Classification and Selection Guide for Angular Contact Ball Bearings

I. Classification of Angular Contact Ball Bearings

Single-row Angular Contact Ball Bearings

• Series: It mainly includes series such as 718, 719, 70, 72, and 73. For bearings of different series with the same inner diameter, their outer diameters and thicknesses will increase sequentially.
• Features: They have a contact angle, so they are suitable for bearing axial loads or combined loads in one direction. In terms of structure, when bearing radial loads, axial components will be generated. Therefore, usually two bearings are used in an opposite arrangement, or two or more bearings are used in pairs in a duplex arrangement.
• Contact Angle: Generally, there are 15° (suffix C), 25° (suffix AC), 30° (suffix A), and 40° (suffix B), etc. The larger the contact angle is, the greater the axial force that the bearing can bear, but the rotational speed will decrease accordingly; the smaller the contact angle is, the more suitable the bearing is for high-speed and light-load occasions.

Paired Duplex Angular Contact Ball Bearings

• Definition: Bearings that combine two sets of radial bearings into a pair.
• Configuration Methods:
  • Back-to-back Configuration (Code DB): It can bear radial loads and axial loads in both directions. The distance between the action points is large, which is suitable for applications with large moment loads.
  • Face-to-face Configuration (Code DF): It can also bear radial loads and axial loads in both directions.

Double-row Angular Contact Ball Bearings

• Structure: It is a structure in which single-row angular contact ball bearings are arranged back-to-back in a duplex manner, and the inner ring and the outer ring are integrated respectively.
• Features: It can bear axial loads in both directions and has the ability to bear moment loads. It can be used as a fixed-end bearing and has the ability to bear bidirectional thrust.
• Contact Angle: Usually 30°.

Four-point Contact Ball Bearings

• Structure: It is a single-row angular contact ball bearing with a separated inner and outer ring. The inner ring is divided into two parts, so one bearing can bear axial loads in both directions.
• Contact Angle: 35°. It has a large axial load capacity and is suitable for bearing pure axial loads or combined loads with large axial loads.

Thrust Angular Contact Ball Bearings

• Features: The two-way thrust angular contact ball bearings are used in combination with double-row cylindrical roller bearings and can bear two-way axial loads.

Ball Screw Support Bearings

• Features: They are one-way thrust angular contact ball bearings with a contact angle of 60°, which are particularly suitable for the support of high-speed precision CNC machine tools.
• Series: Common series include 7602 (standard metric system), 7603 (standard metric system), BS (non-standard metric system), and BSS (non-standard inch system) series.

II. Selection of Angular Contact Ball Bearings

Selection According to Working Conditions

• Working Environment: Consider the working environment in which the bearing will be located, such as temperature, humidity, and corrosive media.
• Accuracy Requirements: If the accuracy requirement for the shaft is high, such as for the spindle of a machine tool, a bearing with a higher tolerance grade (such as P4 or P2 grade) should be selected.
• Rotational Speed: If a high rotational speed is required, a light series bearing with a smaller contact angle (such as a 15° contact angle) should be selected; if a large axial load needs to be borne, a bearing with a larger contact angle (such as a 40° contact angle) can be selected.
• Direction and Magnitude of the Load: Select the appropriate bearing type and configuration method according to the magnitude and direction of the radial and axial loads that the bearing will bear.

Selection According to Dimensions and Rotational Accuracy

• Dimensions: Select the appropriate outer diameter, inner diameter, and thickness of the bearing according to the size of the shaft and the space limitations of the bearing installation part.
• Rotational Accuracy: Angular contact ball bearings have four rotational accuracy indicators (outer diameter runout, inner diameter runout, outer end runout, and inner end runout), and the appropriate accuracy grade should be selected according to the usage scenario and cost budget.

Selection According to the Material and Type of the Cage

• Cage Material: Common materials include brass, synthetic resin, machined steel, etc., and the appropriate material should be selected according to the bearing form and usage conditions.
• Cage Type: Select the appropriate cage type according to the rotational speed, load, and working environment of the bearing to ensure the running stability and service life of the bearing.