Articles About Bearing Predictability
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How SKF's R&D department is solving the mysteries of bearing performance.
The average travel time to work in the United States is 25.4 minutes, according to the U.S. Census Bureau. This number is probably low if you factor in a traffic accident in New York City, light rain in Chicago or it's simply Tuesday in Los Angeles. It's safe to say 25.4 turns into 45 minutes in many areas of the country at seven o'clock in the morning.
A Chicago-area bakery was replacing the tray support bearings in its ovens on a reactionary basis. Their weekly inspection cycle was resulting in two mechanics spending an average of 20 labor hours per week to replace failed bearings. The premature bearing failures were caused by a combination of the high heat and humidity in the ovens, resulting in lubrication failure and contamination. When BDI was asked to recommend a solution, the bakery was averaging one month of bearing life in this application.
Mechanical guiding systems, such as crossedroller bearings, work well for most motion control applications; however, when precision, angular repeatability, and geometric performance (runout, straightness) are critical or where submicron bearing rumble is problematic, air bearings are recommended. An air-bearing stage is a rotary or linear positioner that floats on a cushion of air, using one of several preload mechanisms, nearly eliminating mechanical contact and thus wear, friction, and hysteresis effects. Here are eight reasons why an air-bearing stage might be the right choice for your application:
Latest News from around the industry.
Equipment downtime and reduced component life are a few of the consequences â” and potential costs â” of using the wrong seals on many types of industrial equipment including pump bearing frames, electric motors, fans, pillow blocks, gearboxes and more. However, if correctly specified and installed, seals provide effective barriers that both retain lubricants as well as protect against water, corrosion, debris and other contaminants.
Eddy Swiben, branch manager at BDI Canada, explains how to problem solve on an automatic cutter for tissue rolls. âœThis is a very major paper tissue manufacturer that sells paper tissue rolls all over America.â They roll paper tissue just like newsprint paper mills do. When the product is finally done and dried, they need to roll it on a light carton core 20-ft. long.
Bearings are an essential component in the majority of mechanical designs and equipment. It is important to consider the most effective materials when designing industrial machinery, especially in applications where water or other liquids are present. Many materials will be unable to overcome the challenges associated with operating in a wet or corrosive environment.
America suffers $4.4 billion in losses due to earthquakes every year. While that's a drop in the bucket for our $16 trillion plus GDP, it's still a substantial amount of money, and some people are working to lessen those losses. One group is Earthquake Protection Systems (EPS), a company that is designing bearings to better protect buildings from earthquake damage.
I was invited by Tom Astrene of TLT to write a response to the July 2010 TLT article (Ref. 1). My rebuttal â” âœIn Search of a Fatigue Limit: A Critique of ISO Standard 281:2007â â” was published in Tribology and Lubrication Engineering, TLT, August 2010 edition (Ref. 10). While this article is also available online, I will attempt to summarize the essence of my response.
The SKF Generalized Bearing Life Model is (GBLM) an innovative new bearing rating life model that is designed to help engineers calculate bearing rating life in a more realistic manner. The new model is a major step forward for the industry and will play an important role in enabling OEMs and end users to better match bearings and applications, resulting in improved machine life and reduced operating costs.
Large hydraulic cylinders (LHCs) are integral components in the functioning of large machines in mechanically demanding, corrosive and abrasive environments, such as offshore drilling rigs. The materials utilized in these largescale hydraulic systems must deliver reliable performance throughout their expected lifecycle.
Software Design, Analysis and Calculation Tools Help Solve Today's Engineering Challenges
The latest updates in software for bearing design.
Reliability and maintenance engineers can improve uptime and save money on both long-term maintenance and downtime costs by properly diagnosing and correcting bearing vibration issues when they exceed their acceptable limits. This requires inspecting the housing as well as the liner for wear, and replacing them as a pair when the housing is worn, so that wear-in between the mating surfaces can occur.
In case you missed them, following are three recent blog postings by our popular PTE bearings blogger - Norm Parker. We also felt that, should you not be a blog follower, this would be a good way to introduce you to Norm's bearings wisdom. Parker is currently the global senior specialist/roller bearings at Fiat Chrysler Automobiles (FCA).
