It occurs when two solid surfaces slide over one another under pressure. Surface projections, or asperities, are deformed and eventually welded together by the high local pressure. In bearings and gears the metal surfaces are actually separated by lubricating oil or grease. As sliding continues, the lubricant is compromised and metal to metal contact occurs. The molecular bonds in the metal part are broken, producing surface cavities, projections, and abrasive particles, all of which contribute to abrasive wear. A fourth ball is placed in the instrument chuck and brought into contact with the three lower balls.
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Groshakar Results are reported in kilograms kg with a functional range from kg to kg. Maintenance Services and Products. Current Issue Archive Advertise. It was found that all three greases showed good mechanical shear stability, antiwear performance and extreme pressure characteristics consistent with the specifications to which x individual grease was designed.
The dilution in performance is again nearly equivalent to the level of contamination, that is a 20 2d reduction in the load wear index upon 20 percent contamination. The higher the number the greater load-carrying ability. Water washout ASTM test: Ideally, a supplier with an intensive research and development program is willing to perform tests before a lubrication change is implemented to protect machinery from failure or wear.
Changes in physical properties would be reflected by a softening or hardening of grease consistency, or decreased shear stability upon mechanical working and even reduction in thermal stability identified by awtm reduction in dropping point. The higher the L-M score, the more applications the grease will provide lube protection. The lower the percent change, the greater the mechanical stability of the grease. It is best to d increase the frequency and reduce the volume.
Determines the strenghth of the boundary film between metal surfaces that provides extended protection. Innovative data and testing tools aid the decision process through the analysis of two or more co-mingled greases. Based on this value, one can formulate greases with different levels of extreme pressure properties. A Testing Example An overview of a recently performed aviation grease study by Anderol demonstrates the necessity of proper grease testing within the actual manufacturing environment.
Make sure to use a valid business email address. In addition, because equipment users usually do not have the proper resources to perform testing themselves, it is the responsibility of the grease supplier to measure grease compatibility with dropping point, penetration and high-temperature performance test machines.
The lithium complex grease, sample No. Although these results do not necessarily correlate with real life applications, the method has become an industry standard in comparing EP, wear and frictional functionality. An aetm issue could be reflected in reduced lubricating performance due to the modified composition of the fluids and additives from intermixing. The final determination of compatibility comes with proper testing of greases in the application for key performance properties.
A critical part of this assessment is working with a lubricant supplier with the specific industry know-how, and the proper testing procedures in place to ensure maximum grease compatibility and performance, promoting business success and profitability.
Determines resistance qstm a lubricating grease to washout by water Result values and what they mean: Oxidation stability ASTM test: These tests can be conducted concurrently or sequentially with varying ratios for example, The answers are in a few ASTM test methods. The result is breakdown of grease, cold welding or galling. Seven tests for selecting the right d Seven tests for selecting the right grease Greases are used to overcome real-world problems presented by operating environments and operating conditions of mechanical equipment.
In addition, where possible the supplier should be present throughout a grease changeout to make sure the new grease runs correctly. What the test measures: Mud, water and steam can wash away grease, leaving metal unprotected. The supplier should also spend time with maintenance personnel to make sure they know what to look for going forward. Understanding compatibility and contamination is the first step to optimal grease performance, plant operations and return on investment.
Result values and what they mean: Click Here to see Tables 1 and 2. Results are reported as percentage with a functional range from 0.
Optimally, supplier testing will show low levels of contamination where xstm is not affected, making zstm transition to a new grease product quick and easy.
Wear scar properties and coefficient of d of a lubricating grease can also be determined using the 4 Ball Wear configuration. Relubricate frequently, taking care not to overlubricate, especially motors.
The purpose of this test is to determine the wear preventive characteristics of a lubricant. About the Author John Kurosky. At the conclusion of the test, the three wear scars are measured and the average is reported.
In some cases, performance properties of the mixed greases may be less than the lower performing grease, yet still meet customer specifications and requirements. The Leon-Maxwell number is an excellent method to quickly and accurately evaluate a grease protection potential and as an indication of a greases ast to be used in a wide variety of applications.
However, a true incompatibility situation may result when low-performing grease affects the performance of the higher performing grease, meaning another grease with more desirable intermixing attributes should be considered. Determines a greases ability to withstand repeated mechanical stress.
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Vilkis The equation normalizes the results and produces a value that can be used in the selection, application and consolidation process from typical to extreme environments. Advantages of Using Polyurea Grease. Current technology pinpoints assessment of dropping point, consistency after shearing conditions, and change after storage at extremely high temperatures as measurements providing the most information with the least resource expenditure. Simply put, all the grease samples were found to be compatible with one another. Tribological Testing by 4 Ball Methods The Best Gets Better: In the next issue, we will describe how wear scars from the various tribological tests are measured two dimensionally using optical microscopes and three dimensionally using profilometry. Determines resistance of lubricating greases to oxidation and helps determine shelf life of grease.
The lithium complex grease, sample No. If incompatibility occurs, failure would be found in any of the tests of a given specification requiring no other testing; however, a borderline compatible reading requires additional application testing for conformance to the extreme temperatures and excessive pressure conditions of a given grease application. Grease Sampling Methods Matter. Make sure to use a valid business email address. How do you know if the grease you are using is right to protect against harsh environments AND routine operating wear. Taking this precautionary measure assures reliability and performance of equipment.
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