The relubrication intervals t_f for bearings with rotating inner ring on horizontal shafts under normal and clean conditions can be obtained from diagram 4 as a function of

The relubrication interval t_f is an estimated value, valid for an operating temperature of 70 °C, using good quality lithium thickener/mineral oil greases. When bearing operating conditions differ, adjust the relubrication intervals obtained from diagram 4, according to the information given under "Adjustments of relubrication intervals due to operating conditions and bearing types".

If the speed factor A exceeds a value of 70% of the recommended limit according to table 2 or if ambient temperatures are high, then the use of the calculations presented in the section "Speeds and vibration" is recommended to check the operating temperature and the proper lubrication method.

When using high performance greases, a longer relubrication interval and grease life may be possible. Contact the SKF application engineering service for additional information.

Estimation of the relubrication interval can be made with the program "Relubrication intervals".

The relubrication interval t_f may be extended at temperatures below 70 °C if the temperature is not close to the lower temperature performance limit (diagram 1, LTPL). A total extension of the relubrication interval t_f by more than a factor of two is not recommended. In case of full complement bearings and thrust roller bearings, t_f values obtained from diagram 4 should not be extended.

Moreover, it is not advisable to use relubrication intervals in excess of 30 000 hours.

For many applications, there is a practical grease lubrication limit, when the bearing ring with the highest temperature reaches an operating temperature of 100 °C. Above this temperature special greases should be used. In addition, the temperature stability of the bearing and premature seal failure should be taken into consideration.

For high temperature applications please consult the SKF application engineering service.

Vertical shaft
For bearings on vertical shafts, the intervals obtained from diagram 4 should be halved. The use of a good sealing or retaining shield is a prerequisite to prevent grease leaking from the bearing arrangement.

Vibration
Moderate vibration will not have a negative effect on grease life, but high vibration and shock levels, such as those in vibrating screen applications, will cause the grease to churn. In these cases the relubrication interval should be reduced. If the grease becomes too soft, grease with a better mechanical stability, e.g. SKF grease LGHB 2 or grease with higher stiffness up to NLGI 3 should be used.

Outer ring rotation
In applications where the outer ring rotates, the speed factor A is calculated differently: in this case use the bearing outside diameter D instead of d_m. The use of a good sealing mechanism is a prerequisite in order to avoid grease loss.

Under conditions of high outer ring speeds (i.e. > 40% of the reference speed listed in the product tables), greases with a reduced bleeding tendency should be selected.

For spherical roller thrust bearings with a rotating housing washer oil lubrication is recommended.

Contamination
In case of ingress of contamination, more frequent relubrication than indicated by the relubrication interval will reduce the negative effects of foreign particles on the grease while reducing the damaging effects caused by overrolling the particles. Fluid contaminants (water, process fluids) also call for a reduced interval. In case of severe contamination, continuous relubrication should be considered.

Very low speeds
Bearings that operate at very low speeds under light loads call for a grease with low consistency while bearings that operate at low speeds and heavy loads need to be lubricated by high viscosity greases, and if possible, with very good EP characteristics.

Solid additives such as graphite and molybdenum disulphide (MoS₂) can be considered for a speed factor A < 20 000. Selecting the proper grease and grease fill is very important in low speed applications.

High speeds
Relubrication intervals for bearings used at high speeds i.e. above the recommended speed factor A provided in table 2 only apply when using special greases or modified bearing executions, e.g. hybrid bearings. In these cases continuous relubrication techniques such as circulating oil, oil-spot etc, are more suitable than grease lubrication.

Very heavy loads
For bearings operating at a speed factor A > 20 000 and subjected to a load ratio C/P < 4 the relubrication interval is further reduced. Under these very heavy load conditions, continuous grease relubrication or oil bath lubrication is recommended.

In applications where the speed factor A < 20 000 and the load ratio C/P = 1-2, reference should be made to the information under "Very low speeds". For heavy loads and high speeds circulating oil lubrication with cooling is generally recommended.

Very light loads
In many cases the relubrication interval may be extended if the loads are light (C/P = 30 to 50). To obtain satisfactory operation the bearings should be subjected to at least the minimum load as stated in the  relevant product sections.

Misalignment
A constant misalignment within the permissible limits does not adversely affect the grease life in spherical roller bearings, self-aligning ball bearings or toroidal roller bearings.

Large bearings
To establish a proper relubrication interval for line contact bearings, in particular large bearings (d > 300 mm) used in critical bearing arrangements in process industries, an interactive procedure is recommended. In these cases it is advisable to initially relubricate more frequently and adhere strictly to the recommended regreasing quantities, see section "Relubrication procedures".

Before regreasing, the appearance of the used grease and the degree of contamination due to particles and water should be checked. Also the seal should be checked completely, looking for wear, damage and leaks. When the condition of the grease and associated components is found to be satisfactory, the relubrication interval can be gradually increased.

A similar procedure is recommended for spherical roller thrust bearings, prototype machines and upgrades of high-density power equipment or wherever application experience is limited.

Cylindrical roller bearings
The relubrication intervals from diagram 4 are valid for cylindrical roller bearings fitted with

For cylindrical roller bearings with

the value for the relubrication interval from diagram 4 should be halved and a grease with good oil bleeding properties should be applied. Moreover, grease lubricated bearings with a MA, MB, ML or MP cage should not be operated at speeds exceeding the speed factor A = nd_m = 250 000. For applications exceeding this value, please consult the SKF application engineering service. SKF generally recommends to lubricate these bearings with oil.

and, last but not least, a more suitable grease should be considered.