Until now the estimation of rolling bearing life has been based on engineering models that consider an equivalent stress, originated beneath the contact surface, that is applied to the stressed volume of the rolling contact. Through the years, fatigue surfaceâ“originated failures, resulting from reduced lubrication or contamination, have been incorporated into the estimation of the bearing life by applying a penalty to the overall equivalent stress of the rolling contact. Due to this simplification, the accounting of some specific failure modes originated directly at the surface of the rolling contact can be challenging. In the present article, this issue is addressed by developing a general approach for rolling contact life in which the surfaceoriginated damage is explicitly formulated into the basic fatigue equations of the rolling contact. This is achieved by introducing a function to describe surface-originated failures and coupling it with the traditional, subsurface-originated fatigue risk of the rolling contact. The article presents the fundamental theory of the new model and its general behavior. The ability of the present general method to provide an account for the surfaceâ“subsurface competing fatigue mechanisms taking place in rolling bearings is discussed with reference to endurance testing data.
This issue's focus on bearings includes a number of important and informative articles about one of the most key components in any machine design.
Clutches and Brakes take center stage in the April 2017 edition of Product News.
Design engineers across industries rely on pillow block bearings for a variety of tough and unconventional applications. Having access to data that backs housing strength performance claims is an integral part of choosing the right bearing to keep operations running optimally. What design considerations must be made when the application demands a pillow block installation on a non-horizontal orientation? What happens when bearing load is not applied through the base of the unit? Timken answers these questions with physical testing, advanced modeling and real-world experience to facilitate the selection of pillow block bearings for specific applications.
Ernest Head (Arnie), CBS and technical sales representative at Motion Canada helped save a lumber industry customer time and money by adapting a bearing solution for another client. Hereâ™s how:
Power Transmission Engineering is collaborating with the Bearing Specialists Association (BSA) on a special section within the magazine. Bearing Briefs will present updated reports on bearing topics for each issue in 2016. Complimentary access to all BSA Bearing and Industry Briefs is available on the BSA website at www.bsahome.org/tools.
Thereâ™s nothing quite as satisfying as scoring a goal. Here at Power Transmission Engineering, our goal is to provide you with as much relevant educational and technical material as possible, and every issue we strive to cover the subjects of power transmission and motion control from as many different angles as possible, so that no matter your job title, and no matter your industry, if gears, bearings, motors and related components are important to you, weâ™ve got you covered.
Dale Renner, CBS and sales representative at Bearing Headquarters Co., explains how his bearing expertise helped solve a customerâ™s problem and saved significant downtime and cost.
Michael Odom, certified bearing specialist and customer sales and service at Applied Industrial Technologies, explains how he used his bearing expertise to save a customer both money and downtime.
When rolling element or sleeve bearings operate under extreme conditions, itâ™s more important than ever to follow proper lubrication selection and maintenance procedures to maximize eff ective life and effi cient performance.
Guy Gendron, certified bearing specialist and technical sales representative at Timken Canada L.P. explains how he used his bearing expertise to increase a customerâ™s productivity.
Latest news from around the Industry
Th e ISO defi nition of a full- complement bearing states that the bearing does not have a cage. When that defi nition was written, it was not technically possible to have a full-complement bearing with a cage. But SKFâ™s new high-capacity cylindrical roller bearing combines the load-carrying capacity of a fullcomplement bearing with the benefi ts of a bearing with a cage (Fig.1).
in the performance and life of a rolling element bearing. Less than 10 percent of bearings reach their theoretical L10 life, and poor lubrication can be attributed to 80 percent of those that fall short. Ideally, a lubricant forms a film layer between moving components in a bearing, separating moving parts, minimizing friction and preventing wear between balls or rollers, raceways and retainers. Lubricants also protect metal surfaces from corrosion and moisture, dissipate heat and can even prevent the ingress of contaminants.
The manufacturing process begins in a limestone quarry. Mining methods such as ripping, dozing, drilling and blasting are commonly employed. Limestone provides the first essential component, calcium, for the anufacture of cement. Materials are transported to the crushing plant for further size reduction. Common methods of transport are trucks, loaders and belt conveyors.
Experienced operators can often tell if a machine is not working properly, on the basis that it does not â˜sound right.â™ The same principle can be applied â” using modern electronics â” to identify the exact cause of the problem. Sensitive accelerometers can detect and analyze the vibrations from industrial equipment, highlighting problems such as misalignment or bearing imbalance. The technique is known as vibration analysis. It can identify bearing failure in the very early stages, when there is a microscopic defect on the raceway, for example. The problem is that the identifying signal is usually drowned out in all the other noise emanating from the machine.
