Archive | Lubrication

1067

11:12 pm
February 18, 2015
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Lubrication Checkup: ISO 55001 Certification

0814lubecheckupBy Dr. Lube, aka Ken Bannister

Symptom:

“Our company wants the maintenance department certified to the new ISO 55001 Maintenance Standard within two years. Should we update our lubrication practices?” 

Diagnosis:

Any opportunity to review and update your lubrication practices should be embraced. A well-managed lubrication program is an integral part of any asset-management program, and lends itself to ISO standards like 55001-Asset Management, 50001-Energy Management and 14001-Environment Management. ISO 55001, which debuted as a global standard in 2014, is tailored to the maintenance and reliability community. Focusing on the life-cycle management and value of a corporation’s assets, it encompasses all lubricated machinery and physical assets.

Prescription:

Preparing for certification will require an internal audit of your current maintenance strategies, methods, processes and procedures to ensure they align with the standard’s requirements. ISO 55001 demands that the asset-management group’s approach to maintenance directly align with corporate values, goals and objectives. For example, a company may have holistic stated objectives involving energy use/savings and environmental sustainability edicts. It will also have business objectives that could include increased service levels and manufacturing throughput and reduced capital spending and/or operating costs.

To certify, a maintenance department must clearly demonstrate corporate alignment of its asset-management approach (e.g., asset-management system). This includes maintenance policy, strategic asset-management plan, asset-management goals and objectives, and development and implementation of plans and reports to validate the system’s effectiveness. ISO 55001 calls for a value-based approach toward assets to assure their dependability (e.g., availability, reliability, maintainability and maintenance support) and life-cycle-costing/management.

Effective lubrication practices are crucial to the dependability and life of physical assets and their moving parts. The hallmarks of a best-practice lubrication program are those designed to meet the needs of the asset(s), improve the maintainability process, increase production/operations quality and throughput, and help reduce corporate energy use and carbon footprint with minimal capital outlay.

Yes, ISO 55001 is a great opportunity to review your current practices and implement an integrated, lubrication program designed to help you meet your certification requirements. Certification, and the process to achieve it, will also help you better serve your company, clients and assets. Good luck! MT

Ken Bannister of Engtech Industries, Inc., is a Lubrication Management Specialist and author of Lubrication for Industry (Industrial Press), and the Lubrication section of the 28th Edition Machinery’s Handbook (Industrial Press). For in-house ICML lubrication-certification training, contact him at 519-469-9173 or kbannister@engtechindustries.com.

104

7:41 pm
February 18, 2015
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Procuring The Highest-Quality Oil Sample

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Oil samples can reveal a lot about the condition of your equipment. Make sure they’re accurate.

By Ken Bannister, Contributing Editor
kbannister@engtechindustries.com

As in all aspects of life, the end result of any endeavor is only as good as the effort put into the exercise and the quality of elements used to create the result. Such is the case in lubricant and wear-particle analysis. Here, accuracy of results is highly dependent upon the care and method used to collect and then deliver a quality used-oil sample into the hands of a laboratory for analysis.

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Procuring and delivering an analysis-ready, superior-quality used-oil sample requires discipline and consistency, as summed up in the “7 Best-Practice Principles of Oil Sampling” in Table I. Choosing the best procedure, method, hardware and sample location is key. These choices will likely differ based on whether they are taken from a pressurized or non-pressurized system, and whether the machine or gearbox is designed or set up for best-practice sampling techniques. They may also differ due to the consistency of the sampling methods, the training of the person taking the sample and the sampling cleanliness protocol used.   

The best sample choices for a piece of equipment are driven by three main objectives: 1) to maximize sample data density; 2) to minimize sample-data disturbance; and 3) to maximize sampling consistency.

Data density

Each oil sample carries a unique time-stamped composition signature of base oil chemistry, additive-package level and chemistry, and wear-particle type, size and count. These factors are then compared against a virgin oil sample to determine the oil’s chemical condition and the machine’s moving-parts condition at that moment in time. In turn, the more representative the sample is, the more accurate the diagnosis. Every sample, consequently, must contain the maximum amount of data density (representative data) it can—which is best achieved by extracting the sample in the most appropriate place.

For pressurized systems, e.g. hydraulic, and recirculating oil systems, oil is pumped from a reservoir under pressure, through a series of filters in a piping distribution system to the bearing surface areas, from where it is returned to the reservoir to be once again filtered and cooled for recirculation. Maximum data density is always found downstream of the lubricated bearings and upstream of the return filter, where it is laden with contaminants that have just been washed from the bearing surfaces. To assure the most representative sample, take it:

  • When the machine is running at temperature and under regular working condition load.
  • From a live fluid zone, meaning no dead pipe legs (static areas) or line ends.
  • From a sample port connected to an elbow used to create a turbulent zone and ensure a colloidal (well-mixed) sample.

Samples can be extracted in a low-pressure (LP) system using a simple ball valve drain tap screwed into an elbow. For high-pressure (HP) systems, a ball valve can still be employed, but with the addition of a helical coil attachment used to reduce the pressure of the fluid stream once the valve is opened. A more sophisticated way to take HP samples is to use a vacuum pump connected to a push-style sample port (similar to the way a grease nipple works): The probe attached to the pump is inserted into the spring-loaded sample port to allow pressurized oil to flow into the sample bottle that’s screw-attached to the vacuum pump unit.

For non-pressurized systems such as a self-contained splash- or bath-lubricated gearbox, a sample can be extracted three ways. The first (and least desirable) method uses a simple ball valve screwed into the reservoir drain port. Although easy to set up, a large flush volume is needed prior to taking the actual sample—and the user still runs a high risk of picking up sludge contamination from the bottom of the reservoir. (To lessen this risk, a pilot sample tube can be inserted to the one-third level mark of the reservoir.)

