Inner Dimension (mm) Outer Dimension (mm) Width (mm) Dynamic (Cr) Static (Cor) Weight (lb) 12 18 4 205 119 0.004 15 21 4 191 110 0.005 17 23 4 216 137 0.006 20 27 4 232 162 0.010 25 32 4 246 187 0.015 30 37 4 263 220 0.018 35 44 5 416 366 0.021

 

Series

Size Inner Dimension (mm) Outer Dimension (mm) Width (mm) Dynamic (Cr) Static (Cor) Weight (lb) 10 19 5 411 208 0.011 12 21 5 432 234 0. 15 24 5 468 286 0. 17 26 5 632 387 0. 20 32 7 899 555 0. 47 37 7 967 663 0. 30 42 7 821 0. 35 47 7 910 0. 40 52 7 944 0. 45 58 7 0.088 50 65 7 0. 55 72 9 0. 60 78 10 0. 65 85 10 0. 70 90 10 0. 75 95 10 0. 80 100 10 0.33 85 110 13 0. 90 115 13 0. 95 120 13 1.551 100 125 13 0. 105 130 13 0. 110 140 16 1. 120 150 16 1.441 130 165 18 2. 140 175 18 2.2 150 190 20 3.08

 

Series

Size Inner Dimension (mm) Outer Dimension (mm) Width (mm) Dynamic (Cr) Static (Cor) Weight (lb) 10 22 6 652 326 0.010 12 24 6 967 506 0.011 15 28 7 573 0.017 17 30 7 832 0.018 20 37 9 0.036 47 42 9 0.041 30 47 9 0.045 35 55 10 0.073 40 62 12 0.112 45 68 12 0.132 50 72 12 0.133 55 80 13 0.185 60 85 13 0.104 65 90 13 0.211 70 100 16 0.342 75 105 16 0.363 80 110 16 0.382 85 120 18 0.535 90 125 18 0.565 95 130 18 0.705 100 140 20 0.960 105 145 20 1.000 110 150 20 1.040 120 165 22 1.410 130 180 24 1.860 140 190 24 1.980 150 210 28 326 3.050

 

Why So Many Sizes?

 

As stated before, size depends on the shaft size and application requirements. Bearing size can greatly impact the performance and capabilities of a ball bearing; therefore different sizes are used in different industries.

 

Generally, smaller ball bearings have more limited load capacities. They are used in applications where space-efficiency is more important than load capacity. Miniature bearings, often constructed as precision ball bearings, are used for extremely small applications, such as medical instrumentation, robotics, or semiconductor equipment. On the other hand, larger bearings have greater load capacities. They are used for heavy-duty industries such as agriculture machinery, mining and drilling equipment, or heavy power tools. Many manufacturers also offer custom bearing size options for very specific applications that have unique requirements.

How to Measure Ball Bearings

 

It is not uncommon that the bearing identification number may be illegible or worn completely after long term use, requiring a bearing to be measured manually. This can easily be done using a vernier caliper to easily provide accurate measurements. If this tool is not available, measurements can be taken carefully using a ruler.

 

  1. First measure the inner diameter by inserting the outside anvils of the caliper into the inner ring of the bearing. Make sure it fits just from edge to edge, and is not tight or applying pressure on the bearing. Or, measure the inner circle of the bearing from end to end with a ruler.
  2. Measure the outer diameter by placing the bearing in the jaws of the caliper until it fits perfectly. Or, measure the bearing from one outside edge to the other using a ruler.
  3. Repeat the last step for the width of the bearing.
  4. Use a bearing size chart to find the bearing series number.

 

If you are looking for a proper bearing match or replacement, you will also need to pay attention to some other important aspects of the bearing number to find the correct bearing. The suffix can contain a few details about the bearing design and features:

 

  • Shield or seal type: The bearing may have one or two shields or seals that can be metal, rubber, or snap ring
  • Cage material: The cage can be made of brass, polyamide, steel, or other materials.
  • Internal clearance level: The bearing may require a specific amount of clearance. Usually, C2 means little clearance, no marking means standard clearance, and C3 or higher means larger clearances for bearings operating under high temperatures.
  • Grease temperature: The bearing may require grease with certain temperature capabilities.
  • Outside coatings: The inner or outer ring may be coated with a substance such as aluminum oxide for resistance to certain conditions or environments.

 

Each manufacturer may use unique suffix codes; it is best to look up a suffix guide to find the correct bearing match or replacement.

 

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Related content:

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Ball bearing types uses

How Do Ball Bearings Work

 

 

 

 

How to measure a bearing

Sometimes you may need to identify a bearing due to general wear and tear. Most bearing references now are laser stamped but these wear and rub off more quickly than the previous method, which was engraved deep in the bearing's metal.

Bearing Sizes

Each bearing has an inside diameter, outside diameter and width diameter in that order. Most bearings are metric in size, but can also be imperial. On our site, each bearing shows its principal dimensions.

d = Inside diameter
D = Outside diameter
B/T = Width diameter

You can search for a bearing entering this information on the home page in the boxes provided.

Once you have identified the bearing's code some bearings come complete with seals or shields. This is known as the suffix in the bearings reference.

Bearing Example

2RS1C3

The bearing type design that you need is a single row deep groove ball bearing with the following dimensions and suffix.

d = 25mm
D = 52mm
B/T = 15mm

Result =

The bearing also has a seal either side of the bearing.

2RS1 = 2 Rubber seals
2RSR = 2 Rubber seals
DDU = 2 Rubber seals
2Z = 2 Metal shields
ZZ = 2 Metal Shields

Result = 2RS1

And the internal clearance being C3 means that the bearing has room for expansion if needed between the races of the bearing, whilst holding the outer ring and moving the inner ring in a radial movement you will detect a little amount of play between the 2 rings. All standard clearance bearings have this movement, it may only be a small amount of movement but is controlled by international standards. C3 means the bearing has more clearance than standard.

For example we may use C3 clearance on bearings where a cold start up application my cause the balls to heat up quickly, the heat needs to go somewhere. Some of the heat gets passed through the outer race to the housing and the inner race to the shaft, this causes expansion which closes up the clearance in the bearing. If you did not allow for this clearance the bearing would not have room for expansion and lead to bearing failure.

C2 = Clearance less than normal
C3 = Clearance greater than normal
C4 = Clearance greater than C3

Result = 2RS1C3

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