Rolling-element bearings are high-precision components that need to be stored and handled carefully to perform as designed. Proper storage and handling of a bearing before, during and after installation is important because once debris enters a bearing, it reduces the life.
A bearing service life prediction methodology and tutorial indexed to eight probable causes for bearing failure and removal are presented - including fatigue. Bearing life is probabilistic and not deterministic. Bearing manufacturers' catalogue (L10) bearing life is based on rolling-element fatigue failure, at which time 90% of a population of bearings can be reasonably expected to survive, and 10% to fail by fatigue. However, approximately 95% of all bearings are removed for cause before reaching their L10 life. A bearing failure can be defined as when the bearing is no longer fit for its intended purpose. For a single bearing, you can only predict the probability of a failure occurring at a designated time - but not the actual time to failure.
Richard (RJ) Seguin, CBS and technical sales representative at AMI Bearings, explains how his bearing expertise tripled the life of a customerâ™s bearings.
Wind is a form of solar energy. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earthâ™s surface, and rotation of the earth. Wind Turbines convert the kinetic energy in wind into mechanical power.
Power Transmission Engineering is collaborating with the Bearing Specialists Association (BSA) on a special section within the magazine. Bearing Briefs will present updated reports on bearing topics for each issue in 2016. Complimentary access to all BSA Bearing and Industry Briefs is available on the BSA website at www.bsahome.org/tools.
Gregory (Keith) Boutwell, CBS and executive account manager at B&D Technologies (a division of B&D Industrial), explains how he used his bearings expertise to save a customer thousands of dollars through correct bearing installation.
End users and OEMs frequently specify "lubed-for-life" mounted bearings, thinking the lubed-for-life bearings will deliver the same life â” without lubrication â” as bearings that currently require periodic lubrication. The truth is it depends on many factors, and only a detailed review of the application and testing will provide a more accurate answer.
Slow speed operation of fan systems within the air handling industry is generally performed due to two reasons: a coast down operation is required for hot (induced draft) fans to cool down before shutdown (often by using a turning gear), and operational efficiency improvements can be achieved during non-peak periods by slow speed operation using a VFD. In either case, when these fans are supported by hydrodynamic bearings, it is the oil film thickness developed from the bearing-shaft interaction that limits the minimum speed that can be maintained without causing premature wear and bearing failure. This paper will present a brief overview of lubrication theory and critical design parameters to achieve slow speed operation.
The complete Product News section from the September 2017 issue of Power Transmission Engineering.
The complete Product News section from the September 2020 issue of Power Transmission Engineering.
As NVH technology advances, so do the tools that allow engineers to study, test, and manufacture bearings capable of delivering high-performance and quality.
In this special advertising section, Power Transmission Engineering features several of the world's leading bearings suppliers and their latest technology.
A discussion of the evolution of condition monitoring for bearings and the upcoming introduction of company's next-generation condition monitoring platform.
Oh my. It's been another busy month here at Power Transmission Engineering, and we have another full issue for you. This time around we have a focus on bearings, with plenty of great examples of applications and technology from the world's leading manufacturers. Of course, bearings are essential to power transmission and a core subject we cover every issue. But when it's the focus, we like to attack the subject from multiple different angles.
Bearings Manufacturers Support Essential Manufacturing by Staying Open through the COVID-19 Pandemic
What is the general consensus on the current quality and viability of global bearing sources for the power transmission industry?
One of the largest components manufactured by Schaeffler last year was a double-row tapered roller bearing featuring an outer diameter measuring 3.6 meters and a weight just over nine tons.
The complete Industry News section from the March 2020 issue of Power Transmission Engineering
Lubrication plays a vital role in the performance and life of rolling element bearings, yet its significance is often underestimated. The most important task of the lubricant is to separate parts moving relative to one another (balls or rollers and raceways) in order to minimize friction and prevent wear. A lubricant that is designed for specific operating conditions will provide a load bearing wear protective film.
This special advertising section features leading suppliers!
Radial spherical plain bearings play a key role in off highway equipment and vehicles
An explanation of the detailed calculation of rolling bearings in the FVA-Workbench based on consideration of the profiling of roller bearings.