The second method employs a drop tube attached to a rod to ensure the tube opening is approximately positioned at the one-third reservoir level mark when the tube is lowered into the reservoir through a fill opening. This is done to help ensure no non-representative sludge contamination is allowed in the sample. The tube is then connected to a suction or vampire pump to extract the sample. Again, sample disturbance can be high if the sampling procedure is not performed carefully.

The third and ideal sample method employs a combination pilot-tube/level-gauge device affixed at the correct reservoir sample level. As most reservoirs don’t come with such devices, this approach will require an after-market equipment purchase and installation

Data disturbance

It’s important that your oil-sample data be neither disturbed nor contaminated by the actual sampling and sample-handling processes. For example, if they’re not minimized, reservoir sludge, dirty sample/drop tubes and dirty sample bottles can all distort data readings. Simple, but effective, tactics for managing data disturbance, sometimes referred to as “interference,” include:

  • Cleaning hands, cleaning the sampling port/area, cleaning sampling equipment.
  • Using only virgin sample bottles designed for oil-analysis sampling (glass is preOnly filling sample bottles 60% to 70%, providing headspace that lets the lab agitate and successfully re-suspend the solids for testing purposes.
  • Performing the 10x flush rule for every sample, e.g., flushing the sample valve and tube (when used) with approximately 10x the required sample-volume space of the oil that’s to be sampled into a non-sample container before the real sample is taken.
  • Using a ziplock sandwich bag as a glove to handle clean sample containers, that when filled, can be stored untouched, ready for shipping (thus minimizing the time sample bottles are open to the elements).

Sampling consistency

To ensure high-quality sample results that can be trusted, the sampling protocol must assure consistency. This is achieved by:

Developing an engineered oil-sampling program in which every sampling port and method is documented and regular sampling frequencies are set up in a work order system. (Commencing such a program, bearings are usually start-sampled on a 500-hr. frequency; industrial hydraulic systems on a 700-hr. hour frequency, light-duty gearboxes on a 1000-hr. frequency; and heavy-duty gearboxes on a 300-hr. frequency.)

  • Using an oil-sampling program to develop, as well as train on, standard operating procedures;
  • Always sampling from the same location.
  • Regularly sampling virgin-oil when new lubricant stock arrives on site.
  • Using the same laboratory for sampling, and ask for dedicated lab technician(s) to perform your plant’s sampling.
  • Always filling in the sample-data form accurately, including sampling date and time stamp.   
  • Sending a sample to the lab within 24 hours of its collection (if longer than 24 hours, the sample must be retaken).   

Ken Bannister is a certified Maintenance and Lubrication Management Consultant for ENGTECH Industries, Inc. Contact him at 519-469-9173 or kbannister@engtechindustries.com.

196

7:29 pm
February 18, 2015
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The Inner Life of Bearings, Part 1: How Lubrication Really Works

What some personnel don’t know can hurt your equipment and processes. Expert advice bears repeating.

By Neville Sachs, P.E.

As a facility considers implementation of a sophisticated lubrication program, it’s not uncommon for someone to strongly insist that “oil’s oil,” and that “all our applications can be handled by one multi-purpose grease.” The numbers of mineral-based and synthetic lubricants in vendor catalogs run counter to those arguments. Manufacturers commonly list over 40 greases and lubricating oils, available in at least 10 viscosity ranges. Categories include aviation oils, automotive and light truck engine oils, gear oils, compressor oils, heavy-duty engine oils, gas engine oils, turbine oils and way oils, to name but a few.

Accounts of someone’s brother-in-law or friend who “never changed the oil in his truck,” or “used ATF (automatic transmission fluid) in his car engine,” may be more urban legend than truth—and they don’t reflect lasting solutions: Some oils will temporarily work in an incorrect application, but they won’t provide long, reliable service. Unproven theories and/or ill-informed theorists should carry no weight in a facility’s approach to lubrication, but often do.

Overcoming the harmful impact misinformation and flawed thinking can have in today’s industrial operations calls for continuous emphasis on correct information. This two-part article recaps lubrication fundamentals that have been covered in these pages before. But when it comes to the bearings in your plant’s critical equipment systems—and the ever-changing workforce that may be maintaining them—regular reinforcement of these principles is crucial.

Back to the basics

Friction, lubrication and wear (i.e., “tribology”) constitute a complex body of knowledge that involves, among other things, three basic types of bearings with very different “wear-prevention” mechanisms and critical point-of-contact temperatures.

For lubrication to be effective, a bearing’s mating pieces must be separated. In conventional plain bearings and rolling element designs, this separation depends on the lubricant’s viscosity. The success of a sliding application is governed by the lubricant’s additive package.

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One of the most important aspects of lubrication is relative lubricant film thickness. Figure 1 illustrates this film thickness by depicting two pieces of metal as viewed through a microscope. Note that these pieces are not perfectly flat: R1 and R2 refer to their average roughness measurements. Between the two pieces, h is a measure of the separation resulting from the lubricant. Represented by the symbol λ, relative film thickness is calculated as:

λ =  h/(R12 + R22)1/2

Within reason, the greater the λ value, the lower the wear rate.

