Kaydon Corp. Bearings Division has added white papers, case studies, FAQs and more to the bearing remanufacturing section of its website, www.kaydonbearings.com.

"We've expanded the bearing remanufacturing content on our website to provide customers with more relevant, useful information," said Ron Shaw, Kaydon bearing remanufacturing manager. "Customers can learn more about bearing maintenance (especially for large diameter, lift-application bearings), warning signs of bearing wear or failure, and the remanufacturing process."

The website also includes a remanufacturing FAQ section, which provides answers to common bearing wear and repair questions.

The Kaydon bearing remanufacturing program returns bearings to service in the shortest possible time, on a cost-effective basis, while ensuring the highest quality workmanship. A bearing remanufactured by Kaydon performs as new and carries a warranty equal to a new bearing. Kaydon remanufactures bearings as small as 10" (25 cm) and as large as 240" (6.1 m) at a dedicated remanufacturing facility in Avon, Ohio.

Kaydon can remanufacture any ball bearing or roller bearing, including thrust, radial, cross roller, double row, three row, four point contact, eight point contact, cylindrical roller, and thin section bearings, regardless of the original manufacturer.

Kaydon offers free inspection of qualified slewing ring bearings up to 8' diameter in size. For more information, submit an RFQ from the remanufacturing section of KaydonBearings.com.

Kaydon infinite expertise in bearing design and manufacturing has established Kaydon as a leading slewing ring and thin section bearing remanufacturer in the world.
www.kaydonbearings.com

Bearings are critical components of machines and with proper performance monitoring, imminent failures can be identified and corrected. However, without a monitoring program in place, and subsequent corrective actions taken, a single bearing failure can result in full machine shutdown and countless hours of lost production.

Bearing monitoring is guided by three main senses: sight, sound and touch. Basic monitoring is conducted through elemental observations. However, many highly sensitive tools are available that amplify these observations so they are more noticeable, recordable, and include basic logic to assist with warning identification.

Visual Monitoring
Monitoring bearings visually through classical methods include observing lubricant condition, corrosion, and deterioration. Mounted bearings that are lubricated properly will purge grease from their seals. The condition of the grease upon purging can indicate improper relubrication intervals and/or contamination. Dark, cakey or milky grease are visual signs that relubrication intervals and procedures may be improved.

Evidence of corrosion is a valuable monitoring tool as well. High levels of corrosion can degrade material strength and performance. Deterioration of the surface, seals, or obvious physical dimensional characteristics should also warrant further investigation. These observations are often signals of wear, heat and other abnormal performance prior to total bearing failure.

Several monitoring tools commonly available to leverage visual observations include site gauges for oil lubricated bearings, and thermal imaging guns. Bearings that are lubricated by oil rather than grease are often fitted with site gauges, which will give an indication of the presence of oil and the quantity of oil available to the bearing. These gauges are practical and inexpensive.

Audible Monitoring
Traditionally, audible monitoring is one of the most common methods of monitoring machinery because odd noises are obvious indicators of improper operation, even to the untrained user. It is conducted quickly through an operator’s daily routines. After all, if a bearing within the machine doesn’t sound well it usually isn’t well.

The main problems with bystander audible observations is that (1) it usually identifies the later stages of bearing failure, when planning downtime for bearing replacement is impractical and (2) when audible feedback of a single bearing is masked by the overall noise of its environment. That’s when instruments such as stethoscopes (with amplification) and decibel level meters are advantageous. Both tools are available with a wide range of features that include quantified readings and recording features so bearing performance can be trended. These tools are also more useful at identifying improper operation at a less threatening stage of failure.

Bearings should run quiet and smooth; anything different will likely reflect a flaw or a problem with the bearing itself. Noises such as grinding or banging should be investigated quickly. These noises may indicate complete bearing failure and continued use may lead to catastrophic failure and/or damage to neighboring equipment. Bearing noises such as light clicking and squealing may indicate looseness, faults or skidding and should be inspected for cause and remedy.

Audible evaluation is not as sensitive as other monitoring techniques. It is primarily a method of identifying a failure more so than identifying poor performance. Additionally, audible monitoring in the early stages of failure is more noticeable at higher operating speeds than lower speeds.

