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

Read the original article at BearingTips: http://bit.ly/2lIiyHR

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.

Bearing Maintenance From Start to Finish (Part 2)

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.

Mounting and Greasing

Because they are precision components, bearings should be handled and mounted with care using correct techniques and technologies. An estimated 16% of all premature bearing failures are caused by poor fitting, usually using brute force, and being unaware of the availability of the suitable mounting tools and methods.

The primary methods for proper mounting of a bearing are commonly referenced as “cold” or “hot,” consistent with their enabling technologies. Cold mounting, or mechanical mounting, generally is recommended for small and medium sized bearings (with outside diameters up to 4 inches); methods involving heat mounting will be appropriate for relatively larger bearings; and hydraulic techniques should be considered when mounting especially large bearings. Tools have been developed to accommodate each particular method.

In cold mounting, the misguided practice of using a standard hammer and pipe for the job has long been discredited due to the damage that can occur. This practice can cause debris to enter the bearing or, if not done properly, a pipe can slip and impact the internals of the bearing. Best practice: The use of fitting tools to eliminate harmful brute force and apply the proper force to both bearing rings to isolate the rolling elements from impact force for a more reliable installation.

Hot mounting, where the bearing is pre-heated, provides a practical solution to allow for a bearing’s expansion and subsequently easier installation, while maintaining specified interference fit after the job is completed.  Induction heaters can integrate various features to help prevent bearing damage during the heating process. These solutions stand in direct contrast to less effective (and potentially dangerous) methods, including an open flame, hot oil baths, and ovens or hot plates.

For the larger sized bearings, hydraulic techniques and compatible tools and equipment deliver the goods. Hydraulic techniques allow for more control and further help to maintain precision, accuracy, and repeatability; minimize the risk of damage to bearings and shafts; require less manual effort; and promote greater operator safety.

Choosing the proper bearing lubricant will help bearings perform as long as intended. Good lubricants primarily provide a separating film between a bearing’s rolling elements, raceways, and cages to prevent metal-to-metal contact and undesired friction that otherwise would generate excessive heat that could lead to adhesive wear and subsequent metal fatigue and spalling of the bearing contact surfaces. The proper lubrication further acts to inhibit wear and corrosion and helps guard against contamination damage.

Half of all bearing failures attributed to poor lubrication are caused by selection of an inadequate grease type for the operating conditions or to mixing incompatible greases with different properties. Therefore, it is imperative for optimized bearing performance that the correct type of grease be selected to deliver the necessary base oil viscosity in the proper amount at the prevailing operating temperature.

Grease has traditionally served as the preferred lubricant for rolling bearings. The practical benefits become apparent: Grease is easy to apply, can be retained within a bearing’s housing, and offers protective sealing capabilities.

Greases are classified by their stiffness or consistency according to the U.S. National Lubricating Grease Institute (NLGI) and are graded from NLGI Class 000 (very soft) to 6 (very stiff). These classifications are based on the degree of penetration achieved when a standard cone is allowed to sink into the grease at a temperature of 25°C for a period of five seconds.

Grease composition is roughly 85% base oil (mineral or synthetic) and 15% soap or thickener and will vary from grease to grease. The base oil is the oil inside the grease, which provides the lubrication under the operating conditions. The soaps or thickeners hold the oil and/or additives together to enable the lubricating grease to function and, in some cases, may enhance the lubricant film. (The type of thickener gives the grease its typical characteristics, retaining the oil in a similar manner to a sponge retaining water.)  Additives provide additional characteristics such as wear/corrosion protection and friction-reducing effects.

By varying oil viscosities, soap, and additives users can benefit from greases with distinct characteristics able to suit particular applications and operating conditions.

Bearing Maintenance From Start to Finish (Part 1)

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.

Making the initial right moves

From the outset, proper storage is critical.  Bearings should always be stored in a cool, clean, low-humidity environment free of dust, shocks, and vibrations.  (For these reasons, storing bearings directly on a floor should be avoided.)  They should ideally be stored flat rather than on end and be kept in their original, unopened packages until just before mounting.  If kept in a standing position, the likelihood of false brinelling (wear of the raceways and rolling elements caused by residual vibration) increases significantly.  False brinelling is much less likely to occur in bearings laying flat.

In the cases of sealed or shielded types of bearings, operators should be cautious when storing them over long periods of time. The lubricating properties of the grease used to fill these types of bearings may deteriorate, causing potential lubricant-related problems when a system is up and running.  (Most bearing manufacturers have specific shelf-life limits, based upon the greases used in their bearings.)

The importance of cleanliness cannot be over-emphasized. All bearings should be kept clean, because contamination and corrosion will shorten the life of any bearing.

When a bearing is ready to be mounted, maintenance staff should confirm that shaft and housing are clean, undamaged, and dimensionally accurate (with proper fit and tolerance); lubricant is clean and correctly specified; necessary tools and equipment are on hand, and safety precautions are in place.