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Another important principle of lubrication can be seen in the Stribeck Curve in Fig. 2. Developed in 1902 by the German engineer and scientist Richard Stribeck, it shows how the coefficient of plain-bearing friction varies with surface speed and lubricant viscosity. Referring to the diagram, we can see that when a lubricant is supplied and the surface speed between two properly designed parts increases, the friction first rapidly drops off,  then slowly increases. This curve is also helpful in that it shows the three lubrication zones—which basically equate to the three most common bearing types. Low-speed plain bearings and sliding applications fall into the boundary-friction zone; ball and roller bearings into the mixed-film (elastohydrodynamic) zone; and high-speed plain bearings into the full-film zone.

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The plot in Fig. 3 uses somewhat different terminology than the Stribeck Curve for the three lubrication zones. It also shows the effect of relative film thickness on wear rates. Hydrodynamic lubrication typically is seen in plain bearings, i.e., in automobile engines and large turbines and generators. Elastohydrodynamic refers to the lubrication mechanisms seen in higher-speed rolling element bearings. Sliding (boundary-friction) lubrication occurs in applications like piston rings, wire ropes and slow-speed rolling element bearings.

How different bearing types operate

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Lubrication occurs in the three categories of bearings by way of very different mechanisms. The diagram of a hydrodynamically lubricated plain bearing in Fig. 4 shows a journal that rotates inside the bearing. (The bearing can be made from any one of many materials, which will be discussed in Part 2 of this article.) Preferably, oil is fed into the gap at the unloaded area of the bearing, whereupon it is swept around the journal. In the process, the oil viscosity develops a wedge that separates the two pieces. The typical film thickness is in the order of 0.01 to 0.05mm (0.0004” to 0.002”). While this type of bearing can withstand tremendous pressures, as the load on it increases, internal shearing of the oil film increases the lubricant temperature, the viscosity drops and leakage increases.

Photo 1: As shown by the uneven wear pattern on this pair of gas-engine main bearing inserts, misalignment and excessive clearance will reduce the life of plain (i.e., hydrodynamically lubricated) bearings.

Photo 1: As shown by the uneven wear pattern on this pair of gas-engine main bearing inserts, misalignment and excessive clearance will reduce the life of plain (i.e., hydrodynamically lubricated) bearings.

Designing a hydrodynamically lubricated bearing primarily involves understanding operating temperatures and viscosities and the need to create a system that delivers more oil than can readily leak out from the edges of the bearing. Misalignment and excessive clearance will greatly reduce the bearing’s life. (As shown in Photo 1, the uneven wear pattern on a pair of gas-engine main bearing inserts contributed to their rapid degradation.)

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As can be seen in Fig. 5, rolling element bearings, ball and roller bearings, have vastly different lubrication mechanisms.

In the operation of a ball or roller bearing, as the element rolls along and traps that easy-flowing oil, viscosity changes significantly (increasing by a factor of 10,000 or more and becoming stiff enough to actually separate the rolling element from the ring). As this occurs, the mating areas of the element and ring flatten elastically to distribute the load across the film and support continued operation. While the lubricant film separation isn’t great (less than a micron [≈0.00004”]) and the pressure is tremendous (typically more than 2GPa [150,000 psi]), the overall effect is substantial: Contact forces are distributed over a much greater area, fatigue stresses are reduced and bearing life is increased.

Photo 2: The inner ring of this spherical roller bearing exhibits the fine-grained spalling that results from inadequate lubrication.

Photo 2: The inner ring of this spherical roller bearing exhibits the fine-grained spalling that results from inadequate lubrication.

Two important factors in this process are lubricant temperature—i.e., the lower the viscosity the thinner the film—and lubricant cleanliness: Because the lubricant film is so thin and the pressures so high, solid particles and water have huge effects on component lives. (Photo 2 shows the inner ring of a spherical roller bearing and the fine-grained spalling that results from inadequate lubrication.)

Photo 3: The dark bands alongside this bearing’s ball paths are oxidized oil deposits.

Photo 3: The dark bands alongside this bearing’s ball paths are oxidized oil deposits.

With the third lubrication mechanism, i.e., in sliding bearings, additives are more critical than oil viscosity. Some additives, such as oxidation inhibitors, are designed to improve oil life. Others, such as anti-wear and high-pressure (EP) additives, are designed to improve oil performance. (The dark bands alongside the ball paths shown in Photo 3 are oxidized oil deposits.)

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Although selection of the correct additive package is important for the lubrication mechanisms shown in Figures 4 and 5, with sliding applications (Fig. 6), the correct additive combination is the key to low wear rates and long component life.

The diagram of contacting metal pieces shown in Fig. 6 could represent piston rings or, alternately, rolling element bearings operating at a speed too low to generate a viscosity conversion. To reduce wear rates in these components, two general types of additives are used: anti-wear (AW) and, as they are known in North America, extreme pressure (EP). (Note: In the rest of the world, extreme pressure additives are characterized as “high pressure.”)

Anti-wear additives are almost always polar molecules—meaning they are compounds that have a positive charge on one end and a negative charge on the other. Because of their polar nature, they are attracted to the metals. An example of this is oleic acid, a fatty acid where one end of the molecule is attracted to the metal and the other end is repelled. With relatively low pressures and low contact temperatures below 100 C, these additives provide a cushion between the two sliding pieces. But at higher-point contact temperatures (and higher pressures), they lose strength and EP additives are needed.

There are two general types of EP additives: liquids and solids. Liquid additives in EP oils are generally compounds of sulfur and phosphorus, and sometimes chlorine, that, when heated, form hard semi-metallic coatings that provide the actual wear resistance. Solid additives found in greases commonly include molybdenum disulfide, graphite and other materials designed to slide between opposing metal parts to provide wear resistance. The proportion of solids varies with individual manufacturers. When using EP lubricants, keep these points in mind:

  • When water is present, some additives will form extremely corrosive chemicals.
  • Solid EP additives tend to disrupt the viscosity transformation that’s critical to higher-speed ball and roller bearing lubrication. (However, if those ball and/or roller bearings are in a gearbox, using EP additives to help preserve the gears is usually much more important than the life of bearings that can be easily monitored and replaced.)

