Lubrication Systems: Single-Point Lubricator & Solid Lubrication
Bearings require quality lubrication practices to maximize their operational life. Manual greasing is and always has been easy to perform incorrectly. The greasing process contains many variables that, when done incorrectly, lead directly to bearing failure. Many applications and industries operate on the function and reliability of bearings. Fortunately, reliable lubrication systems are viable options.
Single-point lubricators (SPLs) are mechanical or electrically powered greasing options. Still relying on grease, these small components utilize lubrication lines or attach directly to bearings. They intend to provide a more uniform grease application than the intermittent and varying grease quantities produced by manual greasing.
SPLs aren’t without their faults, though. One study shows that lubrication-related issues lead to approximately 80% of premature bearing failures, few of which these lubricators address.
Can solid lubrication produce the same benefits that SPLs do? Is solid lubrication a superior bearing lubrication method? Read on to find out.
Single-point lubricators and grease
Most premature bearing failures are due to lubrication. The lesson here is that lubrication is critical to the performance and longevity of a bearing.
Nearly 90% of bearing applications rely on grease for lubrication. Grease issues – excessive moisture, contamination, incorrect viscosity, incompatibility, over or under-greasing – contribute to most lubrication-related bearing failures.
SPLs reduce the potential for these issues, but cannot eliminate them. SPLs will always need their lubricant refilled. Without a project management system’s assistance to aid maintenance technicians with a relubrication schedule, lubricators may become forgotten and run dry.
Mistakenly using an incompatible grease or allowing contaminants to enter the lubricator during refills will still remain a possibility. Anything introduced to the bearing’s interior circulates with the grease, causing damage to the rolling elements, leading to failure.
Solid lubrication does not pose the same risks. Solid lubricants use the oil contained within the polymer to lubricate. With no relubrication necessary, incompatibilities and contaminated greases are a thing of the past.
Grease is also a continual expense. Bearings installed with solid lubrication can eliminate this cost (as well as increase profits) and the inconsistencies it brings to ongoing maintenance.
SPLs and the uniform application of lubricants
SPLs allow maintenance technicians to extend the time between their involvement while knowing that bearings will continue to receive the grease they require to operate. These products will only delay, not eliminate, inevitable interaction.
Most SPLs have options for the frequency and quantity of grease that gets delivered to a bearing over time. These SPLs operate with screws or springs, slowly pushing grease into the bearing. It is very linear in delivery, with little to no quantity variation.
This method has an issue: forcing all bearing bore sizes, rotations per minute, application environments, and operating temperatures into a small set of grease delivery quantities.
Most major bearing manufacturers have several relubrication intervals dependent on the above factors, some with twice as many options as available with SPLs. Even if a majority of bearings do fit within these intervals, what about the remaining bearings?
Over or under-lubrication will be the result. Over-lubrication leads to “churning,” where the rolling elements have to fight through the grease rather than providing an ideal film between the element and race. This causes heat to build in the bearing and premature failure to occur. Under-lubrication causes metal-on-metal contact, which is a direct path to bearing failure.
SPLs may fit some bearings’ lubrication schedules, but the system is far from perfect for others.
Solid lubrication avoids all of this. Bearings that include this technology cannot be lubricated incorrectly. It has lubrication on-demand, containing up to four times the amount of base oil that a greased bearing would. No more under or over-lubricating. No more lubrication schedules, approximations, or guesswork. The bearing uses the oil that it needs, and once at rest, the polymer reabsorbs it.
SPLs and the possibility of damage
SPLs reduce the active maintenance typically required of greased bearings. You can set these tools to work quietly behind the scenes, relying on them to serve a lubrication system’s critical function.
Many SPLs connect directly to the housings, while others utilize grease lines to make them more accessible or keep them from being damaged. However, SPLs will always be vulnerable to damage and failure. It doesn’t take much to damage a grease line, and the majority of SPLs are plastic. Some require batteries to keep them operational.
SPLs do create easier access to lubrication for bearings that are difficult to reach. If a manually lubricated bearing happens to fail in a location like this, it becomes necessary to shut-down production, which may very well cause losses.
To avoid these situations, it becomes necessary to visually inspect the lubricators and lines frequently to ensure that grease is still flowing to the bearings. Can we trust these vulnerable components to operate with 100% certainty?
Bearings with solid lubrication have no external components to damage. Housings no longer have grease zerks, and the bearings have no lubrication grooves on their outer races. The polymer will never fail to deliver oil, nor can the process be accidentally interrupted. Bearings with solid lubrication are lubricated for life.
SPLs and solid lube: similar but not the same
Both of these bearing lubrication systems strip down relubrication to something much more basic and straightforward. They accomplish this in drastically different ways. SPLs still rely on grease, providing it in a uniform and pre-selected way, intending to space out human interaction over longer periods.
Solid lubricant bearings are self-contained and have all the necessary elements to provide lubrication throughout a bearing’s entire lifespan. The interactions with these bearings are limited to installation and replacement.
Lubrication systems that move away from manual greasing are beneficial for bearing life, but some options offer more protection than others.
If you’ve read through this article, it stands to reason that you’ve been considering a move away from grease lubrication. Radical changes can initially seem daunting, but solid lubrication systems are successfully implemented across many industries and applications with great success. Moving away from grease creates a more efficient operation and reduces bearing failures, increasing production time.