Avoid These 3 Mistakes When Lubricating Bearings

Friction is all around us. Without it we would find it very difficult to run, walk, or eve stand on our own two feet. We need friction to drive our cards and fly our airplanes; and we need friction for our motors to drive pumps. But when it comes to our plant machinery, friction is both friend and foe. If part of your job is greasing plant machinery, then you know well the battle against frictional forces that threatens the useful life of rolling element bearings

Lubrication of rolling element bearing is one of the most misunderstood and abused tasks in industry. Can it be true that 40% of bearings never live to their engineered life cycle and that bad lubrication practices are the leading cause of this mortality? Bearings depend on grease to reduce friction levels. By avoiding three common mistakes when greasing bearings, you can predict the right time to grease, know how much grease to apply, and be confident in the bearing’s overall health.

Mistake No.1 – Lubricating based on TIME instead of CONDITION

Lubricating a bearing once per week or once per month may seem like a sensible thing to do. After all, performing scheduled maintenance at regular periods is an age-old concept.

Bearings need grease for one reason only; to reduce friction. As long as the lubricant is performing that service well, there should be no need to change it, or add more.

Yet we frequently do, with catastrophic results.

Lubricating a bearing just because your calendar told you “time is up!” is the first mistake. Monitor, measure and trend friction levels with ultrasound to know when it is the right time to grease.

Mistake No.2 – Over and under lubrication

 The second mistake we must avoid is adding too much, or not enough grease. Too much grease builds pressure, pushing the rolling elements through the fluid film and against the outer race. The bearing now has to work much harder to push the rolling elements through a mud bog of grease.

The increased friction and pressure from too much grease raises the temperature inside the bearing. Excess heat could decrease the effectiveness of the lubricant causing the oil to separate from the thickener. Not adding enough grease has the same life-shortening effect.

How do we know when just the right amount of grease has been added? By monitoring the friction level with ultrasound as new grease is applied… slowly, one shot at a time. Listen to the bearing and measure the drop in friction as the grease flows in to the bearing. As the decibel level approaches a minimum value and stabilizes pay close attention. Add single shots. Should the decibel level begin to increase slightly, stop! The job is done.

Mistake No.3 – Using a “Listen-Only” ultrasound instrument

 Like any job there is a right way and a wrong way to do things. Simply listening to a bearing with an ultrasound device that gives no measurement feedback is a recipe for disaster. The audible feedback alone is too subjective to draw any comparative conclusions. No two people hear the same and there is no way to remember what the bearing sounded like a month ago.

The third mistake is depending solely on subjective ultrasound noise when precise quantifiable data is available. Therefore, always use an ultrasound instrument with digital decibel metering. Better still, use a device that provides multiple condition indicators. Max RMS and Peak dB measurements indicate alarm levels and greasing intervals while Ultrasonic Crest Factor provide insight about the bearing condition in relation to its lubricant. Crest factor helps us differentiate between bearings that need grease and bearings that need to be replaced.

Clear benefits of avoiding the three mistakes

Ultrasound assisted lubrication of plant assets offers significant benefits that calendar-based lubrication cannot. Lubrication serves a primary purpose, which is to create a thin layer of lubricant between rolling and sliding elements that reduces friction. So it makes sense that the best way to determine the lubrication requirement of a machine is to monitor friction levels; not time in service.

Optimizing lubrication of plant machinery with ultrasound will result in a significant reduction in grease consumption. Having an ultrasound program in place will help create a better culture involving cleaner storage practices, sampling, and avoiding mixing greases.

Machines that are properly lubricated require less energy to run. Imagine that reducing the amount of money spent on grease will actually lead to lower energy bills. Machines that consume less electricity run cooler and machines that run cooler have longer life cycles.

Ok, the real reason to optimize bearing lubrication is to extend the life of bearings by making sure they have the right amount of grease, but not too much. When everything is running according to plan lube-techs will spend less time greasing bearings that do not need it. So when counting up the benefits of your ultrasounds program do not forget to add “decreased labor” to the long list.

Finally, by monitoring the condition of your machinery’s lubrication, you are at the same time collecting valuable condition data about the machine itself. Dynamic and static ultrasound data coupled with condition indicators such as Overall RMS, Max RMS, Peak, and Crest Factor are all indicators of bearing health. A practice that does not use this SDT combination is not a real solution when lubricating bearings. Who knew so much good could come from such a simple shift from calendar to condition based maintenance? Now you know.

Darbar Company is Pakistan's leading supplier of Bearings, Timing Belts, and Roller Chains. Our bearings are of the highest quality and require little maintenance. We can guarantee you that our bearings will perform far better than any other on the market, and our prices are very competitive as well. 

Original article extracted from Bearing-News magazine

Three more bearing killers and how to stop them: Part 2

Bearing failure can grind your operations to a halt, resulting in significant lost time and production. Here are the last three of our six common factors that can cause bearings to fail, and what you can do to prevent them.

