Lubricant tribology-What Are Lubricants? – About Tribology

Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction , lubrication and wear. Tribology is highly interdisciplinary. It draws on many academic fields, including physics , chemistry , materials science , mathematics , biology and engineering. People who work in the field of tribology are referred to as tribologists.

Lubricant tribology

Lubricant tribology

Related Lubricant tribology. Speed Factor and Bearing Design Speed Lubricnt another parameter of the tribological system that requires further detailed analysis. In addition to choosing lubricants based on chemistry, the tribo-engineer also needs to analyze the application based on the tribological system, which includes an analysis on speed factors, elastohydrodynamic EHD lubrication, bearing-life calculations, extreme-pressure lubrication, emergency lubrication and other Lubricant tribology application requirements. Although not universally applicable, these simple statements hold for a surprisingly wide range of systems. The importance of tribology has Hydrocortisone while pregnant increased over time.

Hot teen photots. Tribological System

Hribology would recommend this class to any of my colleagues in the tribological area. These will be reviewed where necessary to provide the required background. Lubricant tribology also coordinated several international collaborations on standards activities. Search form Search. Prior to joining MiTi he was associated with the National Lubricant tribology of Standards and Technologywhere he served in several capacities including Leader of the Ceramic Manufacturing Group. Our expertise allows us to determine lubricant and chemical effects in Lubricant tribology systems, to aid the development of new products for the field. Friction is not considered a tribologg force. They trubology how to extract the essence, how to structure, and how to make sense of the multitude of information from a complex field. The program is intended for two kinds of participants: those who are active or intend to be active in research on some aspect of tribology, and those who have encountered practical friction and wear problems and wish to learn novel methods of solving them. When two rough surfaces slide against each other or roll the asperities of Lubricant tribology surfaces come close to each other and interlock, adhere and generate friction. It called for the establishment of Institutes of Tribology, along with the publication of a handbook on tribo-design hribology engineering. Full-film lubrication exists in Prowl tgp forms: hydrodynamic and elastohydrodynamic. My management Lubricant tribology understand tribolgy this class was very valuable.

University of Dayton , United States of America.

  • Ingram Tribology provides specialist knowledge of lubricant tribology and testing.
  • Tribology is the study of the science and technology of interacting surfaces in relative motion and encompasses the study and application of friction, wear, lubrication and related design aspects.
  • For a vast majority of the surfaces encountered in nature and used in industry, the source of friction is the imperfections of the surfaces.

In the past, the lubrication requirements for a specific application could be satisfied by using general-purpose lubricants. Lubricant selection was typically based on experience and knowledge. Today, this approach is no longer viable due to the requirements of the current demanding environments to run faster, longer and hotter.

Today's lubricants must satisfy extreme requirements that are specific to each application. Tribology - the study of friction, lubrication and wear - has become the basis for selecting lubricants.

The lubrication requirements for a given application can be identified by examining the effects of tribological system parameters on lubricant chemistry. Figure 1. Before the proper lubricant can be selected, the tribological system must be identified. This system includes the type of motion, speed, temperatures, load and the operating environment.

Once these system parameters are identified, the lubrication engineer or tribo-engineer can utilize different lubricant chemistries to select a lubricant that will optimize the performance of the application. In addition, the lubrication engineer must analyze the application based on the identified tribological system. This analysis includes elements such as speed factors, elastohydrodynamic EHD lubrication, bearing-life calculations, extreme-pressure lubrication, emergency lubrication and various special application requirements.

The first parameter of the tribological system involves the type of motion. The motion may be sliding, which would require the hydrodynamic lubrication theory for its analysis, or rolling, in which case EHD lubrication theory would be applied. Combined sliding and rolling is also a possible form of motion in certain rolling-element bearings including the tapered roller bearing.

Sliding in the rib area can occur in this bearing, but the rolling elements roll on the raceway surfaces. Lubricant protection of these types of motion can be optimized with specific chemistries. Speed is the second parameter on the tribological system.

Speed of roller element bearings can be broken into the general ranges: fast, moderate and slow. Specific ranges for each of these speed categories can be set by using the speed factor, as defined in Equation The third tribological parameter is temperature.

All lubricants have specific temperature ranges for optimal performance. Knowing the temperature of the tribological system enables the engineer to select a lubricant that will provide optimum operating life and performance at the application temperature. Figure 3. Load, the fourth parameter, is an important factor affecting the lubricant requirement.

A light load may indicate the application is sensitive to frictional torque, and therefore a lubricant would have to be selected to minimize the fluid friction while still providing protection from metal-to-metal friction.

