Explaination of bearing parameters

All kind of letters printed by manufacturers on bearings have their own meaning that can help you to understand its characteristics and bearing types. So what is the basic meaning of parameters printed on bearings?

Each type of bearings are printed with different numbers and characters. Depending on manufacturers and particular characteristics, each bearing code will be printed differently, eventhough they all have to be based on the same general principles which must be complied by all manufacturers.

Basic meaning of printed parameters on bearings is divided into 2 categories: commercial specification and technical specification.

Commercial specification

1. Branding:

All products in general - not only bearings must clearly state its brand name and origin if they want to join the global trade. 
A same product might have a lot of different manufacturers. Brand recognition is clearly distinguishable by consumers as about which manufacturers produced that product.
Branding can be either a logo or the abbrevation of the brand, for example INA-FAG, NSK, Timken, Koyo...

2. Origin:

The origin printed on bearings will help us to understand which country this product is produced from. Many manufacturers place their production lines in countries with low labor and production costs. These products are strictly compliant with manufacturer's quality control regulations. 
For example, INA bearings can also be manufactured in China, TIMKEN bearings can be manufactured in Pakistan...

Hình 2: Vòng bi thương hiệu INA của Đức được sản xuất tại Mỹ

3. Date of manufacture:

Depending on manufacturers and types of bearing on which production date is printed or not. Production date is not required to be printed on bearings.
For example, with bearings which are too small, the manufacturer will print production date on their packaging instead of on bearings.

Technical specification

Technical specification helps us to choose the products as desired, but not everyone knows that. Commercial specifications may not be fully printed but technical specifications must be printed on bearings.

1. Bearing Size:

The last two digits indicate only the inner diameter of the bearings from 00-99 (20mm<D<5000mm). 
Some types of bearings used in super-large machines may have an internal diameter (D) greater than 5000mm. 
And some bearings used in micro machines (commonly in medical dentistry) may be less than 20mm.

For example: Bearing 2315
We will take the last two digits multiplied by 5: We have 15x5 = 75mm. It means that the inner diameter is D = 75mm (diameter of the ball hole).

Bearing 304
We have 04 x 5 = 20mm. The inner diameter is 20mm.
So from 04 upward, we will multiply by 5. 
From 04 downward, we have the corresponding special symbol as following: 00:10mm, 01:12mm, 02:15mm, 03:17mm. 
This is the basic knowledge that you need to choose the right products. 

Hình 3: Vòng bi Koyo luôn được in đầy đủ thông số kỹ thuật và thương mại

2. Bearing Load Capacity:

Notice the 3rd character from right to left, meaning as following:

- No.1 or No.7: Super light load
- No.2: Light load
- No.3: Average load
- No.4: Heavy load
- No.5: Super heavy load
- No.6: Average load like No.3 but thicker
- No.8-9: Extreme light load; 814, 820, 914

3. Bearing Types:

The 4th letter from right to left is denoted by 1 - 9. They mean the following:
Symbol No.0: Single-row ball bearings
Symbol No.1: Double-row ball bearings
Symbol No.2: Single-row cylindrical roller bearings
Symbol No.3: Double-row cylindrical roller bearings
Symbol No.4: Single-row tapered roller bearings
Symbol No.5: Tapered roller thrust bearings
Symbol No.6: Spherical roller bearings
Symbol No.7: Tapered roller bearings
Symbol No.8: Thrust ball bearings
Symbol No.9: Spherical thrust roller bearings

4. Bearing Structure:

The meaning of the 5th letter from right to left:
3: Single-row cylindrical roller bearings without barrier
4: Same as 3 but the block has a barrier
5: 1 spot for mounting the locks on the outer ring
6: a black oil block
8: 2 black oil blocks
9: Single-row cylindrical roller bearings with a ring that blocks the rollers in the inner ring.

For example: Bearing 60304
- Inner ring: 04*5 = 20mm
- Average Load Capacity
- Single-row ball bearings
- has a black oil block

Note: For bearings with only 3 digits, the last number is the diameter of the bearings (D<20mm).
For example: Bearing 678
- Inner ring D=8mm, light load capacity, thrust ball bearings.

5. Bearing Clearance variation:

6. Shaft Gap variation:

Nguồn: Tổng hợp