Coming up

Part 2 of this article will focus on oil and grease selection for an application; why speeds and temperatures are important; and why operating environments are critical in determining lubrication frequency.

Neville Sachs has extensive experience in machinery reliability and lubrication. The author of two books on failure analysis and a contributor of sections to other books, he has also written more than 40 articles. A Professional Engineer, Sachs holds STLE’s CLS certification, among others. Contact him at sachscracks@att.net.

72

7:24 pm
February 18, 2015
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From Our Perspective: Revisiting the Power of Twofers and Threefers

kennewmugBy Ken Bannister, Contributing Editor
kbannister@engtechindustries.com

Prior to the Christmas break I was fortunate to visit England with my eldest son and spend quality time with my elderly parents who were celebrating their 60th wedding anniversary. Because geography has rarely favored such multi-generational get-togethers and, taking advantage of the situation as parents often do when grandchildren are around, they relished “spilling the beans” about my youthful traits and transgressions—much to the delight of my adult son! During one of their reminiscences, I experienced a “eureka moment,” recognizing a very specific trait instilled in me as a child that I still employ today. 

As a post-war-England baby boomer, I lived over half my childhood in a frugal world of government rationing with little money to spare for luxuries. With two competing siblings, I was taught that if I wanted something special, I had to present a rational reason for granting my request—essentially make a business case built on need first, want second—for the request to even be considered. In the early days, such prized requests included listening to a rock n’ roll radio program (and, later, television programs), staying up late, using the phone, borrowing the family car, etc.

I learned early on that success was more likely when I reasoned with a holistic view, which my parents called as my “twofer and threefer” approach. I always asked for something I thought was obtainable, and tried to make it easier for them to say yes by spelling out a minimum of two or three benefits for granting my request. For example, I recall my reasons for wanting to watch
Top of the Pops (Britain’s answer to The Ed Sullivan Show) as 1) it allowed me to watch and listen to musicians and study guitarists’ finger positions that would help me learn the guitar; 2) my siblings could watch it with me, and my parents could spend a half hour together in peace; and 3) music would help me become a better person. My approach usually worked. I loved that show!

Thus, it was interesting to see that when the ISO 55001 Asset Management Standard was released last year, it also looks for an asset-management program to deliver its own twofers and threefers. It tasks the organization with demonstrating proof of how its asset-management strategies, plans and objectives directly and holistically align with corporate objectives and culture. It also recommends the same program be designed to meet the identified needs of all program stakeholders.

When an industry employs mechanical equipment, one of the least expensive and most productive means of improving asset function and management is through the design and implementation of a best-practice asset lubrication-management program. This produces obvious internal benefits—increased asset availability, reduced downtime, reduced bearing failure, etc.—that result in a measurable twofer: one for maintenance (by reducing maintenance costs), and one for production (by increasing production throughput). There are other benefits, too,  which can include:

  • Reduced purchase costs through lubricant consolidation
  • Reduced lubricant and replacement-bearing inventory costs
  • Reduced lubricant stock-rotation requirement
  • Increased inventory real estate
  • Reduced lubricant waste
  • Reduced bearing friction
  • Reduced carbon footprint and emissions
  • Improved ability to meet ISO 55001 and other standards requirements

If you are looking to validate the implementation of an asset lubrication program, consider all your stakeholders and position your request based on how the intended program will benefit each. Make it easy for the corporation to say yes. I guarantee you will find more than the usual twofer or threefer in your reasoning, and will be more successful in future requests. Good luck!    

52

9:52 pm
December 14, 2014
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From Our Perspective: The Study

kennewmugBy Ken Bannister, Contributing Editor

In 1964, Professor H. Peter Jost published the results of the world’s first major study on the effects of “Lubrication, Friction and Wear.” His research had been commissioned by the British government, which was keenly interested in these effects on the nation’s Gross Domestic Product (GDP).

Jost’s study proved to be sensational. Industry was astounded by its documentation of the costs associated with poor or ineffective lubrication practices. He found that reversing the trend and making lubrication practices more effective could conservatively save British industry 20% in maintenance and repair costs; 20% in lubricant costs; 7.5% in energy costs; and significant downtime. For his part, Jost received a knighthood and, more important, assured his legacy by naming the study and practice associated with lubrication, friction and wear: He called it “Tribology.”

Six years later, in the hallowed halls of Massachusetts Institute of Technology (MIT), Dr. Ernest Rabinowicz built on Jost’s work and completed his formative study on the “Design, Friction, and Wear of Interacting Bearing Surfaces.” This led to his publication of the seminal tribology text Friction and Wear of Materials, and assurance of his legacy as a lubrication pioneer with the “Rabinowicz Law” that stated, “Every year, 6% of the GDP is lost through mechanical wear.” In his studies, Rabinowicz concluded that 70% of bearing-surface loss of usefulness (bearing failure) is attributed to mechanical wear (50%) and corrosion (20%). Both of these wear mechanisms, we now know, are entirely preventable with Good Lubrication Practices (GLP).