The complete Industry News section from the September 2021 issue of Power Transmission Engineering
FVA Software bundles the results and knowledge from hundreds of research projects in one platform.
The complete Product News section from the April 2021 issue of Power Transmission Engineering.
The main function of rolling bearings is to support load and transmit rotational movement with minimum energy loss. In order to achieve this, bearings are manufactured with particularly good quality fatigue resistance materials, proper design and tight manufacturing tolerances. Particular emphasis is put in both the macro, and micro geometry of the working shapes and surfaces of the raceways. Rolling bearings come in many types and sizes as ball and roller bearings for radial and thrust loads.
The complete Industry News section from the December 2020 issue of Power Transmission Engineering.
The complete Industry News section from the March 2021 issue of Power Transmission Engineering.
What trends do you see in bearing materials and coatings that will benefit the power transmission industry?
Whether you design, build or maintain industrial equipment, it is likely you have encountered many types of bearing grease over the years. Lubrication plays a crucial role in virtually all operations, and certain key characteristics allow grease to perform its job better in demanding applications.
Counterfeits continue to vex big-name suppliers
Here's what one supplier is doing to take advantage of the mobile phone in your pocket.
Good machinery can last a lifetime. But, replacement parts for older equipment may be near impossible to find. So, what do you do when you're looking to replace hard-to-find bearings and related parts for older machines?
No one likes paying too much for anything. Everyone wants to get a better deal. That's why you shop around before buying a new car. That's why you look at sale advertisements before buying a new refrigerator or big screen tv. The bigger the purchase, the more you want to compare prices.
Various surface treatment and bearing technology solutions are explored to solve challenging lubrication regimes.
Understanding proper bearing lubrication procedures is critical to ensuring long-term, trouble-free performance. Klüber Lubrication has prepared this explanation as a general guide.
10,000 Year Clock Needs Bearings that Run for 350 Million Cycles.
Automated production of large objects such as auto body prototypes, boat hulls and surfboards traditionally requires computerized numerical control (CNC) systems costing nearly a million dollars. Thomson Cuts Costs and Production Time for Autoscale Inc.
Thrust cone bearings are an elegant option to handle the axial forces generated by the torque transmission in helical-toothed gear stages. They have proven as an efficient and reliable bearing concept for integrally geared compressors but are nearly unknown in other fields of gearbox engineering. The presented investigations consider three aspects which appear relevant to extend the field of possible applications for thrust cones towards gearboxes constructed with roller bearings.
Heat generation in bearings is manifested by the power losses of the transmission. Because of the rise in temperature due to heat generation, the appearance of dilatation adversely affects the bearings' geometrical characteristics.
Rolling element bearings are widely used in mechanical transmission to reduce friction between two rotating parts. With the further development of the electrical motor in mechanical industry, REBs operate more and more at high rotational speed. For these applications, REBs power losses can be predominant in mechanical transmissions.
For a maintenance crew, it is important to know which bearings need re-lubrication and make sure they are lubricating those bearings. The bearings can be lubricated manually or by automatic lubrication systems. This article will review each method and discover its pros and cons.
Special tools and bearing modifications can make removal and installation much safer and easier for plant technicians.
Rheology models express the way tribological conditions translate to shear stress of the lubricant and friction force on the interacting surfaces. Due to the complexity of the lubricant rheology, the friction coefficient is usually obtained experimentally either under the same operating conditions or by curve fitting in a properly chosen friction map. The current study aims at determining the rheological parameters of a lubricant based on friction measurements carried out on a commercial, readily available ball-on-disc machine.
Special advertising section with a focus on bearings.
The complete Industry News section from the October 2018 issue of Power Transmission Engineering.
Wind turbines are getting bigger than ever, and the manufacturing infrastructure that facilitates their construction needs to start growing with them.
The automotive industry is shifting for everyone, bearings manufacturers included. Here's what you need to know to make sure you're shifting with it.
Power Transmission Engineering is collaborating with the Bearing Specialists Association (BSA) on a special section within the magazine. Bearing Briefs will present updated reports on bearing topics for each issue in 2016. Complimentary access to all BSA Bearing and Industry Briefs is available on the BSA website at www.bsahome.org/tools. Additionally, our new Field Notes section on page 34 will feature field reports from BSAâ™s Certified Bearing Specialists.