Physical (Touch) Monitoring
Monitoring bearings by touch, and then trending the observations against historical performance is by far the most useful and accurate means for assessing bearing condition and predicting bearing failure. The touch method can be used to monitor temperature, vibration, and lubrication. 

Operating temperature is the most practical and beneficial monitoring method for bearings because expensive tools are not required and is appropriate to all types of applications; slow to high speeds, light to heavy loads. For example, the average threshold of pain for humans is approximately 130°F. If it is difficult to maintain hand-to-bearing contact for several seconds then the temperature is likely above 130°F. Furthermore, water droplets placed on a bearing housing that quickly boil will indicate that the bearing temperature will have easily exceeded 212°F.

There are also many useful tools available to measure and monitor bearing temperatures. The most common include thermocouples and resistance temperature detectors (RTDs), both of which can be permanently mounted to locations on the bearing housing for continuous real-time monitoring. Temperature switches are also available that can be utilized for warning and/or shutdown at dangerous operating temperatures. Many bearing manufacturers offer various permanently mounted sensors pre-installed in bearing housings in areas that will most accurately reflect the true bearing temperature, rather than the housing skin temperature.

Portable thermal imaging tools are also a quick and efficient means to monitor bearing performance. These tools use infrared thermography to visually identify variations in temperature over a broad area.  However, the most common portable temperature measurement tool is the infrared thermometer. Although it does not measure temperatures over a broad area, they are inexpensive and easy to use.

Monitoring and trending bearing temperature is important because as a bearing fails, the temperature will continually increase. Trending temperature over time will help identify a failing bearing in the early stages of failure.

Vibration analysis is the most information-rich method available for bearing analysis, and touch can help identify smooth versus rough operation. As safety permits, feel the housing during operation. Rough operation, jostling, or grinding may indicate a bearing problem.

You may also consider vibration measurement instruments to not only identify stages of bearing failure, but also identify overall machine performance and problems. Sensors mounted to the bearing may include permanently mounted or portable magnetic base accelerometers, displacement probes, or velocity pickups. Sensor selection is dependent upon the bearing speed, sensitivity requirements and the application. Although vibration feedback is highly beneficial, proper training is important due to the complexity in data collection and interpretation. 

Simple tests can also be conducted on purged grease to detect hard particle contaminants. Upon relubrication, rub some of the freshly purged grease between fingertips. Gritty grease may indicate a need to lubricate more often or wear from a failing bearing.

Many traditional and advanced options are available to monitor and evaluate bearing performance. Leveraging instrumentation to support traditional observations is a valuable practice in support of a predictive maintenance program.

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Galen Burdeshaw is Baldor’s customer order engineering manager for DODGE bearings and power transmission components. For more information, visit www.baldor.com.

Rolling bearings are high-precision machine elements whose service life directly determines the performance of machines. However, the actual service life is determined by many factors. Premature bearing failures cause costly equipment downtime, sometimes even with very serious consequences. Bearing experts provide some simple yet practical tips to optimize bearing performance.

Start with the right choice
Right from the very beginning, design engineers could enhance the bearing service life by selecting the right bearings for the application. Many factors — such as loads, rigidity, bearing life expectation, operating environment, etc. — need to be considered. Renowned bearing manufacturers have years of experience in different industrial applications. Developing bearing solutions with their assistance can contribute to optimal bearing and equipment service life.

Bearings from renowned manufacturers are produced with the latest technology and undergo stringent quality assurance procedures. Nevertheless, to guarantee the optimum bearing service life, special attention should be made in the following aspects: proper storage, careful mounting and dismounting, adequate lubrication and re-lubrication, appropriate condition monitoring, timely maintenance, and sound personnel training. 

Appropriate storage
In principal, all bearings should be stored in their original packaging until being mounted. They should be kept in a clean, non-humid environment at a fairly stable room temperature. Rolling bearings should be stored away from dust, water and aggressive chemicals. Vibrations and shocks could permanently damage the bearings mechanically and therefore must be avoided during handling and storage.

