Application Examples

for standardized tests, check 'our tools' page

Prescreening the ISO20763 & ASTM D7043 Vickers Vane Pump tests

WHY ? : the standard method for evaluating anti-wear of hydraulic fluids in a vane pump, is by the 100 hour ASTM or 250 hour ISO method, using a real Conestoga-built vane pump.  This method takes a long time to run, and requires a lot of fluid.  This makes it difficult to use the method for development or research.

Various lab or bench test methods have been evaluted as a prescreening method, but none of them have shown any satisfactory correlation with real pump wear, so far (as clearly proven by the review of G.E. Totten 1996, Prediction of Hydraulic Fluid Performance: Bench Test Modeling, Dr: George E. Totten, Union Carbide Corp. Roland J. Bishop, Jr., Union Carbide Corp. Gary H. Kling, Caterpillar Inc. Presented at the International Fluid Power Exposition@ and Technical Conference 23-25 April 1996).  Recent attempts to correlate an SRV based test have also failed the correlation test.

HOW ? : We have studied the wear mechanism that takes place in a vane pump, and with the help of some special test specimens - designed for the Falex Multispecimen machine - recreated the vane contact vs. ring conditions, and the pressure pulses created by the inlet and outlet ports.  By using these custom specimens and a recirculating oil system, we can run a wear test with similar test conditions, in 22 to 44 hours.  By careful experimental design, we can run the test without creating excessive heat or catastrophic failure, so we focus on simulating the normal working conditions of a vane pump.

 

 b2ap3_thumbnail_Falex-Vane-specimens Applications b2ap3_thumbnail_WorkingLimits Applications b2ap3_thumbnail_ComparisonWear Applications

RESULT : 

  • we can simulate the same wear mechanism as in the Vane pump test (and as in real vane pumps)
  • we can rank the wear rate of different hydraulic fluids, correlating with the wear rate ranking in the Vane pump test
  • we can monitor in situ the coefficient of friction and online wear, giving us more information about the mechanism and evolution during the test
  • we can avoid the excessive heating of the test specimens

 

Continue reading

Simulation of wear in roll-slip contacts

WHY ?  : The steering system of cars is based on a rack and pinion system. Over time, the metal on these gears wears out, resulting in a loose fitting. Some other applications also make use of a rack and pinion system to translate a rotary drive motion into a linear displacement.  The wear and tear of such systems occurs through a roll-slip mechanism. Therefore a tribological method needs to be developed to simulate such roll-slip contacts and their failure mechanisms.

HOW ?  : A modification on the Falex Multispecimen machine allows for a 2-rollers on disk geometry. During each turn these rollers rotate and slide simultaneously, simulating a roll-slip contact. The speed and load can be adjusted to achieve similar contact conditions as in the actual application. The contact can be either dry or lubricating, whereas the rollers and/or disks can be bare or coated materials. In this application series we investigated the use of coatings to decrease the friction and wear of the tribo-system, whereas the contamination of lubricant with hard particles (e.g. sand) was also taken into consideration.   

b2ap3_thumbnail_Falex-Multispecimen Falex Multispecimen - Application examples | FACTLABS.ORG 

 

RESULT :

- A roll-slip contact can be simulated by a Falex Multispecimen tester.

- Coatings can improve the wear resistance and frictional performance of roll-slip contacts.

- The presence of hard particles is a major risk for degrading the performance of a lubricant in roll-slip contacts.

b2ap3_thumbnail_Effect-of-coating-on-COF Falex Multispecimen - Application examples | FACTLABS.ORG

b2ap3_thumbnail_effect-of-sand-on-wear-evolution_roll-slip Falex Multispecimen - Application examples | FACTLABS.ORG b2ap3_thumbnail_effect-of-sand-on-roll-slip-wear Falex Multispecimen - Application examples | FACTLABS.ORG

 

Continue reading

Abrasion by powders during powder processing

WHY ?  : One issue in the pharmaceutical industry, is the abrasion of processing components for pressing the powders. The intensity of the abrasion phenomena strongly depends on the composition and size of the processed powders. Up to date there is no fixed procedure on how to evaluate such abrasion phenomena, in conditions that simulate the realistic process.

HOW ?  : A modification on the Falex Multispecimen machine was prepared to simulate powder pushing over a pressing disk. In the updated setup a knife - similar to the actual application - was attached to the machine. Powder is supplied and continuously refreshed from the center of the contact. This refreshment and distribution is essential to avoid attrition or poor repeatability.  After completion of a test, the wear mechanisms on both knife and disk are investigated by optical microscopy. Changes in the cutting tip were evaluated by comparing the tip angle before and after the tests with a confocal microscope. The wear damage was assessed by measuring the width of the scar of the knife before and after testing.

 

b2ap3_thumbnail_Falex-Multispecimen Falex Multispecimen - Application examples | FACTLABS.ORG 

 

RESULT :

- A methodology was developed to evaluate the abrasion of components used for powder processing in the pharmaceutical industry.

- The wear mechanisms were assessed and correlated to the one met in the actual application.

- The use of coatings to improve the abrasion resistance and lifetime such components was considered.

 b2ap3_thumbnail_wear-on-knife Falex Multispecimen - Application examples | FACTLABS.ORG

b2ap3_thumbnail_58HRC-beforetest-200-a Falex Multispecimen - Application examples | FACTLABS.ORG b2ap3_thumbnail_HSS_50_2 Falex Multispecimen - Application examples | FACTLABS.ORG

 

Continue reading
© 2017 Falex Application Center for industrial Tribology