On the opposite end is a heavily loaded application, which could require specific additives to help protect from pitting, galling and extreme wear. The last parameter of the tribological system is the application's operating environment.

If the environment includes moisture or water, the lubricant must provide good anticorrosion properties as well as resistance to water washout or contamination. If the application operates in a vacuum or partial vacuum, the atmospheric pressure of the application must be within the operational limits of the lubricant and above its vapor pressure at the operating temperature.

If the application requires the presence of certain chemical liquids or vapors, the selected lubricant must be resistant to these chemicals. Even an ideal environment, such as a computer room or clean-room processing facility, could have specific requirements for noise-reducing lubricants in rolling-element or instrument bearings.

The five parameters of the tribological system must be taken into consideration and analyzed for the best lubricant to be selected for the application.

However, the information obtained by defining the tribological system parameters also provides data for further in-depth technical analysis. An important type of analysis involves the lubrication theory for rolling-element bearings.

Equation 2. Lubrication engineers use the EHD lubrication theory to select the proper viscosity of the lubricant. Each of the variables in Equation 2 has a specific impact on the ultimate film thickness. One of the lubrication engineer's primary interests is how a change in a specific variable will affect the magnitude of the film thickness. From Equation 2, it can be determined that if the pressure-viscosity coefficient a is doubled, there is an increase in the film thickness by 51 percent.

Knowing the pressure-viscosity coefficient of the different lubricant chemistries, the lubrication engineer can alter the film thickness by changing the lubricant chemistry. The remaining physical characteristics of the lubricant are not changed. Another lubricant-related variable in Equation 2 is the dynamic viscosity, h. The dynamic viscosity can be directly related to the kinematic viscosity , and if it is doubled, will increase film thickness by 62 percent.

By doubling the velocity of the roller bearing, the film thickness of the lubricant can again be increased by 62 percent. The lubrication engineer has no control over the speed of the application, but knowing how the speed affects the film thickness is important to the selection of a lubricant when the application has variable-speed capability. Additional variables have a lesser impact on the film thickness of the lubricant.

Figure 4. While the information in Equation 2 is important to the lubricant selection criteria, the EHD film thickness is not used directly because in reality, surfaces are not perfectly smooth. It is at this point that the transition from boundary lubrication into the mixed lubrication occurs.

Lambda values greater than 4 are possible and sometimes desirable, particularly where variable speeds and or shock loading is present. However as l increases beyond 4, the internal fluid friction may increase and generate excessive heating and energy consumption depending upon the relative bearing speed and oil viscosity. Research sponsored by the bearing manufacturers has made it possible to calculate the minimum required viscosity of the lubricant V1 to obtain separation of the moving surfaces.

The nomograph in Figure 1 can be used to determine the value of V1 from the mean bearing diameter, dm, and the operating speed, n. For example, enter the bottom of the chart with the average diameter of the rolling-element bearing mm , then proceed vertically to the speed of the bearing 2, rpm.

Knowing the required minimum viscosity, V1, at operating temperature, the lubrication engineer can then select the appropriate lubricant based on the specific viscosity, k, which is defined as the ratio of the actual viscosity, V, of the selected lubricant to the required minimum viscosity, V1. Given this information, the engineer will attempt to select a lubricant to meet the full fluid film lubrication regime for the application.

If this is not possible, then the next available option is to select a lubricant that provides the best protection to the application.

Figure 2 shows how k relates to both lubricant selection and expected bearing life. At k values below 1, it is generally accepted that EP additives will be required to mitigate the effects of boundary lubrication conditions. At k values above 1, it is in fact possible to exceed the L value of the bearings, perhaps by as much as 2.

As k approaches 4, the bearing life approaches a maximum all else being equal while k values above 4 may cause increase fluid friction, viscous drag, ball skidding and other undesirable effects. If the application is operating in a lubrication regime that approaches full fluid film lubrication, these extreme-pressure additives can be eliminated from the lubricant.

The EHD theory is a valuable tool in guiding the lubrication engineer toward selecting the proper lubricant. If the lubrication engineer uses the specific viscosity as part of the selection criteria, the assumptions used in the analysis must be taken into consideration, along with the controllable variables.

Two specific points should be considered:. Calculation of film thickness h0 , specific film thickness l , and the chart used to determine required viscosity V1 are all based on the pressure-viscosity coefficient a of mineral oil.