Basically all bearings must be stored flat. Particularly larger and thus heavier bearings might be deformed by their own weight if they are left standing vertically for a long period.

Special care should be taken for the storage of pre-greased (sealed or shielded) bearings. Such grease could change in consistence over a long storage period. This could raise the running noise to a certain extent when put in operation for the first time. Therefore the shelf life of such bearings should be controlled by an FIFO-system (First In First Out).
 
Cleanliness
Cleanliness is paramount when dealing with rolling bearings. The running surfaces and rolling elements usually have a surface finish roughness of tenths of microns (1/10 µm or 0.0001 mm). Such smooth surfaces are very sensitive to damages by contaminants. The lubrication layer between the running surfaces has usually a thickness between 0.2 to 1.0 µm. Impurities with particle size larger than the lubricants could get over rolled by the rolling elements and thus build up localized stresses in the bearing steel and eventually cause premature material fatigue. Normal environment dust has a grain size of up to 10 µm, which could already damage the bearings.

Therefore, a clean, dust-free environment is extremely important for bearing storage and mounting.

Thorough preparation for mounting
Bearings should be mounted and dismounted carefully by means of appropriate tools. Industry experts estimate that improper fitting causes 16 percent of all premature bearing failures.

For volume mounting in the production assembly the conditions are usually strictly controlled, and the suitable equipment is available for bearing installation. However, for maintenance or replacement work, the environments could vary. Therefore, thorough preparation for bearing fitting is necessary in order to ensure the optimum bearing service life. First of all, the relevant documentation, such as drawings, maintenance manuals, specifications, etc., should be carefully studied. All components, such as shafts, distance rings, housings, cups, flanges, etc., must be thoroughly cleaned and protected from contaminants. The conditions of such adjacent components should also be checked carefully.

Careful mounting and dismounting
Depending on the application, size and type of the bearing, an appropriate mounting method — mechanical, thermal or hydraulic — and tools should be selected. Here are some basic rules for bearing mounting:

Mounting forces should never be applied through rolling elements. This could easily lead to localized overloading in the contact area between the rolling elements and raceways which in turn causes premature bearing failures.

The bearing surfaces should never be hit directly with any hardened tools such as hammers, cotter pin drives, etc. This could cause a breakage or fragmenting of the bearing rings.

The instructions from the respective mounting equipment supplier should always be followed.

About 90 percent of rolling bearings are never removed from the equipment where they are built in. Usually only the larger bearings would be removed as part of the scheduled preventive maintenance programs. Same as mounting a bearing, dismounting should also be thoroughly prepared. During the dismounting, ensure the adjacent components such as the shaft or housing are not damaged. Appropriate methods and tools should be used for dismounting, depending on the bearing type, size and application.

Appropriate lubrication
The lubricant separates the metallic bearing surfaces such as rolling elements, rings, and cages and thereby reduces friction, preserves the metal parts and guards off contaminants and impurities. A wide range of lubricants — including grease, oil, and solid — is available for different operating conditions. The correct selection of lubricant is crucial to ensure optimal bearing and equipment service life.

Bearing lubricants undergo permanent mechanical stressing caused by the over-rolling of rolling elements. Moreover, lubricants change their chemical properties over time, particularly at high operating temperatures and in humid or polluted environments. All these lead to a gradual loss of lubricating quality.

Therefore bearings have to be re-lubricated at regular intervals to ensure maximum service life. The re-lubrication interval depends on operating conditions such as temperatures, running speeds, loads, environment, etc.

Only in case of pre-greased bearings (shielded or sealed bearings), i.e. “greased-for-life” bearings, the bearing service life is determined by the lubricant service life span.

Lubricants must be stored properly according to manufacturers’ instructions. Particular attention must be paid to keep the lubricant clean from any contamination. Prior to each application, the condition of the lubricant should be checked carefully.

Condition monitoring and maintenance
Generally rolling bearings are extremely reliable although they do not have an indefinite life. Like all other important components in the machinery, they should be inspected and maintained regularly. How often the inspections and maintenance should be carried out depends on the importance of the particular application and operating conditions of the individual equipment.

