Two bearing systems are common in air moving products, sleeve bearings or ball bearings.
There are several factors that make it important to consider your choice when making a selection for your application.
Sleeve bearing fans are more economical; however, it is not recommended that they are mounted in any position other than horizontal. Temperature is another consideration; if the temperature exceeds 70°C the fan will become inoperable. The lifetime of a sleeve bearing fan is often shorter than that of a ball bearing fan, however, if the temperatures are low within the application then similar lifetime expectancy can be achieved. So if the application generates low heat or has a short life span than a sleeve bearing fan can be considered.
Ball bearing fans can be mounted in any orientation. This is because preloading of the bearings is undertaken during manufacture which is achieved with a spring or wave spring washer. The temperature operating range of ball bearing fans is greater, unlike the sleeve bearing model a standard ball bearing will operate up to 70°C and within some designs higher still. Because of this increased durability lifetime is greater and on average 50 percent. In conclusion, if the application generates high heat levels, has a longer lifespan and requires the fan to be mounted in a position other than horizontal then the design engineer should use a ball bearing fan.
Noise is often a consideration and in the past, it was thought that sleeve bearing fans ran quieter. This is true for applications that have very low speed. Yet with the improvements in preloading, ball bearing fans can work as quietly as sleeve bearing especially with applications that require faster velocities.
Lubrication is another issue, sealed for life ball bearings use thicker lubricants and additives which are less subject to evaporation. The lubricants within sleeve bearings have a greater concentration of oil, they hold less however and the system is more prone to evaporation.
Axair suggests that Ball Bearings are the more economical use but recognise that some industries and applications may be better suited to a sleeve bearing fan, especially in initial cost sensitive situations. the lifetime cost saving of using ball bearings are however still the better choice.
|Criteria||Ball Bearing||Sleeve Bearing|
|Fan Life||Longer Life||Shorter Life|
|Fan Mounting||Any||Horizontal Only|
|Noise||Quieter At High Speeds||Quieter At Low Speed|
|Lubricant||Less Evaporation||More Evaporation|
|Cost||More Expensive||Less Expensive|
For more information on Axair’s range of frame fans or to discuss the topic in depth, visit our technical page or contact our technical team on 01782 349 430.