Iâ™m building a custom gearbox with 7075 T-6 spur gears, and Iâ™m concerned that aluminum flakes will enter the races on the roller bearings (SKF 2307) and cause premature failure. So my question is â” should I place an oil seal on the shaft first to protect the bearing â” or is this an unfounded concern and I should mount the seal in the typical manner outside the bearing? Or both? Or go with a sealed bearing? Iâ™m confused and could use your expertise, please.
American Bearing Manufacturers Association (ABMA) Standard 9 and ISO 281 give equations for calculating the basic dynamic radial load rating for ball bearings. These equations are based on a number of assumptions, many of which are not valid for thin-section bearings. (Thin-section bearings are described in ABMA standard 26.2.) Nevertheless, many thin-section bearing catalogs report load ratings based on these equations. Kaydon has developed a new method for calculating the dynamic radial load rating for thin-section ball bearings. The new method uses the contact stress and the number of stress-cycles-per-revolution to calculate the capacity. The new numbers are based on five years of actual test results. These equations can also be used to calculate the dynamic radial load rating for four-point contact ball bearings, which are not covered in ABMA standard 9 or ISO 281.
The complete Industry News section from the April 2011 issue of Power Transmission Engineering.
The complete Product News section from the June 2011 issue of Power Transmission Engineering.
This article takes a look at alternative-material, non-metal bearings, and it turns out the first bearings of that type - wood, in this case, were the norm - not an alternative.
Based on simulation methods and calculation tools developed by the Schaeffler Group and presented in the first part of this paper, three approaches regarding increased efficiency based on rolling bearings are presented.
Many power transmission components require a certain level of customization for each individual project. The big bearing market is no exception. Construction, mining, steel, marine and wind applications arenâ™t exactly areas where customers buy bearings in bulk.
This article will examine the major materials used to enhance balls to resist aggressive environments and help in selecting the right one.
When your $100 âœRolexâ falls apart on your wrist, well, what did you expect? But when bogus bearings find their way into safety-sensitive applications, lives are at stake.
This Q&A session with various experts at Thomson Linear Systems covers linear slides & stages, clutches & brakes, bearings and actuators.
At first glance, ball bearings are relatively simple mechanisms. However, an analysis of their internal geometries reveals that they are quite complex. For example, the ball to raceway conformity, the radial play, and the number of balls all impact the ability of a ball bearing to support loads under a variety of conditions.
The latest power transmission videos, articles and updates from online.
Air bearings provide a more-precise view of print head variations.
Passenger transport today moves significantly faster than ever before, often operating on separate tracks especially designed for high-speed trains. Accordingly, high-speed rolling bearings are very important components in the bogies of trains today. Maximum train speeds currently reach 380 km/h (236 mph) in the latest high-speed applications - 80% higher than in the earlier days of high-speed traffic. This paper presents two application examples of modern, high-speed traffic, together with some typical bearing arrangements and housings. It provides insight regarding measures taken in the bearing industry to meet the requirements of contemporary, high-speed traffic, and it cites important standards and regulations applicable for - but not restricted to - European applications. To be precise, the focus here is on journal bearings; information on traction motor bearings, transmission bearings and housings is included, but described in less detail.
The complete Industry News section from the June 2012 issue of Power Transmission Engineering.
At a Midwestern producer of tubular steel products, measures taken to counteract the effects of impact on a quench tank roll made it difficult to remove and replace the conventional pillow block bearings that support the rollâ™s shaft.
The availability of high-strength shaft materials, in combination with bearings with high carrying capacity, allows use of slimmer shafts. However, the modulus of elasticity remains the same, so seat design for bearings and gears must be given close attention.
Bearings used to support main spindles on machine tools must be capable of higher speed and greater rigidity. This is true in that any main spindle that turns together with a tool or work piece mounted onto it is one of the critical machine tool components that directly affects machining efficiency and accuracy of the machine tool; and, the bearings that support the main spindle are the most critical machine elements on the machine tool.
The complete Industry News section from the February 2012 issue of Power Transmission Engineering.
A new preventive maintenance program at a leading New England Ivy League university demonstrates how the push for more sustainable "green" building management has led to a growing awareness of a chronic, widespread problem with HVAC motors—electrical bearing damage and failure.
The Bearing Specialists Association explains the role of bearings in ensuring the efficient operation of machinery.