For bearing arrangements with critical functions, it is advisable to incorporate a condition monitoring feature at the design stage. Important parameters of the machine operation such as vibration and noise can be monitored continuously. Preventive measures could be planned before breakdowns.

Training
Practice makes perfect. But proper training provides the basis for the practice. Reputable bearing manufacturers offer various training programs for commercial, technical and workshop staff. Costly human errors can be avoided if maintenance technicians possess fundamental knowledge in handling bearings. Design and product development engineers can maximize the equipment performance and minimize life-cycle costs by optimal design of bearing locations.

Bearings are often critical components in all machines. Proper storage, careful mounting and dismounting, adequate lubrication and re-lubrication, appropriate condition monitoring, timely maintenance and, last but not least, sound personnel training are essential to improve bearing service life, and therefore enhance equipment performance.

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This is an edited article provided by NKE, which is distributed in Canada through Global Bear Inc. For more information, visit www.globalbear.ca.

The Timken Company has announced an average increase of 10 percent in calculated load ratings for Timken  tapered roller bearings used in a wide variety of mobile and industrial equipment.  With advanced technology engineered into the bearings, performance assessments warrant this increase in predicted life across 20 product types used in industries such as rail and vehicle systems, mining and aggregate, agriculture and food processing, and energy generation from wind, coal, oil and gas.

Based on extensive lifecycle testing, Timken's higher performance ratings translate into greater value, with longer predicted useful bearing life and heavier load-carrying capacity than previously published. 

"As the tapered roller bearing technology leader, Timken continually enhances this core product line," said Douglas H. Smith, Timken senior vice president of technology and quality.  "Companywide, our engineers and manufacturing teams demonstrate unwavering commitment to build upon our legacy of innovation and continuous improvement. The cumulative impact of improvements in Timken steel-making technology, fundamental design, and precision manufacturing and gauging has measurably increased the durability of Timken bearings."
www.timken.com

For professionals dealing with highly specialised mechanical components like rolling bearings, a general technical understanding of the products can help them improve productivity and cut costs. Unfortunately, the “formal education” at technical schools hardly covers the practical skills needed for the industry. To fill this void, many leading bearing manufacturers offer specialised training courses.

Generally, any company dealing with bearings benefits from such training programs — optimised efficiency at workplace and motivated employees are just two of the direct results of appropriate training.

For machinery manufacturers, design and product development engineers can maximise equipment performance and minimize the life-cycle costs by optimal design of bearing locations. In one case, after acquiring adequate knowledge, a product design engineer could save 50 percent costs on one bearing location without sacrificing performance.

Equipment end-users can profit from bearing training too. According to experts, human errors are a major cause of equipment failures. Correct handling of bearings — such as storage, lubrication, and mounting/dismounting — not only ensures less bearing damage and longer bearing service life, but also results in lower maintenance costs, improved safety and more equipment uptime.

Not only engineers and technicians benefit from bearing knowledge. Commercial personnel such as sales and purchasing professionals can improve their job performance through bearing training. For example, a buyer can reduce costs by choosing a technically equivalent product variant for the application, or sourcing bearings from an alternative supplier with equal quality.

How to choose bearing training
First of all, the training needs and goals of a company should be identified. It has to be determined who should be trained in which fields. Next, the training has to be incorporated into the staff-training plan. The following factors should be considered when choosing a bearing training program:

• Reliable training provider: Reputable bearing manufacturers, such as NKE, offer well-organised training seminars to business partners.
• Curriculum design: Ask the training provider for a curriculum outline. You should find out whether the courses are targeted to your employees (commercial, technical or workshop personnel), as well as the breadth, depth and structure of the courses. If the standard modules do not completely suit your needs, ask for customised courses.
• Instruction methods: Usually bearing training is conducted in small classroom groups (maximum 10 to 15 people) for a dedicated learning environment and individual attention. Visual aids and handout notes should be provided. For practical topics such as bearing handling, hands-on exercises should be included.
• Instructors: The instructors should possess a combination of solid theoretical foundation and practical experience in bearing applications. They should be competent in knowledge sharing and training.