Fast forward 50 years: Great strides have been made in the science of Tribology, particularly in the fields of lubricants and bearing-surface technology—progress that has been driven primarily by the automotive industry and U.S. space program. Additionally, the past 10 years have witnessed significant growth in lubrication awareness through training and certification of lubrication-related personnel by the International Council of Machinery Lubrication (ICML), the Society of Tribologists and Lubrication Engineers (STLE), and the International Organization for Standardization (ISO). Lubrication-delivery systems have also greatly improved, especially in the area of electronic control and programming, and are now affordable to the point that their return on investment (ROI) can be measured in weeks and months in most cases.

Yet, despite our innovation and knowledge in these areas, in my capacity as an asset-management and lubrication specialist, I still see too many needless lubrication-related failures and ineffective lubrication practices in every type of industry. But why? Industry needs more than anecdotal information.

With that in mind, I recently worked with the editorial team at Maintenance Technology magazine to develop and conduct a comprehensive (37-question) online reader survey entitled “State of the Nation’s Lubrication Practices.” The Lubrication Nation’s response to it has been significant.

We asked the who, what, when, where, why and how pertaining to your lubrication practices and received a healthy number of fully completed responses from a variety of industry sectors, including manufacturing, automotive, natural resources, pharmaceutical, food and facility management. The results are telling.

In the next few pages, we share some of what our survey told us about North America’s lube practices and provide an initial explanation of what those responses indicate. Look for upcoming articles in Lubrication Technology and on LubricationTechnology.com that respond to and expand on the needs revealed by the study.

For now, please turn to page 4 to read this first article. Over time, I challenge survey respondents and those who were unable to participate in this study to use its findings as a lens through which to view your respective organizations’ states of lubrication; resolve to make positive changes in your practices; and always celebrate your lubrication-program successes. Good luck!    

59

9:49 pm
December 14, 2014
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Optimize Machine Health with Precision Lubrication

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By Jane Alexander, Managing Editor

Whether you call it world-class, best-practice or use the currently popular term—precision—the procedure is the same when it comes to lubrication: using the right lubricant for your equipment, in the right amount and at the right frequency. And it requires that lubricant condition be managed.

Jarrod Potteiger of Des-Case explains that the precision approach also excludes two common lubrication practices: the default use of high-quality lubricants and routine over-lubrication. Many steps are required to get a significant benefit from high-performance lubricants in most machines, and performing lubrication tasks at intervals shorter than those required is a waste of time and resources at best, and can lead to component failure at worst. Precision lubrication requires that lubrication PMs be rationalized and optimized to ensure that lubricant conditions and amounts will provide the most effective lubrication. Potteiger offers the following advice on developing and maintaining successful precision-lubrication programs.

Lubricant specs

Program success starts with having the right lubricant—oil and/or grease—in every component. This is probably the simplest precision-lubrication aspect to achieve, yet is rarely done right. Lubricants are often specified incorrectly due to initial misinterpretation of OEM specs or, over time, due to a misdiagnosed problem or misplaced perception of benefit. Whatever the reason, Potteiger says, it’s usually prudent to go through each lube point in a facility and verify or correct the lube specs if it has not been done recently. When specifying lubricants, however, he adds that it is important to not just create a proper spec, but to define the methods by which decisions are made. Doing so eliminates future questions about the accuracy of the selection.

With regard to accuracy, Potteiger notes that while it’s not uncommon for machines to have the wrong oil in them, grease is a different story. As he describes the situation, “Most maintenance professionals don’t really understand grease.” Rather, they tend to characterize different greases by the type of thickener they use or by vague terms such as “hi-temp.”

Grease, though, is actually just thickened lubricating oil. The purpose of the thickener is to hold the lubricating oil in place (like a sponge)—not to provide lubrication. For the most part, grease specification should use the same processes as oil, but with additional considerations.

According to Potteiger, the misunderstanding of grease runs so deep that many OEMs don’t provide adequate descriptions for grease specification. In a precision-lubrication program, each lubricated component should have a generic lube spec that identifies viscosity grade, base oil type and the proper additive system. Grease-lubricated components should have the same, and should include thickener type and NLGI grade.

Application amount and frequency

With the proper lubricant installed in every application, the rest of a precision-lubrication program is designed to ensure the proper condition of those lubricants. Lubricant condition has two components: 1) that the lubricant be suitably free of contaminants; and 2) that the lubricant be in acceptable condition from a chemical and performance standpoint. For oil, this means maintaining the proper oil level and replacing it at the right frequency. For grease, it means installing the correct amount initially, then replenishing with the correct amount at the right frequency going forward.

Oil-fill levels and replacement frequencies are typically pretty straightforward, Potteiger says. “OEM instructions usually cover this adequately.” Correct oil levels, however, can vary for similar components, based on factors such as their orientation or operating speed. OEM oil-level instructions should be reviewed carefully to determine that there is either a single, correct level or that the correct option has been chosen if there is more than one.

Oil-replacement frequencies can also vary. Typical recommendations are conservative because, to be on the safe side, the OEM must recommend for harsh operating conditions. Actual, useful oil service life, however, can vary dramatically. Factors such as high operating temperatures, wear debris, moisture and sludge can shorten oil life. In a given application, the severity of these items, or lack thereof, can alter useful service life by an order of magnitude. Nonetheless, most oil-change frequencies for similar equipment can fit into neat periods, such as three, six or 12 months, and should only be scrutinized when severe conditions exist. Use of oil analysis allows for oil to be replaced based on actual conditions, which, in turn, removes guesswork.

As with grease selection, grease application amounts and frequencies are often wrong. For grease-lubricated bearings, Potteiger says, the most common mistake is “too much grease too often.” This is especially true for electric motors. “The real problem,” he explains, “is that most people don’t realize they have a problem.” When the problem is recognized, correcting it is a simple, though time-consuming process that can depend on tapping several resources for information, including bearing manufacturers, electric-motor manufacturers and lubrication textbooks, among others.