In an industrial application, equipment uptime is vital for on-time performance and profitability. The rotating members of industrial machines are subject to the highest degree of wear and are more susceptible to failure than non-moving parts. Bearing surfaces are the most critical and often the most expensive portion of the rotary assembly; it is imperative to protect these components. The primary protector of these components is the industrial seal.
Power Transmission and control companies will be on hand during Hannover Messe 2013 to display the latest technology offerings in key product categories including roller bearings, gear wheels, pumps, motors, transmissions, drive system components, clutches and braking systems.
Baldor bearings make the grade with Sapphire Recovery and Twin City Fan.
U.S. wind turbine growth puts a new spin on bearing manufacture.
This paper is part 2 of 2 in a series that summarizes the chemical, metallurgical and physical aspects of bearing steels and their effect on rolling bearing life and reliability.
Student research project at Purdue could revolutionize predictive bearing failure.
This paper is intended to enlarge the application range of radial cylindrical roller bearings by means of a more precise determination of thrust load capacity and more cost-effective design.
The ABMA, BSA and PTDA help keep things rolling.
This article describes how more sophisticated modeling techniques allow the latest software to identify design issues with bearings, shafts, gears and complicated multi-body systems.
Rolling element or sleeve bearings often are required to operate under extreme conditions. In these instances, it is more important than ever to follow proper lubrication selection and maintenance procedures to maximize effective life and efficient performance.
Today, better fuel economy is a main objective in the automotive development process. It remains top-of-mind with the auto industry and consumers because of costs and environmental impacts. Because the industry’s average fuel-economy standard is required to increase by 40 percent by 2020, manufacturers and engineers are working to develop fuel-efficient, environmentally friendly and reliable designs for vehicles.
Green technology is more than changing a couple of light bulbs or reducing waste. In 2009, the concept is relevant in every facet of manufacturing as companies make a greater push towards energy efficiency and sustainability. In the power transmission and motion control fields, this technology has been integrated into the daily routine, both as an environmentally friendly business venture and a way to offer green products to customers. Itâ™s apparent that the revitalization of manufacturing, both here and abroad, will center on energy technology.
Bearings with integrated sensors are used in a wide variety of applications, but many potential industrial uses are not yet implemented.
Nitinol 60 (60NiTi), an intermetallic nickel-titanium alloy containing 60 wt % nickel and 40 wt % titanium, is shown to be a promising material for oil-lubricated, rolling and sliding contact applications such as bearings and gears.
Th e signing of a contract for more than 5,000 sets of SKFâ™s latest high-capacity cylindrical roller bearings (HCCRB) for wind turbines will impart added load-carrying capacity, more reliability and longer life to the Nanjing Gear Companyâ™s (NGC) line of gearboxes for wind generation applications.
In todayâ™s increasingly competitive global economy, industries and the companies that serve them are always looking for an edge. Price and quality being routinely accepted as a given, businessesâ”large and smallâ”are always looking for a little help. For the worldwide bearing industry, that help exists in the form of the Bearing Specialists of America (BSA).
The complete Industry News section from the February 2008 issue of Power Transmission Engineering
igus bearings solve undersea issues for the marine vehicle industry.
When a bearing is damaged, it is often removed from service and replaced before it reaches its full, useful and economical life. Advancements in bearing design, materials, bearing maintenance and repair methods have greatly improved the potential for and popularity of bearing repair as an effective way to extend the life of the bearing.
A reader asks whether sleeve bearings can take the place of more expensive tilting pad bearings in a high-speed compressor application.
More than a decade of intensive research and development has resulted in two new technologies that, when used in combination, expand the performance of rolling element bearings well beyond previous limits.
Believe me when I tell you that â” as a domestic automotive engineer â” I bleed U.S. manufacturing. I have never lived more than 50 miles from Detroit,
What is the recommended method of gripping a spinning shaft (with up to 130 hp of rotational energy) to install pre-tension thrust bearings and conventional thrust bearings (load = hundreds of pounds) when the shaft cannot have any high points because it must pass through an area of tight clearances to assemble? Will snap rings still withstand the harsh vibration of this environment?