Learning does not stop when training is over. What has been taught in the classroom must be practised in the real world. Depending on programs, the trainees should show improved performance within days to months after the training. The post-training evaluation should be taken into consideration when planning for the next programs.

Training is an investment in productivity. It equips technical and commercial professionals with the essential knowledge to enhance their job performance. For the company, it means optimized product development, reduced procurement and maintenance costs, increased facility uptime, enhanced safety, employee loyalty and customer satisfaction. All these contribute to the long-term success of a business.

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This is an edited article provided by NKE. In Canada, NKE products are distributed through Global Bear Inc.

The Bearing Specialists Association (BSA) is promoting a pair of valuable education tools that can help end users maximize their bearing investment. Bearing Installation – Fitting Practice (PDF) and Bearing Mounting Tools (PDF) offer essential installation information for the distributor, manufacturer and the end-user in an easily-downloadable PDF format from the BSA website.

Bearing Installation – Fitting Practice details the steps in achieving proper radial retention of bearing rings on their respective seats. The proper selection of shaft and housing bore dimensions and tolerances prevents rings from rotating on their seating surfaces and prevents unnecessary abrasion, making it an essential step in getting the maximum life from every installation.

The brief also explains the International Standards Organization (ISO) coding system and its established standards for machining quality and degree of interference/clearance between ring and seat. This standard allows manufacturers worldwide to clearly communicate fitting practice.

In addition, Bearing Installation – Fitting Practice explains and illustrates three different fitting conditions, and concludes with an illustrated appendix that compares bearing retention rules and recommended fits.

Bearing Mounting Tools focuses on the importance of proper handling practices before and during bearing installation to avoid damage that will impact performance. It covers the use and limits of tools such as a bearing heater, spanner wrench and dead blow hammer.

BSA is regularly highlighting the single-topic publications of technical information designed by BSA distributor members and participating manufacturers to deliver expertise designed to meet the needs of the end user as well as bearing industry professionals. Over the past several years, the association's Educational Services Committee has published 25 Bearing Briefs, all of them available as free, downloadable PDFs from the BSA website, www.bsahome.org.

Mill Log Marine in Burnaby, B.C., has been appointed the authorized distributor in British Columbia for Canadian manufacturer Thordon Bearings, replacing W.L. Marine. With this agreement, Mill Log Marine becomes the stocking distributor for the manufacturer of non-metallic oil and grease-free bearing systems.

“Mill Log Marine’s reputation, expertise and knowledge of the marine market gives us great confidence in knowing that our products will be strongly supported in western Canada”, added Jan Willem de Jong, commercial director of Thordon Bearings. “By partnering with Mill Log Marine, we can now offer our British Columbia customers an outstanding level of service while offering the highest quality and most environmentally friendly bearing solutions in the marine, clean power generation and industrial markets.”

Don Lindsey, director of sales and marketing for Mill Log Marine, stated: “Thordon Bearings Inc. produces high quality, water lubricated rudder and propeller shaft bearings specifically for the workboat and commercial vessel market. … With working applications in extreme operating conditions being used by the U.S. and Canadian navies, cruise ships, bulk carriers, tankers and workboat ship owners across the globe, we are excited to bring these bearings to this region.

“Furthermore, this product eliminates the need for petroleum-based products for lubrication, which helps the environment and increases the life of the bearing.”

Thordon Bearings designs and manufactures a complete range of polymer bearing and shaftline products for the marine, clean power generation, pump, offshore and industrial markets. Products are sold through an extensive factory trained distribution network that has been established in over 70 countries to service the international customer base.
www.milllog.com
www.thordonbearings.com

The Education Services Committee of the Bearing Specialists Association (BSA) has selected The Best Kept Secret in "Green" Technology as the next topic in their series of Bearing Briefs.

The Best Kept Secret in "Green" Technology details the many ways in which bearings contribute to a greener planet.

The brief point outs the bearing industry is constantly developing new bearings that operate at higher speeds, generate less friction (and therefore less energy consumption), support heavier loads, last longer, use environmentally friendly lubricants, and cost less throughout their service life. In short, the bearing industry is making the most out of existing machines while reducing their impact on the environment. Equally important, the bearing industry also helps users and engineers balance bearing features to achieve optimum machine performance.

