Seals, Bearings and Lubrication Special Focus June/July 2025 www.pwemag.co.uk Plant & Works Engineering | 39 where lubricant retention would otherwise be a challenge. However, grease also has its limitations. It doesn’t dissipate heat as efficiently as oil and can break down faster in high-speed or hightemperature environments. In such cases, excessive heat can cause the thickener to degrade, which reduces lubrication effectiveness and potentially damages the bearing. When oil is the better fit Oil is often favoured in very high-speed or low torque applications where better cooling and continuous circulation are needed. Unlike grease, oil can be pumped, filtered and monitored as part of a closed lubrication system — which allows contaminants to be removed and fresh lubricant to be supplied continuously. Typical examples include gearboxes, machine tools and high-speed spindles. In these cases, the superior heat transfer properties of oil reduce the risk of thermal damage and prolong bearing life. Oil also provides lower friction in many situations, making it well-suited to precision applications that demand tight tolerances and consistent performance. That said, oil systems are more complex and require careful design. They need pumps, reservoirs, filtration units and regular monitoring. Some applications require a continuous oil mist or oil spray — all of which add to maintenance requirements and cost. They’re also less effective in vertical or exposed environments where leakage or oil migration can become problematic. Key factors in the decision Several operating parameters should guide the decision between grease and oil lubrication, each with a direct impact on bearing performance. Speed is one of the most critical considerations — as rotational speed increases, so does friction and heat. In many high-speed applications, oil is preferred for its ability to circulate and dissipate heat more effectively than grease. Temperature is another key factor. In environments where bearings are exposed to elevated operating or ambient temperatures, oil typically provides better thermal stability and cooling capacity with much less resistance than high temperatures greases. Heavily loaded systems may benefit from oil’s superior film strength and flow characteristics, though grease formulations with extreme pressure additives can also perform well in low-speed, high-load conditions. In environments where contamination is a concern — such as dusty, wet or chemically aggressive settings — grease tends to be the better option, as its consistency helps seal out harmful debris and moisture. Finally, maintenance accessibility must be considered. In applications where regular relubrication is difficult or impractical, sealed bearings pre-filled with grease offer a more reliable and maintenance-free solution. Finding the right balance Ultimately, the choice between grease and oil comes down to balancing performance needs with practical constraints. Grease offers simplicity, sealing and lower maintenance — ideal for many standard industrial and automotive applications. Oil, on the other hand, delivers superior cooling and lubrication under extreme conditions but requires a more involved setup and monitoring process. By carefully assessing the demands of the application and understanding the strengths and limitations of each lubrication type — engineers and maintenance teams can make informed decisions that improve bearing life, reduce downtime and optimise operational efficiency. For further information please visit: http://www.smbbearings.com/
RkJQdWJsaXNoZXIy MjQ0NzM=