What Is a Dry Bearing?
Dry bearing is a type of bearing that can be used without lubrication by impregnating the bearing body with lubricating oil, embedding individual lubricants, or using self-lubricating materials.
Generally, a bearing has a ball between the inner and outer rings, and the ball rolls. Lubricating oils such as oil and grease are applied to these bearings to reduce resistance to rotation and to prevent wear due to friction between the balls and the inner and outer rings.
Applications of Dry Bearings
More than 100 dry bearings of about 30 different types are used in a single automobile, such as in power steering systems.
Dry bearings can be used in severe environments such as wind power generation facilities, where maintenance is difficult due to their elevated location, and offshore oil field facilities, where corrosion risk due to seawater is high.
Because they do not contain oil or grease, they are used to hold rotating parts in vacuum, in places where outgassing is undesirable, and underwater.
It is difficult to apply to locations where high-speed rotation and high rotational accuracy are required, and is often used in locations where rotational accuracy is not required at low speeds.
Principles of Dry Bearings
Because they are oilless bearings, they can be used in vacuum, underwater, at high temperatures, and in places where maintenance is not possible.
They are inexpensive, have a large lineup, and range in size from quite small. Materials are not only metal but also plastic, including fluorine-based resin that can be used in areas where chemical resistance is required.
Among dry bearings, there are a large number of dry bearings on the market that can be selected according to the application and are resistant to specific elements such as vibration resistance and heat resistance.
Graphite or molybdenum disulfide is added as a lubricant in metal dry bearings, while self-lubricating materials such as POM are used in plastic dry bearings.
General-purpose dry bearings made of POM (polyacetal), which has good sliding properties, can be obtained for a cheap price.
Dry bearings are sometimes called oilless bearings because of their characteristics oilless.