Figure 3 shows the pressure-viscosity coefficient for mineral oil and four other oils over the pressure range zero to 2, bar. The oil is considered to be the only lubricating component of the lubricant. In a grease, it is believed that the thickener system does not contribute to the lubricating film thickness. However, the thickener system can have a significant effect on film thickness.

Figure 4 documents research identifying the effect of a grease thickener system on the actual film thickness. While a clay-thickened grease reduces the film thickness, it does have the benefit of reducing frictional torque in the bearing. The opposite effect is observed for grease thickened with a barium-complex soap.

Speed is another parameter of the tribological system that requires further detailed analysis. The calculated speed factor for a rolling-element bearing, which is defined as the product of bearing speed n and mean bearing diameter dm , is not consistent for all bearings with the same dimensions and speed.

The lubrication engineer must apply a correction to the calculated speed factor, depending on the bearing design. Analysis of the tribological system for a given application is essential to the selection of the appropriate lubricant. Many applications have special requirements that go beyond the tribological system that must be taken into consideration.

Some applications are limited to oils, while others require a grease. Applications that involve the use of sintered bearings or special sealing arrangements will require additional analysis. Material compatibility is another important issue. Multipurpose lubricants cannot provide satisfactory service in current demanding environments.

Lubricant performance must be optimized to meet the increasing demands of modern industry. The first step in selecting the best lubricant for a given application is to define the tribological system. With a fully defined tribological system in place, the next step is theoretical analysis.

Selection of a lubricant based on EHD lubrication analysis or analysis of any other discrete parameter is inappropriate, because such analyses focus only on a subset of the tribological system. Toggle navigation Toggle search. Magazine Subscribe Today! Current Issue Archive Advertise.

Minimum Allowable Viscosity for Lubrication of Rolling-element Bearings at Operating Temperature Tribological System Before the proper lubricant can be selected, the tribological system must be identified.

Type of Motion The first parameter of the tribological system involves the type of motion. Figure 2. Temperature The third tribological parameter is temperature. Pressure-viscosity Coefficients for Five Oils Over the Pressure Range 0 to 2, bar Load Load, the fourth parameter, is an important factor affecting the lubricant requirement.

Operating Environment The last parameter of the tribological system is the application's operating environment. Tribological Analysis Theories The five parameters of the tribological system must be taken into consideration and analyzed for the best lubricant to be selected for the application.

EHD Lubrication Theory An important type of analysis involves the lubrication theory for rolling-element bearings. Film Thickness and Frictional Torque for Base Oil and Five Greases as Functions of Bearing Speed While the information in Equation 2 is important to the lubricant selection criteria, the EHD film thickness is not used directly because in reality, surfaces are not perfectly smooth.

Based on the laws of viscous flow, Professor Osborne Reynolds developed the classical equation of thin film lubrication. It should be noted, that it is typically desired to have a sufficiently thick lubricant film, so that the surface are completely separated to reduce wear. The instructors delivered very nice and well prepared talks. Randall has published extensively in the field of surface mechanical properties testing, especially related to scratch adhesion testing, nanoindentation and tribology testing. This equation carries his name and forms a foundation of the lubrication theory. My management will understand that this class was very valuable.

Lubricant tribology

Lubricant tribology

Lubricant tribology

Lubricant tribology

Lubricant tribology

Lubricant tribology. Definition of Hydrodynamic Lubrication (HL)

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Tribology: the Key to Proper Lubricant Selection

The study of friction, wear, and lubrication is of enormous practical importance, because the function of many mechanical, electromechanical, and biological systems depends on the appropriate friction and wear values.

The potential savings offered by improved tribological knowledge are immense. For example, an undergraduate engineering student receives perhaps an hour of instruction in tribology. This program presents current insights into tribology, focusing on such fundamental concepts as surface energy, elastic and elastoplastic deformation, micro-fracture, and surface interactions at the micro- and nano-scale.

Special consideration is given to the application of fundamental knowledge to control friction and wear behavior through lubrication and the selection of materials and coatings in practical situations. After that date you may be placed on a waitlist. Courses with low enrollment may be cancelled up to 4 weeks before start date if sufficient enrollments are not met.

If you are able to access the online application form, then registration for that particular course is still open. The program is intended for two kinds of participants: those who are active or intend to be active in research on some aspect of tribology, and those who have encountered practical friction and wear problems and wish to learn novel methods of solving them.

The course requires at least a bachelor's degree in engineering or physical sciences, including basic courses in mathematics, applied mechanics, materials science, physics, and chemistry. Some lectures introduce advanced concepts in these areas and in physical chemistry and thermodynamics. These will be reviewed where necessary to provide the required background. Industrial experience is preferred. Each participant receives digital and hard copies of the course lectures. View Course Schedule pdf.

