Rolling Bearing Lubrication
Rolling bearing lubrication is a common industrial application that involves the use of a lubricant to keep two surfaces operating without wear and tear, while minimising the risk of damage. Lubricants provide several benefits to metal rolling bearings, including reducing friction, lubricating the surfaces, reducing heat production, and protecting against corrosion. Without these benefits, bearings would fail prematurely and suffer costly repairs or replacements.
Benefits of Rolling Bearing Lubrication
Rolling bearing lubrication provides a range of advantages to applications in industries such as motors, pumps, compressors, and wind turbines. It is the most cost-effective mean of preserving bearings from corrosion, wear and tear, and premature failure. It is often used to lubricate rolling bearings such as deep groove ball bearings, radial roller bearings, and cylindrical roller bearings.
1. Reducing Friction: Metal-metal contact between the surfaces of rolling bearings generates friction. This friction creates heat as the bearings operate and liquid lubricants reduce this friction by creating a lubricating film between the two surfaces, minimizing heat generation.
2. Lubricating Surfaces: The viscous nature of the lubricant allows it to fill the gaps between the surface particles, which produces a slippery film over the surface that reduces the resistance against motion. This lubrication increases the operational life of the bearings, reduces pressure on the bearings, and eliminates fretting corrosion.
3. Reducing Heat: Inadequate lubrication causes an increase in friction and temperature, leading to a higher risk of bearing failure. Rolling bearing lubrication provides a cooling effect by absorbing heat and dissipating it. The lubricant also prevents rapid increases in temperature and the associated adverse effects.
4. Protecting from Corrosion: Corrosion causes wear and tear and reduces bearing life. Even when protected from environmental factors, corrosion can still occur due to internal oxidation. Due to its strong adhesive characteristics, when using an appropriate rolling bearing lubricant, it creates a protective layer between the bearing metals and the environment. This layer protects the bearing surfaces and increases the bearing’s operative life.
Rolling Bearing Lubricants
A wide range of rotating bearing lubricants is available. The choice of lubricant is based on the application, environment, and the type of bearing being lubricated. This includes mineral oils such as petroleum oil, or synthetic lubricants such as polyalphaolefins (PAOs) and esters.
Petroleum Oil: It is a type of mineral oil with a viscosity VISCOTALC/Viscosity Range Classification based on the American Society for Testing and Materials ASTM D445 standard. The viscosity of petroleum oils is often specified in terms of a kinematic viscosity rather than a Saybolt Furol viscosity. Viscosity is important because it determines the load-bearing capacity of the lubricant.
Polyalphaolefins (PAOs): They are a group of synthetic chemicals derived from ethylene and are composed of long-chain hydrocarbons. They have a wide range of viscosities, making them appropriate for a variety of applications. Compared to mineral oils, PAOs offer superior oxidation stability, greater lubricity, less sludging, and better viscosity stability over a wider range of temperatures.
Esters: Also known as ester oil, they are typically composed of acids and alcohols, and offer improved oxidation stability and resistance to temperature and shear forces when compared to mineral oils and PAOs.
Conclusion
Lubrication is vital for extending the life of rolling bearings. Regular monitoring and maintenance of the lubrication system according to the manufacturer’s manual is essential for keeping the rolling bearings in a healthy condition. Choosing the right lubricant and implementing proper lubrication methods are key to obtaining the desired performance from the rolling bearing system.