To determine the proper initial fill amounts and replenishment rates for grease-lubricated bearings, one needs to know the bearing sizes, speeds and types. Secondary considerations such as temperature, vibration, contamination and bearing orientation are also important to know for fine-tuning default values. Whichever combination of factors is chosen, it is essential to use a consistent source for both amount and frequency determination.

Contamination control

While it’s a given that use of the correct lubricants—and ensuring that they are in suitable chemical condition—is a pre-requisite for success, Potteiger notes that big (i.e., positive) changes in the service-life of components can be achieved through the aggressive management of contamination. In most cases, he notes, the amount of particle contamination in oil is the single biggest factor that determines how long a lubricated component will last. “Many maintenance professionals,” he says, “don’t realize they have a problem with lubrication-related failures because they don’t properly characterize the failure or root cause. Most equipment failures are, in fact, lubrication-related.”

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The normal way in which most machines fail is to “wear out,” but wear rates can be controlled, and the primary purpose of lubrication is to do just that. Studies show that approximately half of lost machine life is due to mechanical wear—and, as shown in Fig. 1, approximately 80% of mechanical wear is caused by particle contamination in the oil. It therefore stands to reason that when particle contamination is reduced, wears rates go down and component service life goes up.

Effectively controlling contamination requires, among other things, a good strategy. Potteiger says that while implementing a contamination-control policy may take time and effort, developing the strategy is rather simple:

Step 1: Identify goals in the form of target-lubricant cleanliness and moisture limits for different types of machinery.

Step 2: Identify all potential measures to improve cleanliness.

Step 3: Verify the effectiveness of implemented measures with oil analysis.

The two basic approaches to controlling lubricant contamination are exclusion and remediation. Of these, contamination exclusion is typically the least costly and should always be the first—and sometimes only—measure taken. Improvements to contamination removal capabilities should be considered when exclusion measures prove inadequate.

Contamination exclusion

Preventing contamination in lubricated equipment starts with new oil. For several reasons, new oil from drums or bulk deliveries usually contains anywhere from 2 to 20 times the amount of particles that is acceptable for most lubricated equipment. This is not an indictment of lubricant suppliers, but a fact that must be addressed before cleanliness targets in machinery can be met.

In general, Potteiger says, it’s good practice to maintain the cleanliness of new oil at least two ISO codes cleaner than the targets for in-service oil. This will allow modest amounts of contamination to be introduced during transfer and application while still meeting the targets. Unfortunately, typical handling methods will add a lot more than a modest amount of contamination. Thus, for the average plant, lubricant-handling methods and equipment will need to be revised and upgraded to ensure oil cleanliness.

For small sumps that are filled from oil-cans, transfer containers should be made of plastic, sealed, marked for product type and maintained in a clean state. The use of funnels should be avoided when possible and separate handling equipment should be maintained for different lubricants. The simplest and most effective way to ensure that new oil additions are clean is to simply filter it as it is applied using portable filtration equipment. To do this, the reservoirs must be fitted with the proper fittings to effectively attach the transfer equipment.

Another effective and essential technique for preventing contamination is to stop airborne contaminants from entering machine reservoirs during service. Most reservoirs exchange air with the ambient environment regularly, and if that air is not filtered it can be a major source of contamination for both particles and moisture. “The good news,” Potteiger says, “is that this is one of the easiest problems to address through good headspace management.”

Headspace management is the process of managing the condition of the air that enters a sump when oil level is lowered or air pressure drops when the temperature goes down. Replacing typical OEM breathers with high-quality desiccant breathers will strip particles and moisture from the air as it enters the sump to a point where contamination is negligible. Other methods include purging reservoirs with clean, dry air or nitrogen to maintain positive pressure in the headspace, or using expansion chambers that effectively capture and re-circulate the air in the headspace.

For many common applications, such as small gearboxes and process pumps, contamination exclusion is the only practical approach. This makes good application practices and headspace management all the more crucial.

Contamination removal

Sometimes contamination exclusion is not enough. High ingression rates and/or sensitivity to contamination in some machines like hydraulics and those with circulating lube systems require improvements in contamination-removal capabilities as well. “When this is necessary,” Potteiger says, “the first step is to review existing filtration to see if the filters can be upgraded in terms of pore size, capture-efficiency or other factor.” If this is not the case, or if filter upgrades don’t achieve the desired results, offline filtration may be the best option.

Offline filtration systems, commonly referred to as kidney loops, offer several advantages over active filters in the oil-circulation system. Offline filtration is cost-effective because the kidney loop functions independently and is not bound by the flow rate and pressure requirements of the active circulating system. These systems also allow the use of alternative filter media and types such as depth media, electro-static, water-stripping and others that can remove more than just hard particles.

For critical applications where moisture contamination cannot be prevented, water-removal options include vacuum dehydrators, centrifuges, coalescing filters and water-absorbing filters. Vacuum dehydrators in particular are extremely effective at removing water from lube systems to the point that its presence is insignificant. Additionally, most vac systems include high-efficiency mechanical filters to remove particles, which makes them an excellent choice for contamination removal in any application where the cost can be justified.

Condition monitoring

Although most plants use oil analysis in some fashion, Potteiger believes few reap its full benefit. He views effective oil analysis as “the perfect condition-monitoring technology for proactive maintenance” because it can positively identify and quantify the top three root causes of machine failure: particle contamination, moisture contamination and use of the wrong (or degraded) lubricant.

