Bearing Installation Knowledge

The quality of bearing installation will affect the bearing’s accuracy, life and performance. Therefore, please fully study the installation of the bearing, that is, please install the bearing according to the operating standards including the following items.

1. Clean the bearing and related parts

For grease-lubricated bearings and bearings with oil seals or dust covers on both sides, the seal ring does not need to be cleaned before installation.

2. Check the size and finishing of related parts
3. Installation method

The installation of bearings should be based on the bearing structure, size and matching properties of bearing components. The pressure should be directly applied to the end face of the tight-fitting ring, and the pressure should not be transmitted through the rolling element. The following methods are generally used for bearing installation:

a. Press-fit

When the inner ring of the bearing is tightly fitted with the shaft and the outer ring is loosely fitted with the bearing seat hole, the bearing can be pressed onto the shaft with a press, and then the shaft and the bearing are installed into the bearing seat hole together. When pressing, a soft metal sleeve (copper or soft steel) is placed on the end face of the inner ring of the bearing. The inner diameter of the sleeve should be slightly larger than the diameter of the shaft neck, and the outer diameter should be slightly smaller than the inner ring rib of the bearing to avoid pressing on the retainer. When the outer ring of the bearing is tightly fitted with the bearing seat hole and the inner ring is loosely fitted with the shaft, the bearing can be pressed into the bearing seat hole first. At this time, the outer diameter of the sleeve should be slightly smaller than the diameter of the seat hole. If the bearing ring is tightly fitted with the shaft and the seat hole, the inner and outer rings should be pressed into the shaft and the seat hole at the same time when installing the indoor ring. The structure of the assembly sleeve should be able to simultaneously press the end faces of the inner and outer rings of the bearing.

b. Heating fit

This is an installation method that converts tight fit into loose fit by heating the bearing or bearing seat and using thermal expansion. It is a common and labor-saving installation method. This method is suitable for the installation of bearings with large interference. Before hot installation, put the bearing or the ring of the separable bearing into the oil tank and heat it evenly to 80-100℃, then take it out of the oil and install it on the shaft as soon as possible. To prevent the inner ring end face and the shaft shoulder from not fitting tightly after cooling, the bearing can be axially tightened after cooling. When the outer ring of the bearing is tightly fitted with the light metal bearing seat, the hot installation method of heating the bearing seat can avoid scratches on the mating surface. When heating the bearing with an oil tank, there should be a mesh grid at a certain distance from the bottom of the tank, or the bearing should be hung with a hook. The bearing cannot be placed on the bottom of the tank to prevent impurities from entering the bearing or uneven heating. There must be a thermometer in the oil tank, and the oil temperature must be strictly controlled not to exceed 100°C to prevent the tempering effect and reduce the hardness of the ring.

c. Installation of tapered bore bearings

Tapered bore bearings can be directly installed on the taper of the shaft neck, or on the tapered surface of the adapter sleeve and the withdrawal sleeve. The tightness of the fit can be measured by the reduction in the radial clearance of the bearing. Therefore, the radial clearance of the bearing should be measured before installation, and the clearance should be measured frequently during installation to achieve the required clearance reduction. The locking nut is generally used for installation, and the heating installation method can also be used.

d. Installation of thrust bearings

The fit between the thrust bearing and the shaft is generally a transition fit, and the fit between the seat ring and the bearing seat hole is generally a clearance fit. Therefore, this type of bearing is easier to install. The center shaft spring of the bidirectional thrust bearing should be fixed on the shaft to prevent rotation relative to the shaft. The installation method of the bearing is generally that the shaft rotates, so the fit between the inner ring and the shaft is an over-fit, and the fit between the outer ring and the bearing chamber is a clearance fit.

4. Inspection after bearing installation
5. Adding lubricant