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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.

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  535 Hits

High speed sliding behavior of polymer coatings

WHY

Nowadays polymer based coatings are applied in all walks of life, due to their excellent corrosion resistance, low friction and cost, good surface finish, molding ability and low density. However, one of the main issue of these coatings is their relatively poor performance in terms of wear. Especially, when sliding under high speeds, frictional heating can lead to a softening of the coating and accelerate the wearing-off process. Evaluating the high speed sliding performance of polymer coatings is a key issue in many applications.     

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  532 Hits

How can we test the performance of cutting fluids for aluminum alloys?

WHY

Nowadays there is a great demand to use lightweight materials, such as aluminium alloys. One of their application possibilities is in the forming industry. In such demanding applications the use of a cutting fluid is essential to lubricate cutting edge and cool down the workpiece. Until now, to evaluate the efficiency of cutting fluids, ASTM D3233 tests on a Falex Pin-and-Vee Block tester were performed. However, this procedure was developed on hard tool steels and thus it is not appropriate for soft materials, such as aluminum alloys. In this application study and a modification of this procedure is proposed for testing of cutting fluids for soft materials and alloys.          

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  510 Hits

Friction measurements on complex shapes

 

Or download the pdf direct here

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  463 Hits

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.

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  459 Hits

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.

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  452 Hits

Friction modifiers put to the test. Can we influence friction?

WHY

In the effort to reduce CO2 exhaust, an important approach is to reduce friction in the engine.  One part of the mix of options are ‘friction modifying additives’, such as the well-known GMO, which are known to reduce friction by 5, 10 or 20%. However, the difficult task is to prove the effect of friction modifiers in the engine, since existing engine tests measure the interaction of all sliding and moving components, as well as lubricant viscosity and other effects. In order to isolate and evaluate the efficiency of friction modifiers, a precision frictional approach is required. 

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Cost efficient data collection for statistical analysis of wear - TRL 6

WHY

 One of the most difficult industrial issues related to tribology is the prediction of long term wear or material durability.  In many components and products, materials with or without lubrication are used to reduce wear and maintain functionality of the component.  Required ‘wear life’ may be thousands of hours.  Contrary to the determination of a ‘coefficient of friction’ – which can be done in a few hours, the determination of wear and wear rate under realistic conditions is a long term test. The challenge is twofold : perform low wear rate experiments with many repeats at an economically acceptable cost.  The only way to do this is by a multistation approach (performing many wear experiments simultaneously). 

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  353 Hits

High temperature sliding wear testing of materials

WHY

High temperature tribological testing often requires the development of complex mechanical setups, that should meet rigorous standards and specific performance metrics. Thus, the development of a state-of-the-art experimental setup to study the reciprocating sliding behaviour of various bulk and coated materials at temperatures that can reach up to 1000 °C is needed, especially for the evaluation of high temperature materials for aeronautical applications.

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  329 Hits

Seizure or galling resistance of materials at high speeds

WHY

In reality, due to a misalignment, vibrations or other reasons high speed pump rotors can come in contact with the stator, leading to a catastrophic failure.  This failure is a result of severe shearing of the contacting surfaces. However, the existing ASTM Galling method (G 196), is performed at very high pressures and very low speeds, and does not simulate the “actual” conditions met at high speeds.

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  304 Hits