Oil analysis is not difficult, Potteiger says. “Even a novice can easily learn to use viscosity and elemental analysis to verify oil for use in a machine.” Tests such as acid number, FTIR and QSA can be used to determine if the oil is suitable for use or has degraded, while particle counts and moisture concentrations require no deciphering at all. “Good oil analysis,” he continues, “depends on good oil-sampling practices, data analysis and data management, and with the proper education all of these things can be easily achieved.”

Summary

Potteiger sums up precision lubrication as a fundamental component of any good reliability program. Although it can take time to transform an average program into a great one, he reminds end-users that the fundamentals are simple: “Use the right lubricant, in the right amount, at the right frequency, maintain the lubricant’s condition with aggressive contamination control and verify condition with effective oil analysis.”

Jarrod Potteiger, Sr., is Technical Consultant/Manager–Training Services for Des-Case Corp. (descase.com).

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8:41 pm
December 14, 2014
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The State of the Lubrication Nation

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While our in-depth study of lubrication practices in North American industries provides some good news, it also reveals much room for improvement.

Lubrication plays a significant role in the success of any industrial plant or facility that operates moving equipment. With the “wheels of industry” literally relying on lubricant film mere microns in thickness, it is essential to recognize the need for good lubrication practice and implement a quality lubrication-management program.

As noted this month in the “From Our Perspective” column, thanks to studies performed by the Massachusetts Institute of Technology’s (MIT) Dr. Ernest Rabinowicz, we know that up to 70% of all moving equipment failures (loss of bearing surface usefulness) are caused by mechanical wear and corrosion, which can be directly and/or indirectly attributed to ineffective lubrication practices. Both of these practices, we also know, are entirely preventable with Good Lubrication Practices (GLP).

In practical terms, the impact of lubrication is astounding. GLP translates into asset availability, reliability, uptime, throughput, energy savings, carbon footprint reduction and profit. The Rabinowicz law states that “every year, 6% of the Gross Domestic Product (GDP) is lost through mechanical wear.” Applying Rabinowicz’s law to the 2014 estimated third-quarter U.S. GDP of $17.5 trillion, mechanical wear losses could amount to more than $1 trillion this year!

Determining North America’s ‘State of Lubrication’

To benchmark the current state of lubrication in North America, compared to accepted industry lubrication best practices, we created a comprehensive 37-question “State of the Nation’s Lubrication Practices” study and invited Lubrication Technology’s virtual subscribers to respond. To date, we have received 112 complete responses to this detailed survey, all from North America-based lubrication professionals.

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As depicted in Fig. 1, all major Industry types are represented, with Manufacturing as the largest sector at 32%. This is followed by the combined Natural Resources sector at 18% and the Automotive sector at 9%. The combined Food and Drug sector make up an additional 9%, with the Facility Management sector next at 8% and residual industries (the Other/Fleet sector) making up the final 24%.

Scorecard

The answers to all 37 questions were tabulated and averaged for all industry type sectors collectively, and for each specific industry sector, and scored out of 100. Table I shows how the nation scored on its lubrication practices.

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At an overall score of 43, these North American industry sectors have much room to improve on their lubrication practices. By a significant margin, the Natural Resource sector, with a score of 54%, leads the way. The good news is that both the individual answers and score levels demonstrate that lubrication awareness has been established.

System Review (Fig. 2)

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Individual questions in the survey are grouped into six lubrication-management program elements to enable the reader to understand specific areas requiring improvement. These elements are: System Review, Lubrication Personnel, Work Management, Contamination Control, Application Engineering and Safety. The first, System Review, asks if the company has had its lubrication practices professionally audited in the last three years. Professional audits open lubrication methods, processes and procedures to review by an independent resource skilled in developing best-practice lubrication programs so a customized improvement action plan can be developed.

Figure 2 shows that only 21% all sectors had been audited in the last three years. The most-audited sectors seem to be Automotive and Natural Resources, with 30% of both groups having been audited. The least audited is the Other sector, at 11%.

Another System Review component is the professional lubricant-consolidation exercise/program in which all lubricants on site are documented and analyzed to determine their necessity. This exercise is designed to consolidate and minimize the number of required lubricant SKUs, thereby reducing carrying and purchase costs, storage real estate, and the chance of causing lubricant cross-contamination through use of the wrong lubricant. This usually occurs just after or as part of the audit and, in this case, figures came out the same as those who say they were recently audited, with just 21% of all sectors performing a lubricant-consolidation exercise.

Lubrication Personnel (Fig. 3)

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Only 28% of all sectors combined use dedicated lubrication personnel, and only 12% of all sectors combined use only professionally certified (by ICML, STLE or ISO) lubrication personnel to administer their programs. Again, the Resources sector leads with 30% of this group using only professionally certified lubrication personnel. The Facilities sector comes in second with 20%. Manufacturing ranks the lowest: Only 1% of this sector’s lubrication personnel are professionally certified.

Certified and dedicated lubrication personnel appear to have made a difference with the Resource sector’s overall results.

Work Management (Fig. 4)

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Surprisingly, only 39% of respondents say they report all lubrication-related instances of machine failure or downtime. This may explain why only 42% of lubrication work is formally managed and tracked in a computerized maintenance management system (CMMS) on a work order and, of those, only 28% are specifically typed (designated) as lubrication work orders for reporting purposes.

Lubrication work orders are only effective if the work actually gets scheduled and completed in a timely manner. Only 28% of all respondents say they complete their lubrication work within 48 hours of WO issue and 29% of respondents review their lubrication PMs for task and schedule effectiveness on an annual basis.

