Articles About life
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Engineers typically learn that the bearing L10 life can be estimated using the so called “C/P method” — or the “basic rating life” of the bearing, a method rooted in the 1940s. Major developments have since led to the “modified rating life,” 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 — 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 — use of these improved calculation methods are not practiced by all engineers. Indeed — many continue referring to the old model as a way of seeking compliance with existing, established practices.
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.
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.
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 surface–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 surface–subsurface competing fatigue mechanisms taking place in rolling bearings is discussed with reference to endurance testing data.
End users and OEMs frequently specify "lubed-for-life" mounted bearings, thinking the lubed-for-life bearings will deliver the same life — without lubrication — 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.
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.
Implementing product lifecycle management strategies can be intimidating at first glance, but it's also necessary. Here's why and how you should implement a PLM strategy of your own.
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.
The U.S. Space Shuttle fleet was originally intended to have a life of 100 flights for each vehicle, lasting over a 10-year period, with minimal scheduled maintenance or inspection. The first space shuttle flight was that of the Space Shuttle Columbia (OV-102), launched April 12, 1981. The disaster that destroyed Columbia occurred on its 28th flight, February 1, 2003, nearly 22 years after its first launch.
Th e primary sources of bearing failure are lack of lubrication and contaminant ingress. Industrial sealing devices are the primary protection against bearing failure. When the sealing device fails, bearing failure is imminent. Th erefore, extending the life of sealing devices extends bearing life and in turn improves equipment uptime.
I was invited by Tom Astrene of TLT to write a response to the July 2010 TLT article (Ref. 1). My rebuttal — “In Search of a Fatigue Limit: A Critique of ISO Standard 281:2007” — 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.
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.
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.
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.
Dust, soil broken rock and other related materials that blanket planetary surfaces—known as regolith—have great potential to contribute to space observation research, but the physical properties of lunar regolith are unique and very difficult to excavate from a technical perspective. A group of students at the Missouri University of Science and Technology, dubbed the Lunar Miners, decided to step up to the plate—that is, by entering the 2008 NASA Regolith Excavation Challenge.
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.
SMB Bearing Offers Unique Solutions for NorthwoodsFB finger-size skateboards.
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.
For the lubrication of open gear drives used in different industrial applications such as cement and coal mills, rotary furnaces, or where the sealing conditions are difficult, semi-fluid greases are often used in preference to fluid oils. For girth gear applications the greases are used with a splash or spray lubrication system. The selection of such greases influences pitting lifetime and the load-carrying capacity of the gears, as well as wear behavior
Richard (RJ) Seguin, CBS and technical sales representative at AMI Bearings, explains how his bearing expertise tripled the life of a customer’s bearings.
Without the sun, there would be no Earth and no life. However, our knowledge about our home star is still very limited. This is about to change. In 2018, the European Space Agency (ESA) will send its Solar Orbiter into space, equipped with a thick heat shield.
When rolling element or sleeve bearings operate under extreme conditions, it’s more important than ever to follow proper lubrication selection and maintenance procedures to maximize eff ective life and effi cient performance.
Modeling and simulation is a key driver of innovation. Whether it’s general manufacturing, consumer goods or life sciences, the ability to realistically model and simulate the response of parts, sub-systems and complete assemblies to increase accuracy and repeatability is vital in today’s analytical world.
Failure to specify the proper motor for use in a hazardous location can have serious consequences - lost production, extensive property damage, and even loss of human life. Selection of the proper motor requires an understanding of Underwriters Laboratories' (UL) and National Electrical Code (NEC) class, group and division designations and the T code letters.
Sustainability is becoming one of the most important aspects within the power transmission business. Users demand low-maintenance drive systems with as little disruption as possible, and expect lifetimes of more than 10,000 hours. Approximately 40 percent of long-term gearbox leakages can be traced back to poor interaction between the radial shaft seal (RSS) and the lubricant. Thus, it becomes essential to analyze the tribological system as a whole, which includes the gear oil, seal grease (if required), elastomer material and design, and the shaft.
rotary-type blowers? Examples: for motor KW; RPM; temperature; pressure production; lifetime; etc. In other words, how do I choose between belts or couplings?