Over the last several years, BSA's Educational Services Committee has published twenty-five Bearing Briefs, all of them available as free, downloadable PDFs from the BSA website at www.bsahome.org.

As an addition to EC motors, Maxon Motor launches its EC 25 High Speed-a speed-optimized and small-sized 250 W drive. The EC 25 High Speed has a rotor equipped with preloaded ball bearings and a two-pole Neodymium permanent magnet. In conjunction with low-loss in high speed winding, the optimized magnetic return and dynamic balancing is said to make the motor a “real power pack in a class of its own.”

When it comes to mounted bearing installation and maintenance, there are many industry myths and misconceptions that may affect plant uptime and overall performance. Maintenance managers need to be aware of these elements, so that they can maximize performance and keep the plant running.

Bearings can fail for many reasons and studies have helped to understand the reasons for these failures. As shown in the pie chart (click it to expand it), a large majority of bearing failures are related to lubrication problems and contamination. The following myths and misconceptions address some of these issues, and provide insight into how they can be resolved and avoided.

Installation Myths • #1: Using a hammer is okay to position a bearing • #2: Off-the-shelf TGP shafting is always the best option • #3: It's okay to hand-tighten setscrews, one at a time Lubrication Myths • #1: Re-lubrication once a year is sufficient • #2: Always add grease until grease purges from the seal • #3: If there is noise, it must be the bearing and grease should be added • #4: Any grease will do • #5: Simply shoot grease through the grease fitting Misapplication Myths • #1: Bearings will not be hot to the touch • #2: Bigger bearings are always better • #3: Sealed/lubed-for-life bearings will last forever

Installation Myth #1:
Using a hammer is okay to position a bearing right?
FALSE: Never deliver a direct blow to a bearing. The rolling elements and raceway are hardened, but they can still be damaged. Impact from the hammer can transfer to the raceway leaving permanent indentations, and running the bearing with these indentations can cause noise and dramatically reduce bearing life. You should check the shaft diameter, look for burrs, dirt or corrosion on the shaft and if needed use a press to slide the bearing on. If a press is used, pressure should be placed equally on the face of the inner ring to help avoid damage to the raceways and rolling elements.

Installation Myth #2:
Off-the-shelf TGP shafting is always the best option.
FALSE: TGP is turned, ground and polished. It's a manufacturing method, not a tolerance range or a guarantee that the shaft meets the bearing manufacturer's specified range for diameter and roundness. It's recommended to measure and specify the proper shaft diameter and review the bearing manufacture recommendations.

Installation Myth #3:
It's okay to hand-tighten setscrews, one at a time.
FALSE: Setscrews are an integral part of the locking system between a shaft and bearing, and should be tightened to the manufacturer's recommend torque. Under tightening may result in loss of lock and slipping of the bearing on the shaft, and over tightening may result in raceway distortion or inner ring cracking. The recommended approach is a half-full/full method. Half-full/full refers to tightening the first setscrew to half the recommended torque, the second setscrew to the full torque then back to the first setscrew for the full torque.

Lubrication Myth #1:
Re-lubrication once a year is sufficient.
FALSE: Re-lubrication is necessary to replenish grease in the bearing when the current grease breaks down or deteriorates. Re-lubrication is a necessity because the base oil breaks down as a result of temperature. The lubrication film between the bearing rolling element and the raceway can diminish or is eliminated, resulting in metal-to-metal contact. Re-lubricating the bearing replenishes the oil, helping maintain the proper lubrication film.
Pumping new grease into the bearing also helps flush away contamination. Many mounted bearings are designed to allow the grease to enter the bearing cavity as close to the rolling elements as possible. As more and more grease is added to the bearing, the old grease is pushed out of the seals (if the seals are purgeable). The action of purging grease pushes and helps keeps dirt away from the seals.

Bearing manufacturers offer general re-lubrication recommendations, including amounts and intervals, as suggested starting points. The amount of grease used at re-lubrication can vary with bearing size and type. Re-lubrication intervals can vary based on load, speed temperature, or environmental conditions. For example, a mounted ball bearing in lightly loaded, low-speed, clean environments may only need re-lubrication every 12 to 24 months.