This paper presents an evaluation of measurements being taken on a 750 kW wind turbine gearbox being tested by the National Renewable Energy Laboratory (NREL). High-speed stage gears and bearings have been identified as critical components of the gearbox; during gearbox testing, these components were instrumented and tests were developed to evaluate loads on high-speed tapered roller bearings (TRBs). In this paper an advanced finite element-based contact modeling procedure has been applied to model the high-speed stage with the bearings fully modeled in order to evaluate strain levels. A major conclusion is that the strains of the slotted grooves are at such a level that they have acceptable signal-to-noise levels. This was verified by the results of the initial experiments presented here.
Wind turbine gearboxes are subjected to a wide variety of operating conditions, some of which may push the bearings beyond their limits. Damage may be done to the bearings, resulting in a specific premature failure mode known as white etching cracks (WEC), sometimes called brittle, short-life, early, abnormal or white structured flaking (WSF). Measures to make the bearings more robust in these operating conditions are discussed in this article.
BEARINGS BASICS Q&A: IN CASE YOU DIDNâ™T KNOWâ¦
Many of us have been there; the bearings had the correct preload. You know it, you were there, and you personally saw the measurements. Now, the testing is done and the preload is gone. Not a little gone, not sort of gone - gone, gone. Finger pointing ensues. Suppliers are dragged in by their wrinkly Polo collars. You know the drill. Losing preload in a tapered roller bearing (TRB) system over the life of your application can be a troublesome problem, particularly for gear sets that are prone to noise or severe applications that rely on a very rigid and stable system.
Videos, tweets, blog posts and other online exclusive from PTE and mechanical power transmission component suppliers.
A reader asks: I have heard that new axles no longer need a break-in period. True or false?
When comparing bearing suppliers, engineers are often left with few options other than to compare dynamic load ratings and corresponding life calculations. Of course, we can look at steel and manufacturing quality; but if we are comparing sources of similar quality, those items may not provide a large contrast. It often surprises people to learn that bearing capacities are calculated values, not tested values. Lately, however, a trend is emerging for bearing suppliers to increase their ratings for higher performance bearings that have premium features such as higher quality steel and specilaized heat treatment. Bearing companies are under intense competitive pressure to make every feature add to the dynamic capacity of their bearings because it is very well understood that an increase in capacity adds to the bottom line.
Engineers typically learn that the bearing L10 life can be estimated using the so called âœC/P methodâ â” or the âœbasic rating lifeâ of the bearing, a method rooted in the 1940s. Major developments have since led to the âœmodified rating life,â released in ISO 281:2007, which includes the aiso life modification factor. In this paper a succession of equations used for bearing life ratings are reviewed, and current bearing life rating practices are discussed in detail. It is shown that â” despite the introduction more than 30 years ago of the adjustment factor of the basic rating life, and the standardization in 2007 of the aiso modification factor â” use of these improved calculation methods are not practiced by all engineers. Indeed â” many continue referring to the old model as a way of seeking compliance with existing, established practices.
Tapered roller bearings can be set at initial machine assembly to any desired axial or radial clearance. This unique feature enables a designer to control bearings to meet anticipated application operating conditions, and thereby provide optimum bearing and system performance.
In 1991, Needelman and Zaretsky presented a set of empirically derived equations for bearing fatigue life (adjustment) factors (LFs) as a function of oil filter ratings.
There are thousands of sizes and types of standard bearings. In many applications, specifying a standard bearing yields an effective result.
The following short articles first appeared on www.powertransmission.com. They are part of the ongoing series of hints, technical tidbits and inside knowledge presented by our resident blogger, Norm Parker. If you like what you see here and are interested in learning more, visit www.powertransmission.com/blog.
At Hannover Messe, Power Transmission Engineering had the opportunity to sit down with Stefan Hantke, president of the Industrial North America division of Schaeffler USA, to discuss the current stateof- the-art in bearings manufacturing, the trends in industrial bearings and the current state of U.S. manufacturing. (In the meantime Stefan Hantke has taken over responsibility for the global sales activities of Schaeffler Industrial)
A four-point contact ball bearing makes it easy to simplify machine designs that combine radial, thrust and moment loads, because it can handle all three simultaneously. They are primarily used for slow-to-moderate-speed applications, or where oscillatory movement is predominant.
During the past three decades there has been an evolution in the advancement and use of highly engineered plastics in bearing applications.
Machine and equipment manufacturers today are feeling more pressure than ever to reduce costs without sacrificing machine performance â” a balancing act difficult to achieve. OEMs often overlook a simple solution that can have a positive, long-term impact on profitability for themselves and their customers, i.e. â” the elimination of bearing lubricant.
