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Application Note: AN6072

BLOCK ON RING TEST FOR OIL, GREASE
TIMKEN, OK, EP, FRICTION WEAR STUDIES
INLINE TORQUE, LIQUID RECIRCULATION, HIGH TORQUE

INTRODUCTION


The MFT5000 is a versatile mechanical property tester capable of simulating a vast number of tribology and wear tests on same platform. This application note shows how the MFT5000 can be used to study grease/oil for EP and wear tests using its block on ring module. Using this module, the MFT Platform can perform several ASTM tests such as ASTM D2981, D3704, G77, G176, D2509, 2782, Timken Ok Load test and several customized tests

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MATERIAL & METHOD

Oil or grease is placed inside the liquid container with attached heating chamber. A typical test is set up for up to 50ml lubricant with available options to test up to 1 Gallon lubricant. There are provisions available to recirculate lubricant (oil or grease) at a predetermined flow rate. The block corresponding to the referred standard is mounted on the self levelling upper holder to create a conformal contact between the upper and lower sample.



Wear Test - This method covers the determination of the friction and wear characteristics of greases or oil in sliding applications. Depending on the application and test requirements, the samples can be submerged, or the lubricant can be circulated using pumps or grease dispensers at pre-determined flow rates. The test can also be used to evaluate tribological and wear properties for solid lubricants and coatings. The tests can be easily configured by defining the temperature (up to 500C), loading rate, test load (up to 10,000N) and rotation speed (up to 5000 rpm). The rotating shaft is supported from both ends to prevent bending under high loads.





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EP Test - This method covers the determination of the extreme pressure (EP) characteristics of oil or greases in sliding applications. Load is increased in step or linear mode until there is seizure or sudden increase of coefficient of friction during the test. This method is commonly used in Timken OK test for grease and lubricants (ASTM D2509 and ASTM D2782). The wear on the sample is evaluated to determine pass/fail criteria for the lubricant at the load being tested. 

Custom Tests- Block on ring module is a highly versatile module and can be used to perform many customized tests such as oscillating tests, where the rings are oscillated clockwise and counter clockwise to a pre-determined angle or number of rotations. These tests are frequently performed to evaluate the performance of solid lubricants, coatings or surface texture on bearings and in applications where there is frequent change in direction or limited motion between the two counter parts. Customizable nature of block on ring modules allows real components including shafts, bearings and their counter parts to be mounted without much modifications. 
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ANALYSIS

Figure shows the comparison of different lubricants as tested using the block on ring module on a HRC30 block against a Timken ring, under constant load (1500N) and velocity (1500 rpm) at 200C. 
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Figure shows the EP wear test (modified Timken OK test conditions) for two different lubricants on the block on ring module. The test is stopped automatically when the friction force, inline torque or coefficient of friction increases drastically showing onset of failure. The test was set up to run for 90s, at 2700N, 1150 RPM at room temperature. The Sample 1 failed with in 30s, while the Sample 2 could run for the full duration of the test. The test for Sample 1 was stopped automatically when the torque increased drastically.
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CONCLUSION

MFT5000 block on ring module is an excellent option to run tests in block on ring mode. The load can be applied up to 10,000N with a precise temperature control and monitoring. Several ASTM and customized tests can be carried out on the same platform by adjusting the volume and flow rate of lubricant, loading rate, applied load, speed of rotation and test temperature. Several customized tests can also be performed on this module including testing real components. This module is useful to characterize tribological properties of additives, grease, oils, coatings, solid lubricants, bearings, shafts etc.  

REFERENCES & KEYWORDS

ASTM D2981, D3704, G77, G176, D2509, 2782, Timken OK

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