BEARING LUBRICATION BASIC INFORMATION AND TUTORIALS

Since the lubricant affects bearing life and operation, selecting the proper lubricant is an important design function. The purpose of lubrication in bearing applications is to:

1. Minimize friction at points of contact within the bearings

2. Protect the highly finished bearing surfaces from corrosion

3. Dissipate heat generated within the bearings

4. Remove foreign matter or prevent its entry into the bearings

Two basic types of lubricants used with antifriction bearings are oils and greases. Each has its advantages and limitations.

Since oil is a liquid, it lubricates all surfaces and is able to dissipate heat from these surfaces more readily. Because oil retains its physical characteristics over a wider range of temperatures, it may be used for high-speed and high-temperature applications.

The quantity of oil supplied to the bearing may be accurately controlled. Oil lubricants can be circulated, cleaned, and cooled for more effective lubrication. Grease, which is easier to retain in the bearing housing, aids as a sealant against foreign matter and corrosive fumes.

Bearing Oil Lubrication

1. Oil is a better lubricant for high speeds or high temperatures. It can be cooled to help reduce bearing temperature.

2. Oil is easier to handle, and with oil it is easier to control the amount of lubricant reaching the bearing. It is harder to retain in the bearing. Lubricant losses may be higher than with grease.

3. As a liquid, oil can be introduced into the bearing in many ways, such as drip feed, wick feed, pressurized circulating systems, oil bath, or air-oil mist. Each is suited to certain types of applications.

4. Oil is easier to keep clean for recirculating systems.

Bearing Grease Lubrication

1. This type of lubrication is restricted to lower-speed applications within the operatingtemperature limits of the grease.

2. Grease is easily confined in the housing.This is important in the food, textile, and chemical industries.

3. Bearing enclosure and seal design is simplified.

4. Grease improves the efficiency of mechanical seals to give better protection to the bearing.

For all new applications, a competent bearing or lubrication engineer should be consulted to recommend the specific lubricant and method of lubrication for the specific bearing’s operating and ambient conditions.

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