Standard Operating Procedures (SOPs), designed to promote work consistency, are in use across all sectors for lubricants. According to the survey, SOPs are used at receiving by 42%; for manual bearing lubrication by 31%; for rotating lubricant stocks by 30%; and are used when taking oil samples for testing purposes by 26%. Again, the Resource sector is the predominant user of SOPs.

Oil analysis is used by 30% of respondents to determine oil-change intervals based on oil condition, and 43% say they perform regular quarterly (or less) cleaning and system checks on their automated lubricant-delivery systems.

Contamination Control (Fig. 5)

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Contamination control is arguably one the most critical aspects of lubrication management. Water, dirt and air all play their part in contaminating and destroying a bearing surface area and, unfortunately, much of it is introduced during the maintenance process.

From new, oil is relatively dirty and must be received correctly and filtered prior to use. Only 22% of all sectors have a lubricant cleanliness agreement with their oil suppliers. More than half—53%—say they do NOT reseal their bulk containers once opened to draw lubricant, and only 22% pre-filter their bulk oil prior to use. There are major opportunities for improvement in this area.

The better news is that 51% of all sectors use dedicated transfer equipment to eliminate cross contamination of lubricants, and 55% of all sectors use transfer equipment with closeable lids and spouts. It was great to see that 75% of all sectors store their lubricants in dedicated areas protected from the outside elements, and encouraging to see 61% of respondents always change/clean their filters when an oil change is performed.

Application Engineering (Fig. 6)

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A crucial part of GLP is documenting all bearing-point locations and types, so their lubricant requirements can be calculated for application purposes and to help avoid over-lubrication of bearing(s).

Although a crucial part of the lubrication program, the process of locating lubrication points and identifying lubrication types is performed by only 36% of respondents. The Manufacturing sector takes the lead here with 57%, and the Automotive and Resource sectors are right behind with 55% and 53%, respectively. Unfortunately, only 45% of respondents say they have schematics or drawings for their lube systems, and only 9% have lubricant requirement sheets for every bearing in the plant.

The ramifications of the above figures are reflected in the 60% of respondents who say they experience grease leakage from bearings on the floor, and the 41% who experience noisy bearings, hallmarks of ineffective lubrication practices.

There appears to still be a lot of manual greasing performed, yet only 41% of respondents use only one grease-gun type in their plant to eliminate the delivery and pressure issues that arise when different grease-gun types are used. Furthermore, only 6% of respondents measure and label their grease-gun output in cc/cu.in to enable engineered delivery to the bearing point, which is stated on only 20% of all greasing work orders.

Safety (Fig. 7)

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Almost every survey respondent indicated that his or her company is concerned about workforce safety. For example, 90% say they have easy access to lubricant Material Safety Data Sheets (MSDS). Additionally, 87% of all sectors operate a formal spill program, and 76% operating a formal waste-lubricant program. This is good news for personal safety and the environment!

Follow-up

Many of our study’s respondents are aware of the elements required to achieve a successful best-practice lubrication-management program and reap the benefits such programs offer and deliver. In upcoming issues of Lubrication Technology, we will address these issues in greater depth and discuss how to build on the foundation that many readers may already have in place at their facilities. The goal, regardless of sector, is to move all industries toward GLP.

Contributing Editor Ken Bannister of ENGTECH Industries, Inc., is a Lubrication Management Specialist and author of Lubrication for Industry (Industrial Press), and the 28th Edition Machinery’s Handbook Lubrication section (Industrial Press). He can be reached at 519-469 9173 or kbannister@engtechindustries.com.

1681

7:37 pm
December 1, 2014
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Lubrication Checkup: Grease Delivery Lines

1014lubecheckupBy Dr. Lube, aka Ken Bannister

Symptom:

“Recent fork-lift damage to one of our machines affected several steel grease-delivery lines connected to one of the Trabon automatic-greasing system’s lube blocks. Can I rely on the lube pump to pre-fill the replacement lines?”

Diagnosis:

A typical Trabon centralized grease-lubrication system consists of a pump assembly connected to a number of progressive divider distribution blocks. Each block has one line in and numerous lines out, connected to either a secondary distribution block or direct to the lube points. Each discharge point on a block could be feeding a different size bearing requiring differing amounts of grease. Therefore, the system and blocks must be custom engineered and built prior to assembly on the machine, and all lines filled prior to use. When a charge of grease is pumped into the block, the pistons actuate progressively, one after another, as the lubricant moves through the porting in the block and the correct amount is delivered to each bearing point.

Prescription:

Remember that you are dealing with a hydraulic system. Its lines must be pre-filled prior to startup so that small, apportioned amounts of grease discharged at the block can simultaneously hydraulically push an equal amount of grease at the line end into the bearing. Using the lube pump to fill lines will take a very long time due to the apportioning aspect of the system. In the process, some bearings could fail as a result of lube starvation.

All block discharge points have the ability to be piped into the side of the block (the most common arrangement) or into the front. Both discharge exits are connected, and the unused one will be plugged. Simply undo this plug and screw in a regular grease nipple. Next, undo the corresponding end of the grease line at the bearing point, connect a grease gun and hand-fill the line.

Once grease appears at the bearing-point end, reconnect the line, take out the grease nipple and re-plug the block. Repeat for all delivery lines and you are good to go! MT

Ken Bannister of Engtech Industries, Inc., is a Lubrication Management Specialist and author of Lubrication for Industry (Industrial Press), and the Lubrication section of the 28th Edition Machinery’s Handbook (Industrial Press). For in-house ICML lubrication-certification training, contact him at 519-469-9173 or kbannister@engtechindustries.com.

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