While metal-to-plastic parts conversion actually began way back in the Fabulous Fifties, think toys, household products, etc., it is only in more recent years that plastic conversion has gained a firm foothold in the more strength- and lifetime-demanding applications such as aerospace, under-the-hood automotive, motors, valves, bearings and, as they say, much more.
The following is a very brief overview on the life, work and achievements of Al-Jazari - the most famous mechanical engineer of his time. Now well more than 1,000 years ago,
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.
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.
Equipment downtime and reduced component life are a few of the consequences — and potential costs — 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.
New generation sensors are improving our quality of life.
Motion systems bring award-winning and energy-optimizing “Smart House” to life.
One of the driving forces behind the industrial revolution was the invention—more than a century ago—of the electric motor. Its widespread use for all kinds of mechanical motion has made life simpler and has ultimately aided the advancement of humankind. And the advent of the inverter that facilitated speed and torque control of AC motors has propelled the use of electric motors to new realms that were inconceivable just a mere 30 years ago. Advances in power semiconductors—along with digital controls—have enabled realization of motor drives that are robust and can control position and speed to a high degree of precision. The use of AC motor drives has also resulted in energy savings and improved system efficiency. This paper reviews the development and application of inverter technology to AC motor drives and presents a vision for motor drive technology.
Th e signing of a contract for more than 5,000 sets of SKF’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 Company’s (NGC) line of gearboxes for wind generation applications.
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.
The purpose of DC motor protection is to extend a motor's lifespan by protecting it from conditions that can damage the motor's windings--both electrically and mechanically.
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.
During the qualification campaign of the NIRSpec (near-infrared spectrometer) instrument mechanism, the actuator could not achieve the expected lifetime that had been extended during the development phase. The initial design could not be adapted to the requested number of revolutions during that phase. Consequently the actuator needed to be modified so that the function of the mechanism would not be endangered or, by extension, the overall function of the NIRSpec instrument. The modification included a change of the overall actuator design—internal dimensions, tolerances, materials, lubrication and assembly process—while keeping the interface to the mechanism, mass and function.
This paper summarizes the chemical, metallurgical and physical aspects of bearing steels and their effect on rolling bearing life and reliability.
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.
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.
The following news items offer the latest on lubrication and seal technology in the power transmission market. From bearing greases to high-performance seals, these products will help extend the service life and manufacturing capabilities for a wide range of industrial sectors.
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.
Dovetails, gears and splines have been widely used in aero engines where fretting is an important failure mode due to loading variation and vibration during extended service. Failure caused by fretting fatigue becomes a prominent issue when service time continues beyond 4,000 hours. In some cases, microslip at the edge of a contact zone can reduce the life by as much as 40–60 percent.
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.
News Items About life
1 Rexnord Introduces Targeted Life Gear Sets (October 11, 2013)
Rexnord introduces its newest product offering, Falk Targeted Life Gear Sets, engineered for applications when the life of a mill or mine...
2 Trelleborg Expands Life Sciences Facility (October 19, 2012)
Trelleborg Sealing Solutions continues to broaden its global footprint in the North American life sciences industry with a $ 7.3 million ...
3 QC Industries Offers Lube-for-Life Bearings (December 14, 2007)
QC Industries has replaced its standard bearings with lube-for-life versions featuring a permanent, micro-poly lubricant designed to meet...
4 Force Control Hazardous Brakes Provide Longer Service Life (March 3, 2016)
New MagnaShearT hazardous duty brakes from Force Control Industries, which employ oil shear technology to provide longer service life wit...
5 SKFs New Cylindrical Roller Bearings Extend Wind Turbine Gearbox Life (April 11, 2006)
New SKF high-capacity cylindrical roller bearings for wind turbine gearboxes have been engineered to promote longer gearbox service life...
6 SKFs New Cylindrical Roller Bearings Extend Gearbox Life (April 9, 2006)
New SKF high-capacity cylindrical roller bearings for wind turbine gearboxes have been engineered to promote longer gearbox service life...