Class runs am - pm every day except Friday when it ends at noon, followed by a farewell lunch. Special events include: a networking reception Monday evening; a program dinner for course participants, their families, and faculty on Wednesday night; and a farewell lunch on Friday at noon. Evening activities and the lunch are included in tuition.

I expected it to be "in-the-clouds" mysterious as other triobologists I have come across have acted. I like the courage of the presenters defining what is known, what is estimated, and what is unknown. It has improved my view of tribology's legitimacy. I came back with a lot of ideas for the company and my testing design.

A chance to ask questions and get answers on specific topics of interest. The ability to converse with industry professionals regarding very specific areas of knowledge. I came to the class with a problem I needed to start on without knowing where to begin.

By day two of the class, I had a feasible idea and by day four I believe I have a solution to the problem. Now, I just need to prove my theory. My management will understand that this class was very valuable. The instructors delivered very nice and well prepared talks. I would recommend this class to any of my colleagues in the tribological area. I will be directly applying what I learned and use the handouts and textbooks as references for years to come.

Saka and Suh are very good instructors. They know how to extract the essence, how to structure, and how to make sense of the multitude of information from a complex field. The content was extensive and informative. The lecturers were impressive and highly knowledgeable in their fields.

The social events dinner and lunch were superb and provided for wonderful personal and technical exchanges with the attendees and lecturers. I found the dialogue and questions in the classroom to be very interesting and engaging. The classroom accommodations were good and the refreshments provided were of good quality. Suh in research on a variety of tribological problems and phenomena. Saka has co-authored over technical papers in tribology, mechanical behavior of materials, and manufacturing processes.

He holds seven U. Over the years he has supervised 30 bachelor's, master's and doctoral theses, and has been a committee member for a dozen doctoral theses.

He is also the Ralph E. He was the presidential appointee in charge of engineering at NSF He is the author of papers on the delamination theory of wear, genesis of friction, solution wear, and undulated surfaces. He has received nine honorary doctoral degrees from four continents.

MiTi , where he serves as Vice President for Biotechnology and leads efforts on implantable blood pumps. Prior to joining MiTi he was associated with the National Institute of Standards and Technology , where he served in several capacities including Leader of the Ceramic Manufacturing Group.

He directed research activities that ranged from characterization of ceramic powders to assessment of mechanical properties of advanced materials.

He also coordinated several international collaborations on standards activities. He served as chair of the Ceramic Machining Consortium that he established as a joint research program between NIST, industry, and academic organizations His research in tribology and machining of advanced materials is widely recognized in the scientific and engineering communities. He has edited several books and conference proceedings on machining and tribology of advanced materials.

He has been active in technical and administrative committees and boards in several engineering societies and has served in several advisory groups in the federal government and universities.

He was elected to chair the Gordon Research Conference on Tribology He is also active in local educational policy issues and served as President of Partnership for Educational Policy , a new organization formed to inform the public and policy makers on educational issues that have a wide reaching impact on K education. He was honored as the Community Hero by the Montgomery County Civic Federation for his contribution to local educational issues.

He holds three U. Nicholas X. This system has now been commercially available since He was responsible for after-sales service, technical documentation, installations, training, and contract testing laboratory service. He then joined Alemnis in as Vice President. Alemnis develops and manufactures mechanical testing instruments for small-scale testing, both in-situ and ex-situ.

Randall has published extensively in the field of surface mechanical properties testing, especially related to scratch adhesion testing, nanoindentation and tribology testing. Wedeven continued his research activities in tribology at the NASA Lewis Glenn Research Center for 14 years with a focus on gas turbine lubricant evaluation and performance mechanisms.

Wedeven holds two patents on vapor lubrication and a tribology test machine and process patent. Hodson Award. Wedeven has written three book chapters on tribology.

He is author of over 90 technical publications and teaches tribology classes for ABMA. We can also offer this course for groups of employees at your location. Please complete the Custom Programs request form for further details. Skip to main content. Search form Search. Jun 22, - Jun 26, Register for Updates.

Register now. Registration for this course has closed. Register for updates to receive news about this program. View Course Schedule pdf Class runs am - pm every day except Friday when it ends at noon, followed by a farewell lunch. Exceptional opportunity to learn from word-wide known tribologists. Nannaji Saka. Nam Pyo Suh.

Said Jahanmir. Lavern Vern D.

Lubricant tribology

Lubricant tribology

Lubricant tribology