#4: Contamination. Even the tiniest of foreign particles can interfere with the lubrication that enables a bearing to function as intended. There are a number of contamination sources, depending on the application. Shop dust, sand, fine metal particles from nearby machining, water and dirt can all interfere with the lubricant that keeps a bearing operating, and can damage the bearing itself. Particles rolling through the bearings and rolling elements will cause premature damage, increasing stress and shortening overall bearing life.

The best protection against contamination is a proper seal, which must be matched with the given application to offer the best possible performance. This information should be available through the bearing manufacturer. Generally, seals should be regularly checked for hardening and cracking around the radial lip; they should be replaced as soon as possible if any visible damage is detected.

Contamination can occur at other points in the bearing lifecycle. Technicians should routinely test oil and grease samples for solid particles. Additionally, when bearings are removed for inspection, technicians should make sure to wash, dry and then coat bearings with the appropriate preservative before packing away, using the proper storage techniques.

#5: Overloading. Bearings are designed and engineered to operate at specified loads, and when pushed beyond those limits, trouble can occur. Overloaded bearings can fracture components, and left unchecked can lead to more serious damage or consequences.

Like overheating, warning signs of overloaded bearings should be monitored constantly. Abnormal noises and vibrations, overheating, the presence of metallic chips in lubricant filters, and overall diminished performance of the bearing can all indicate that a bearing is operating beyond its load limits. The higher the overload, the greater the damage. Other indications include the fatigue, pitting or flaking away of bearing materials, roller fracture, peeling, and potential plastic deformation or subsurface fracture of the rolling elements or raceways.

#6: Corrosion. Bearing applications in harsher industrial environments are more susceptible to corrosive damage caused by rogue fluids or corrosive atmospheres that can interfere with the protective lubricant. Corrosion can lead to wear, which can, in turn, lead to bearing failure

Like overloading, subpar performance due to corrosion can often be detected by increased vibration and noise during operation. Corrosion can be identified by reddish and brown discoloration found on the bearings and raceways—not to be confused with the discoloration caused by overheating. Ensuring the use of proper seals and that those seals are not damaged, is one of the best ways to prevent corrosion on the bearing and raceways. External seals can also be used in more extreme environments if necessary.

Thorough documentation of your bearing installation and maintenance processes can help ensure technicians are being diligent in their monitoring of these common causes of bearing failure. Recordkeeping can help identify trends in bearing performance, forecasted maintenance, and the length of service intervals. Include date, equipment model and serial numbers, bearing assembly and serial number, and the bearing’s manufacturer in your documentation.

In many cases, bearing damage can progress over time. Periodic or continuous condition monitoring (vibration, temperature, lubricant sampling, etc.) can aid equipment and process operators define trends over a bearing lifecycle. Establishing specific operating limits can help define the most appropriate interval for bearing replacement.

Armed with this information, more informed decisions can be made to ensure operations keep your business running smoothly, efficiently and profitably.

Darbar Company is Pakistan's leading wholesale distributor in Power Transmission products. Darbr Company carries over a million types of bearing ranging from Needle, Ball and etc. You can send your specific inquiries by filling out this form

Check out the other three reasons here

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3 Bearing Killers and How To Stop Them: Part 1

Bearing failure can grind your operations to a halt, resulting in significant lost time and production. Here are the first three of six common factors that can cause bearings to fail, and what you can do to prevent them.

No matter the application, the proper functionality of bearings is essential to optimize operations. Whether a bearing is a cylindrical, spherical, ball or roller bearing, its precise design and engineering require special attention to ensure it’s working correctly. Bearing failure means downtime, maintenance and a major blow to operational efficiency—and in many cases, that failure can be easily prevented.

Applications requiring dependable bearing operation are countless but common reasons for bearing failure are fairly narrow. Though improvements in technology, design and user training have helped reduce failure incidents, understanding how and why bearings commonly fail is critical.

Here are the first three of six common reasons for bearing failure and how to make sure they don’t bring operations to a halt:

#1: Improper Handling and Installation. Proper bearing care begins when the bearing first arrives at the application site. From the shipping dock, to storage, to installation, proper handling and care is necessary to ensure the bearing will function as intended.

Even the smallest imperfections can shorten a bearing’s lifespan, and many nicks and scratches occur before the bearing is even put into use. Damage can occur when a bearing is in storage; therefore, if stocking bearings prior to needing them on your plant or shop floor, make sure the proper storage techniques are being followed. Don’t remove the bearing from the manufacturer’s original packaging unless absolutely necessary; if it must be removed, store in anticorrosive wrapping, and apply the appropriate preservatives to the bearing first.

When ready to install, cleanliness is critical. Technicians should perform the work in as clean an environment as possible, using clean tools, and should take care not to remove any of the preservative coating. Carelessness is the most common cause of damage to the bearing throughout the installation process. Poor handling while removing the outer races from housings or wheel hubs, for instance, can leave burrs or high spots in outer race seats. Tools can inadvertently gouge housing seats, leaving imperfections that can increase rolling contact stress, limit fatigue life or fracture machine components in the worst cases—all the more reason to ensure your installation processes are conducted with care and precision.

#2: Improper Lubrication. Lubrication is the lifeblood of proper bearing operation, and it is dependent on several variables in any given application.