7 Linear Actuators Improve Performance and Life (May 29, 2008)
Haydon Switch & Instrument, Inc. recently announced that its size 14 hybrid linear actuators are now available with an integrated c...
8 Actuator Offers Long Life and Static Load Capacity (December 13, 2010)
Linear motion control systems and turnkey components manufacturer Nook Industries has recently introduced the Infinity 1 Roller Screw Act...
9 Bullock Presented Lifetime Achievement Award (October 25, 2010)
At its 2010 Manufacturing and Wholesale Distribution Executive Summit in Rosemont, Illinois, RSM McGladrey presented its Lifetime Achieve...
10 ITW Rocol's Lubricant Applied to Grinding Wheels to Increase Belt Life (July 9, 2007)
Accu-Lube Stick lubricant is a ready-to-use lubricant stick that is applied to the tool before start-up. Accu-Lube Stick can be used on g...
11 Former Boston Gear President Receives PTDA Lifetime Achievement Award (April 15, 2006)
Roger A. Pennycook, former president of Boston Gear and former vice president of Textron Fluid & Power Co., was the 17th recepient...
12 NSKs New Bearing Designs Deliver Longer Life, Higher Speeds in Papermaking Machines (March 2, 2007)
Rolling bearings used in the production of paper undergo a continuous production cycle, are required to handle high-temperature condition...
13 Sauer-Danfoss H1 Motors Lower Fuel Consumption and Life Cycle Costs (May 17, 2011)
Sauer-Danfoss has released its new H1 160cm3 bent axis motor, the next size in a series of motors designed to complement the growing rang...
14 Cam-Clutches Deliver Greater Torque Capacity, Longer Fatigue Life (February 14, 2008)
Tsubaki recently introduced a range of cam-clutches designed for back-stopping operations in light-duty applications at high RPM. The MRE...
15 Cyclone Effect Extends Filter Lifetime (June 8, 2012)
The new developed In Line Filter (LEN) by Rexroth offers significantly improved performance. A new design, using the cyclone effect in th...
16 Pacamor Kubar Estimates Life of Miniature and Instrument Ball Bearings (February 8, 2016)
Life" is the number of hours that a percentage of similar bearings have survived under an essentially identical set of operating con...
17 Hydraulic Institute Presents Lifetime Achievement Award (February 25, 2016)
The Hydraulic Institute (HI) recognized and honored Jack Claxton, vice president, engineering, Patterson Pump Company, as its Lifetime Ac...
18 Festo Semi-Rotary Drive Designed for Long Life and Fast Installation (August 18, 2016)
Festo has introduced a new pneumatic semi-rotary vane drive and matched contactless position sensor that transforms a relatively simple a...
19 Hydraulic Institute Announces Lifetime Achievement Award Recipient (April 4, 2017)
The Hydraulic Institute (HI) has recognized and honored Albert Huber, president, Patterson Pump Company, as its 2016 Lifetime Achievement...
20 Dan Jones Receives EMERF Lifetime Achievement Award (January 7, 2015)
Dan Jones, president and owner of Incremotion Associates, recently received the EMERF 2014 award for “Outstanding Contributions to ...
21 REO-USA Increases Motor Lifespan (August 26, 2014)
In mission critical industries such as pharmaceuticals or paper and pulp, a motor malfunction can translate to millions of dollars in los...
22 Zero-Max Right Angle Gear Drives Ensure Lifetime Lubrication (May 2, 2017)
Lifetime lubrication in Zero-Max “Crown” gear drives assures motion system designers of a smooth operating, quiet right angle...
23 Igus Chainflex Offers Long Service Life (July 11, 2013)
For over 20 years, Igus has been rigorously testing the durability of its Chainflex continuous-flex cables in its 19,000 square foot labo...
24 Emerson Offers LifeCycle Engineering Services (March 4, 2014)
Power Transmission Solutions, a business of Emerson Industrial Automation, offers a new model for enhancing the performance of critical m...
25 Victrex Increases Lifetime of Sliding Bushing in Water Pump (April 11, 2012)
Automobile manufacturers are feeling the pressures of obtaining improved fuel economy and lowering maintenance costs for owners. One solu...