Bearings And Steel Balls

Designation of the rolling bearings, bearing abbreviations and selection of rolling bearings

Designation of the rolling bearings

The outer dimensions of the rolling bearings are set forth in DIN 616 in accordance with DIN ISO 355. They are designed so that several outer diameters and widths are assigned to each bearing bore to provide a large range of load capacity for bearings with the same bore and design.

This designation system is also set forth in DIN 623. A distinction is made between and the width rows: the diameter rows: 0 (very light) 0 2 (light) 1 3 (medium) 2 4 (heavy) 3 These relations are made clear in the following graphic. It should, however, be kept in mind that the standardized bearing designations do not correspond to this system in all cases.

Bearing abbreviations

A bearing abbreviation consists of numbers or of letters and numbers. The first number or letter group indicates the bearing design (deep groove ball bearing, tapered roller bearing, self-aligning roller bearings, etc.) and the width and diameter row (light, medium, heavy, etc.); the second number group indicates the bore code.

The size of the bore of the bearing is a function of the multiplication of the code by 5 (above a bore diameter ≥ 20 mm). The bearing designations without the added designation indicate normal bearings, for instance with normal size, shape and run accuracy in accordance with the tolerances in DIN 620. Deviations are described by the added designations. These prefixes indicate bearing components (rings, cages), while suffixes indicate special aspects of the interior construction, size tolerances, run accuracy, bearing clearance, etc. Prefixes Prefixes are used very rarely. They normally mark single parts of complete bearings. Suffixes Suffixes mark special models that deviate from the standard. In particular, they include information about:

  • interior design
  • outer shape
  • bearing clearance
  • cage model
  • lubricant
  • tolerances
  • seals

Selection of rolling bearings

The design engineer can select the best type of bearing based on the characteristic properties of the various types of roller bearings and the operating conditions of the arrangement of the bearings. Here, the special or most important conditions of each case for the bearings that could influence the selection of the best bearing for the task are to be taken into consideration. Various types of bearings may be best for the given operating conditions in many cases.

The effective outer forces and the demands for service life and operating safety determine the size of the bearing needed. Above all, the decisive factors for the selection of the type and size of the bearing are the size, direction and type of loads that will be exerted on the bearing and the operating speed.

Space limitations often require the selection of bearings with small cross-sections or even multiple rows of bearings to attain the necessary load-bearing capacity and service life. If the bearings have to be very accurate, bearings with great accuracy, especially ball bearings and cylinder roller bearings, should be used as they are produced in the highest accuracy classes. The operating temperature of the bearings influences the design of the arrangement of the bearings both from the viewpoint of the selection of lubricant and the model of the bearing when the operating temperature continually rises above 100°C.

The inner bearing clearance must be suited to the operating conditions, which are mostly determined by the temperature difference between the inner and outer ring, by the effects of the heat fed to the bearing, or by the effect of the high speed. Furthermore, the selection of the bearing is also influenced by the simplicity of the installation, demands on lubrication and seals, and demands for low friction and low running noise. A distinction is made for roller bearings between static and dynamic loads.