Most bearing manufacturers and suppliers will recommend a specific lubricant type, grade, supply system, viscosity and additives for the application. They will also provide the amounts of lubricant that should be used and how often it should be changed or replenished. More application-specific recommendations and details including loading, speeds and sealing are often included as well.

Just like the bearings themselves, lubricants must be stored properly. Shelf life, temperature, filtration and other precautions will again be available via your bearing/lubricant supplier.

Technicians should adhere closely to these recommendations—bearing compatibility and performance depend on it. Underfilling and overfilling, mixing and matching lubricants, and changing lubrication at irregular intervals can all result in significant damage that can bring your operations to a standstill.

#3: Overheating. A primary function of proper lubrication is to prevent the overheating of bearings and associated components. Overheating can lead to damage and ultimately breakdown for a variety of reasons related to the lubricant. Higher temperatures can be caused by ambient temperatures, process temperatures, and severe operating conditions that can increase rolling contact friction. Likewise, lower ambient temperatures can have a negative effect—lubricant viscosity increases at lower temperatures and can cause improper flow and therefore compromise protective benefits. Your lubricant supplier can provide the ideal operating temperature change.

Technicians can and should do more than simply follow supplier instructions to ensure lubricants are performing properly and keeping their bearings at the appropriate temperatures. Be vigilant about monitoring bearings for heat-related trouble signs that can impact lubrication and ultimately the bearing itself. In order of severity, these symptoms include:

• Bearing discoloration. This will occur as a result of metal-to-metal contact, a sure sign of a lubrication issue. Look for gold and blue discoloration on races and rollers; lubricant staining is common in mild cases, while the metal itself may be discolored by excessive heat in worse cases.
• Peeling and scoring. Marks cut into the metal or peeling metal indicate a more severe lubrication/heat issue and should be addressed immediately.
• Localized scoring. This occurs due to the breakdown of the lubricating film which causes direct contact between components. Address immediately.
• Cumulative wear. High localized heat can alter the geometry of the bearing itself, resulting in a locked-up bearing that can cause significant additional damage.

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Bearing Maintenance From Start to Finish (Part 3)

For any type of bearing in rotating machinery, applying best maintenance practices and using the correct enabling tools can help contribute to maximum bearing service life.

Bearings should always be properly stored, mounted, adequately lubricated when and where required, monitored, dismounted, and ultimately inspected to uncover root causes of any damage.

While particular applications will present unique factors influencing a bearing’s service life, the following maintenance-oriented guideline can substantially improve the life of bearing.

Turning to bearings in service

In service, sufficient lubrication is essential. Maintenance goals: Deliver the right lubricant in the right amount at the right time.

Among lubricant delivery methods, manual lubrication (with grease gun) typically can present major challenges for maintenance technicians if the appropriate tools, practices, and knowledge are absent – and reliability can further be affected by under- or over-greasing. As a practical alternative, automatic lubrication can be employed to provide quantities of clean lubricant on a regular basis, while increasing safety and saving time for staff. Ready-to-use or tailored systems can be engaged, depending on application, lubricating points, and similar considerations.

Over time, the lubricant in a bearing arrangement gradually will lose its lubricating properties due to mechanical work, aging, and/or the buildup of contamination. This underscores a maintenance-related necessity for grease to be replenished or renewed and for oil to be filtered and changed at regular intervals to help promote maximum bearing service life.

To gain long bearing life it is imperative to determine the condition of machinery and bearings while in operation. This can be accomplished with a process known as “condition monitoring.”

Condition monitoring allows for the repair of components detected as problematic prior to their failure. This is accomplished by performing condition-based maintenance. The approach not only reduces the possibility of catastrophic failure, but also allows plant personnel to order parts in advance, schedule manpower, and plan unrelated repairs during the downtime.

The most significant machine-condition parameters to help monitor the health of a bearing include (in no specific order) noise, temperature, speed, vibration, and alignment. A variety of measuring instruments will enable users to analyze all factors.

When a bearing must be taken out of service, for whatever reason, proper dismounting practices should be followed.

One reason for dismounting an old bearing is to replace it with a new one. When proceeding, care must be taken not to damage the shaft in the process, which can result in compromising a machine's efficiency. A damaged shaft can greatly influence the service life of the new bearing.

Another reason to dismount bearings is for maintenance or replacement of other machine components. Since these dismounted bearings will be mounted again (unless they are damaged during dismounting), proper dismounting methods and tools should be enlisted. Choice of tools will depend on bearing type, size, and fit.

In situations where a bearing must be replaced due to premature failure, detective work focusing on bearing and grease analysis can help point to root causes. Among common root causes: inadequate lubrication, contamination, errors in mounting/dismounting, and/or electrical damage. Pinpointing the actual cause(s) will help prevent a repeat of history.

When it comes to bearing maintenance, every decision and practice can impact a bearing’s performance, reliability, economy, and service life. Partnering with an experienced bearing manufacturer can open the door to the knowledge and technologies that will support maximized bearing life and reduced maintenance time, labor, and costs.