A reader asks: I've determined that a stainless steel bearing is the best option for my application. I'm being asked to specify the grade of stainless steel in my product design. I'm not sure which grade to select and specify. Can you help?
What are the best methods to adjust tapered roller bearings?
This paper summarizes the chemical, metallurgical and physical aspects of bearing steels and their effect on rolling bearing life and reliability.
Grease lubrication has clear advantages over oil lubrication: Grease does not leak easily; it has sealing properties; and it protects bearing surfaces from corrosion. Its disadvantages are grease-life limitations and a limited cooling ability. Moreover, in some applications there is a risk of grease starvation, which leads to reduced lubricating films. However, if the right grease, sealing system and/or lubrication system are chosen, then grease lubrication offers clear benefits. This article summarizes aspects of grease lubrication mechanisms in rolling bearings.
For design engineers and purchasing agents alike, bearings can sometimes be like family. Oh, you know - can't live with 'em, canâ™t live without 'em.
Power Transmission Components from Forest City Gear, Kaydon Bearings and Maxon Motors help power NASA's Curiosity Mars Rover.
In this Ask the Expert article, Hans Wendeberg from SKF discusses some of the things you need to know when calculating bearing diameters.
All major manufacturers of 3-phase AC induction motors offer "inverter-duty" or "inverter-readyâ models, but while these motors have inverter-rated insulation to protect the windings, the bearings--their most vulnerable parts--are too often ignored.
Waukesha Bearings is known internationally for its capabilities, technology, size and application experience in the rotating (turbo) equipment industry. Following is a brief selection guide intended to assist engineers, specifiers, integrators and others in choosing the right bearingâ”and bearing technologyâ”for the application.
SMB Bearing Offers Unique Solutions for NorthwoodsFB finger-size skateboards.
For the most accurate measurements, miniature and instrument ball bearing dimensions should be measured with a calibrated air gauge. A good second option is a calibrated optical comparator. On occasion, it may be necessary to use a calibrated, hand-held micrometer to double-check a measurement or for simple verification while working in the field.
Mounted ball bearings are everywhere in industrial applications. They serve critical roles in keeping a manufacturing operation running smoothly and in ensuring that equipment functions properly and reliably. So why might it be advisable to spend significantly more for a dimensionally comparable bearing from one supplier versus another?
A critical problem for wind turbine gearboxes is failure of rolling element bearings where axial cracks form on the inner rings. This article presents field experience from operating wind turbines that compares the performance of through-hardened and carburized materials. It reveals that through-hardened bearings develop WEA/WECs and fail with axial cracks, whereas carburized bearings do not. The field experience further shows that a carburized bearing with a core having low carbon content, high nickel content, greater compressive residual stresses, and a higher amount of retained austenite provides higher fracture resistance and makes carburized bearings more durable than through-hardened bearings in the wind turbine environment.
Bearings that show wear may not always need to be replaced. Depending on the degree and type of wear, they may be candidates for reconditioning, a process that restores bearings to like-new specifications and performance - at an average 50 to 60 percent of the cost of replacement.
The chemical and physical properties of gear oils may change, depending - more or less - upon their formulation and the environmental conditions under which they are used. This is why - after three years of use in a wind turbine - a gear oil was examined to determine if indeed changes were evident and if the protection of the gears and rolling bearings still met the same requirements as would be expected of fresh oil. Our findings revealed that the existing gear oil - as well as its ability to protect the gears and rolling bearings - had degraded very little compared to fresh oil.
The air-oil, two-phase flow inside the multiple-point, oil-jet lubrication ball bearing was studied based on CFD (computational fluid dynamics) theory and technique, and compared with single-point, oil-jet lubrication. The results indicate that the air-oil distribution inside the bearing with multiple-point, oil-jet lubrication is more uniform than single-point injection.
This article summarizes some common hurdles, issues and questions encountered by the newer and casual users of tapered roller bearings.
Collaboration moves bearing modeling and simulation software forward
IFPE offers the right balance of technology and education.
For either brand-new motors or those already in service, "best practices" means that informed technicians can make use of the latest diagnostic techniques (vibration analysis, thermography, shaft-voltage testing, etc.) to prevent electrical bearing damage -- either at the very beginning or very quickly thereafter. If done correctly, the work need only be done once.
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