Bearings with Solid Oil

Solid Oil filled SKF products

SKF bearings with Solid Oil are designed for use in applications where high levels of moisture and incidental contact with water and other contaminants are real issues. Bearings with Solid Oil are lubricated for the life of the bearing and cannot be relubricated.

Solid Oil:

is an oil saturated, polymer material

moulded into the bearing, forming very narrow gaps between the rolling elements, raceways and cage(s), enabling the bearing to rotate freely

having a porous structure, with millions of micro-pores that retain the lubricating oil by surface tension

virtually fills all of the free space in the bearing

releases oil into the narrow gaps, during operation, providing effective minimum quantity lubrication

Bearing features

Long service life

An increase in operating temperature pushes the oil toward the surface of the polymer material, supporting consistent lubricant supply. During shutdown, any excess oil is re-absorbed back into the polymer material.

Extended lubricant life

With Solid Oil bearings, a large amount of oil is available (two to four times more compared to conventional grease fill).

The Solid Oil polymer structure eliminates lubricant churning.

Solid Oil is a high-quality synthetic oil that resists oxidation.

Resists washout

Solid Oil cannot be washed out and virtually fills all free space, limiting the amount of wet contamination that can enter the bearing.

Water cannot mix with the oil or Solid Oil polymer.

Virtually eliminates lubricant leakage

Solid Oil retains oil in the bearing.

Integral bearing seals further increase the oil retention.

Protects against the ingress of contaminants

Close osculation between Solid Oil and the rolling elements and raceways significantly reduces the ingress of contaminants.

Solid Oil provides additional support for integral bearing seals.

Designs and variants

fig. 1

The SKF standard assortment of bearings and bearing units with Solid Oil (fig. 1) includes:

Deep groove ball bearings

Spherical roller bearings

Insert bearings and ball bearing units

Tapered roller bearings

Cylindrical roller bearings

Self-aligning ball bearings

On request, SKF can supply other bearing types with Solid Oil to meet the needs of a particular application, except for CARB toroidal roller bearings which are unsuitable for use with Solid Oil. Bearings fitted with a large-volume cage are not suitable for Solid Oil because there is too little free space inside the bearing.

Solid Oil variants

Standard variant (designation suffix W64, table 1)

contains a high-quality synthetic oil

meets the needs of most applications

Food-grade variant (designation suffix W64F, table 1)

contains an oil registered by NSF as a category H1

meets the needs of food applications

Sealed bearings

with integral contact seals are strongly recommended in wet environments

with Solid Oil increase the sealing effectiveness, as the Solid Oil supports the seals axially, preventing them from deflecting and opening under pressure

For information about sealing options, contact the SKF application engineering service.

Where carbon steel bearings are exposed to wet environments, additional external seals are recommended to protect the bearing’s external surfaces from corrosion.

Bearing data

Dimension standards, tolerances, internal clearance

Refer to Bearing (unit) data in the relevant product section of the standard bearing (unit).

Loads

Load carrying capacity

The basic dynamic and static load ratings for bearings with Solid Oil are the same as for corresponding SKF standard bearings.

Temperature limits

The permissible operating temperature for bearings with Solid Oil can be limited by:

the dimensional stability of the bearing rings and rolling elements

the cage(s)

the seals

the Solid Oil

For limits of bearing rings, rolling elements, cage(s) and seals, refer to Temperature limits of the relevant product section of the standard bearing.

The relevant limits for Solid Oil are listed in table 1.

Where temperatures outside the permissible range are expected, contact SKF.

Speed limits

The recommended speed values for bearings and bearing units with Solid Oil (table 2), operating in an ambient temperature of 20 °C (70 °F), are limited by the maximum continuous operating temperature of 85 °C (185 °F). Ambient temperature is the temperature closest to the bearing position, not necessarily room temperature.

For bearing types or variants not listed in table 2, contact the SKF application engineering service.

For ambient temperatures above 20 °C (70 °F), the speed limit should be reduced using the reduction factor f_T (diagram 1).

Calculation example

A deep groove ball bearing 6208/W64 is to operate at an ambient temperature of 50 °C (120 °F). What is the reduced speed limit?

Recommended speed limit for 20 °C (70 °F) ambient temperature

From table 2: speed value nd_m = 300 000 mm/min (single row deep groove ball bearing with a stamped metal cage)

Dimensions: d = 40 mm, D = 80 mm

n = 300 000 / d_m = 300 000 / (0,5 (40 + 80)) = 5 000 r/min

Reduction for 50 °C (120 °F) ambient temperature

From diagram 1: speed reduction factor f_T ≈ 0,53

n_reduced = 5 000 f_T = 5 000 x 0,53 = 2 650 r/min

Friction characteristics

The friction characteristics of a bearing with Solid Oil correspond to the relevant SKF standard bearing except that the Solid Oil polymer filling adds a fixed friction.

Mounting

If a bearing with Solid Oil is to be hot mounted, it should be heated to a maximum of 120 °C (250 °F) by using an induction heater.

Heating plates or heated oil baths should not be used.

Designation system

Refer to Designation system in the relevant product section of the standard bearing/unit.

The designation suffixes used to identify bearings with Solid Oil are explained in the following:

W64	Synthetic base oil type, standard variant
W64F	Synthetic base oil type, NSF H1 approved for food applications