Bearings in the recycling industry are subject to varying levels of temperature and moisture. While conventional bearings use grease or oil to keep the rotating elements running smoothly, solid lubricant bearings, such as the NSK Molded-Oil bearings, use solid lubricants that do not require any re-lubrication.
NSK’s Molded-Oil bearings are filled with a solid, porous resin – known as Molded-Oil – which is impregnated with lubricating oil and polyolefin resin that has an affinity for oil. As the bearing rotates and the temperature increases, oil slowly seeps from the Molded-Oil and provides the required amount of lubrication for the bearing.
Tony Tormey, BSC‘s Product Manager of Industrial Bearings, says “the Molded-Oil bearings are ideal for applications where high moisture or dust could cause corrosion or grease emulsification in conventionally lubricated bearings.”
“Solid lubricant bearings such as the NSK Molded-Oil bearings have excellent performance in high-moisture and dusty environments, such as in food and beverage or recycling applications. The saturated polymer matrix that fills the inside of the bearing encapsulates the whole bearing’s cage and rolling elements and protects against entry of water or moisture during hygienic cleanings,” he explains.
As an example, bearings in the pulp and paper industry are subject to high temperature and moisture variations. The paper machines – these beasts of a machine that form the beating heart of every paper mill – take the wet fibres through multiple stages of de-watering and drying to convert them into large reels of paper. Bearings are critical to the operation of the paper machine and therefore it’s absolutely important that they work trouble-free for their expected lifespan, without causing unexpected downtimes.
A few years ago, this was the case at major Australian paper mill. NSK conducted a root cause analysis to find out why the bearings were seizing, and corrosion was seen as one potential cause for the bearings’ failure. At this stage it was decided to switch to a solid lubricant bearing and around 40 bearings were replaced with NSK Molded-Oil bearings. Since installation and over the past 10 years the plant has not had a bearing failure again.
Another application where solid lubricant bearings are recommended is in hard-to-reach applications, Tormey says.
“Depending on the plant’s layout, there may be applications where it’s difficult to regularly replenish the oil or grease in the bearing. Maybe the bearing is installed in a machine that’s placed too high for easy access or maybe the machine is installed in a remote location. In all of these scenarios, Molded-Oil™ bearings are the perfect fit as they are maintenance-free bearings,” he adds.
For applications where water wash downs increase the risk of water ingress in the bearing, Tormey recommends using suitable sealing arrangements to protect the Molded-Oil bearings.
NSK Molded-Oil bearings are available in ball bearing, wide inner ring bearings and spherical roller bearings. The ball bearing type is also available in high grade stainless steel for highly corrosive environments. NSK also offers high integrity contact seals for Molded-Oil ball bearings. NSK also offers the Molded-Oil bearings in the high-speed range with higher speed limits than the general use bearings.
David Healey, who is the Sales Engineer for NSK, says there are more advantages to using a grease-free bearing such as Molded-Oil.
“Where a bearing is to be installed on a vertical shaft, there is a risk that the oil or grease in the bearing’s housing can leak out. This problem is eliminated when a solid lubricant bearing like Molded-Oil is used,” he explains.
“Also, because Molded-Oil bearings are lubricated with very minute quantities of oil, the bearings are able to minimise any oil leakage, which makes them more environmentally friendly than greased and oiled alternatives,” he adds.
According to Healey, “solid lubrication bearings such as Molded-Oil in general, have a lower limiting speed than the equivalent sized greased bearings, when used at the allowable operational speeds and temperatures. Molded-Oil bearings have an operating life at least twice as long as grease lubricated bearings when exposed to water.”
As a national supplier of quality bearings and power transmission products, BSC has shared a strong partnership with NSK that goes back nearly 50 years.
Tormey says, “apart from being national suppliers for NSK’s products, BSC’s partnership with NSK includes conducting plant audits and store audits for customers upon request or organising training sessions when requested.”
“The BSC sales and technical representatives all have very good fundamental and practical knowledge of bearings and power transmission systems. Combining this expertise with the support we get from a global brand like NSK helps us respond to our customers’ needs efficiently,” says Tormey.