For optimal performance and maximum service length, you need to lubricate rolling bearings. Lubrication is essential as it will affect the life, noise, speed, torque, grease migration out gassing, temperature and corrosion of the ball or roller bearings.
The greasing frequency and quantity for each application (bearing size, speed, temperature, etc) will vary. Many people think that any lubricant will do, but that is a myth that can cause lots of problems with your equipment.
Which lubrication method is right for your application? There are three basic types of lubricants available each has its own characteristics that may or may not apply to your specific application.
When choosing a lubricant for rolling element bearings, the lubricant should be able to maintain a stable viscosity over a wide range of temperatures and have the strength to support loads.
Oil: Oil is a very common lubricant and is recommended when your application needs very low torque or a smaller range of torque variation. Each application will determine if an oil lubricant is optimal. Petroleum based and synthetic oils are choices. (Silicone, diester compounds and fluorinated compounds are examples of synthetic oil products.)
Oiled bearings exhibit lower start up and running torque, but have higher speed capabilities. Because oil is prone to higher evaporation, they don't last as long as a grease product. Temperature range, viscosity, and the rate of evaporation are important factors when choosing an oil for your application.
Grease: Grease is just a thicker version of oil. A thickener such as metal soaps or elements such as lithium, sodium, aluminum, calcium, organic or inorganic compounds, are added to oil. However, these grease versions can have performance improving additives. These additional compounds can be anti-corrosives, fillers, fortifiers, and pressure fortifiers. When selecting a grease, you must consider the viscosity and temperature range of the grease.
Solid Films: Films are used in applications when grease or oil cannot tolerate the environment, be it a vacuum, radiation or high temperatures. Solid film lubricants are characterized as dry film or solid film lubricants. Graphite and Teflon are the most commonly used films for machinery lubrication, but they can also be made of gold, silver, or chrome to name a few.
The type of lubricant and the amount applied will impact the maximum operating speed and torque for starting and running. Miniature and instrument bearings are many times only lubricated once in their lifetime.
Larger bearings are often lubricated frequently during the maintenance of the rotating machinery. They are often lubricated via oil re-circulation systems that are part of the equipment design.
You can read more about bearing lubrication from Baldor Motors http://www.powertransmission.com/issues/0916/bearing_briefs.pdf.
IER Services (Industrial Electromechanical Repair Services) provides fast, effective, repair services of electromechanical devices of all types including AC and DC motors, pumps, ball bearings, variable frequency drives, and more. We keep your rotating machinery running smoothly. Call us with any questions you may have about lubricating your rolling bearings. 614.298.1600