Application Examples

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Compressor fluids under pressure : unexpected effects

WHY ? : Air conditioner compressor fluids have to prevent friction and wear under elevated gas pressure.  Standard Pin&Vee Block tests with gas 'bubbling' through the lubricant do not correlate with field behaviour, especially with CO2 as the cooling medium.  Another simulation with pressurized gas is needed.  We selected the Falex Block on Ring configuration, as it also recreates the line contacts and is able to work at higher speed than the Pin&Vee block machine.

HOW ? : Our Falex Block on Ring machine allows pressurizing the lubricant chamber with a gas, up to 10 bar.  Standard block-on-ring tests are done with and without pressure on the dissolved gas.  Tests with increasing contact loads (EP) and tests with constant load (Anti-wear) are done.

 b2ap3_small_BlockOnRing Applications  b2ap3_small_BlockOnRingConfigs Applications

 

RESULT :

- A sudden loss of lubricity in the CO2 pressurized oil bath can be measured.  Block temperature increases suddenly at 70°C, while lubricant temperature decreases, which indicates that CO2 bubbles are forming in the interface between block and ring. This phenomenon is only seen when the gas is dissolved under pressure in the lubricant.

b2ap3_thumbnail_Divergence Applications

 

- This leads to poor lubrication and increased wear.  Thanks to right additives, this bifurcation can be eliminated and wear prevention can be significantly improved under pressurized conditions.

b2ap3_thumbnail_Results Applications

 

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Thermosetting polymers for high speed bearings : linking friction and heat

WHY ?  : Polymeric materials are used more and more as cage material for light weight bearing applications, but thermoplastic materials suffer from PV limits.  At high speeds, the polymer may melt easily under light loads.  Thermoset resins don't have this limit, but may still disintegrate under higher temperatures.  In this method, we can apply high speeds and variable loads, to explore the limits of thermosets.

HOW ? : The Falex Block-on-Ring tester has a simplified journal bearing geometry and consists of a stationary block loaded against a rotating or oscillating ring. A stable line contact is created, where speed, load, temperature, angle of oscillation, specimen material and finish can be varied. For this work, high speeds are of interest. Friction forces are low, but the accumulation of temperature is giving useful information about the amount of friction dissipated in the contact, and whether the materials can withstand these conditions.  Comparative testing can show the advantages of thermosets over thermoplastics for high speed applications.

b2ap3_thumbnail_Falex-BOR Falex Block on Ring - Application examples | FACTLABS.ORG 

 

RESULT :

- Ranking of different polymeric materials under experimental conditions that simulate the actual application is possible.

- The evolution of friction can be linked to the temperature, applied load and sliding velocity.

 

b2ap3_thumbnail_COF-vs-T_material-A Falex Block on Ring - Application examples | FACTLABS.ORG b2ap3_thumbnail_BOR_T_comparison Falex Block on Ring - Application examples | FACTLABS.ORG

 

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