However, each application is different and applications with higher speeds, temperatures, or heavy contamination would require more frequent bearing re-lubrication, possibly daily to once a week. Review of the bearing manufacturer's recommendations is encouraged. Specific applications should be monitored regularly and lubrication intervals and amounts adjusted accordingly.

Lubrication Myth #2:
Always add grease until grease purges from the seal.
FALSE: If you pump grease into the bearing until it purges out the seal, you likely have completely filled the bearing cavity. If you completely fill the bearing with grease, the excess grease can increase bearing operating temperature and potentially create enough pressure to blow the seal out.  However, in a dirty and/or low-speed application where contamination may easily enter the seals, filling a bearing full of grease may help improve bearing performance. Application experience will dictate when the entire bearing cavity should be filled with grease.

Lubrication Myth #3:
If there is noise, it must be the bearing and grease should be added.
FALSE: If the bearing is making noise, internal damage has likely occurred. If the bearing continues to run without being replaced, more internal damage may occur to the bearing, with the potential for catastrophic failure. Adding grease may provide temporary relief, but a noisy bearing should be closely monitored and replaced as quickly as possible. The root of the failure should also be investigated either with independent or manufacturer failure analysis (manufacturer analysis requires removal of the bearing as soon as possible to aid in a more accurate diagnosis of the problem).

Lubrication Myth #4:
Any grease will do.
FALSE: Not all types of grease are the same. Some grease can be incompatible because of the different thickeners (soaps) used. When two incompatible greases are mixed, they may thicken and harden or become thin and leak out of the bearing. For example, many electric motors use a polyurea thickener and some mounted ball bearings use lithium-complex thickeners. This grease is borderline compatible, and depending upon the final make up, may or may not work together. Grease types can also be incompatible based on the viscosity or type of the oil in the grease, so consulting with a lubrication supplier is always recommended.

Lubrication Myth #5:
Simply shoot grease through the grease fitting.
FALSE: Before putting grease into a system, it's recommended to fully wipe the grease fitting and ensure that the grease gun is clean. One good practice is to put the grease gun tip in an oil bath or wrap it with a plastic cover to protect it.

Misapplication Myth #1:
Bearings will not be hot to the touch.
FALSE: Normal bearing operating temperatures can range from 80 degrees to 150 degrees Fahrenheit, but certain applications may run higher or lower than others. Most bearings are rated for -20 degrees to 220 degrees Fahrenheit, but can be supplied with special grease, seals or heat stabilizing processes that allow them to operate at higher temperatures.

Bearings typically run hotter at start up or right after re-lubrication because excess grease increases drag and friction in the bearing. The bearing will typically reach steady state operating conditions, as excess grease is pushed out by the rolling elements and purged from the seals. Spikes of up to 50 degrees Fahrenheit at start up and a spike of 30 degrees Fahrenheit can occur after re-lubrication.

Misapplication Myth #2:
Bigger bearings are always better.
FALSE: Bigger bearings have a higher load capacity, which may show a higher bearing fatigue life. If the load isn't high enough to achieve the minimum load requirement, however, the rolling elements can skid along the raceway instead of roll. Skidding along the raceway may result in high operating temperatures, excessive wear, lubrication breakdown and subsequent bearing failures.

Misapplication Myth #3:
Sealed/lubed-for-life bearings will last forever.
FALSE: The bearing life will depend on the grease life, which is affected by operating conditions (speed and load) and environment (temperature and contamination). Various things can be done to improve grease life, such as enhanced seals, proper installation practices and proper grease selection. Ultimately, the best bearing is the properly lubricated bearing.

If you have a bearing that doesn't achieve the desired bearing operational life, consult a bearing manufacture that can assist in properly selecting the bearing for the application.

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This feature was previously published in REM magazine. Ian A. Rubin is marketing manager, mounted bearings for Sealmaster and Browning-branded products at Emerson Power Transmission Solutions. For information, visit www.emerson-ept.com.