Application Examples

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Tackiness of industrial greases : a quantitative method

WHY ?  : Lubricating greases are used in various industrial fields ranging from food, transportation, aeronautical, construction, mining and steel industry. The aim is to decrease frictional forces and to protect industrial components from wear and/or corrosion damage. Their performance depends on interaction properties like adherence to the substrate, cohesion or consistency, and tackiness. However, up to date there is no established quantitative methodology that can be easily applied to efficiently and accurately evaluate the adhesion and tackiness of a grease.

HOW ?  : A test procedure is established, based on approach-retraction curves, by using an upgraded TETRA Basalt-N2 micro-tribometer, with a Millinewton light load sensor. In this procedure a user selectable indenter body (ball, pin) gradually approaches the grease layer until they come into contact, then the indenter body keeps moving down until a pre-set contact load is reached. Then, the indenter body moves away from the greased substrate under well controlled conditions, until complete physical separation. During this approach-retraction cycle, the force on the load sensor is measured as a function of time and distance moved. This technique is the same as pull-off force experiments with an atomic force microscope for studying physical interactions.

b2ap3_thumbnail_PICTURE lubrication - Application examples | FACTLABS.ORG

RESULT  :

- The approach-retraction methodology combined with the Basalt-N2 high precision sensor provide a useful tool that is capable of evaluating the pull-off force and tackiness of greases under variable conditions, depending on the industrial application.

- The ranking of different greases at variable conditions is possible. This will allow developers and end-users to differentiate between available greases and select the one that fits better to an application, whereas grease producing companies can quantitatively evaluate the quality of their products more easily. 

b2ap3_thumbnail_tackiness-graph lubrication - Application examples | FACTLABS.ORG

b2ap3_thumbnail_effect-of-speed-on-pull-off-force lubrication - Application examples | FACTLABS.ORG b2ap3_thumbnail_Ranking-of-greases lubrication - Application examples | FACTLABS.ORG

 

 

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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. 

HOW ?  : The high precision tribometer Basalt-S2 was used. Applied loads and friction are measured with mN precision, using a ball-on-flat contact geometry. This creates realistic contact pressures.  Due to the high sensitivity of this tester, differences between the base oils and friction modifiers were successfully recorded.  

b2ap3_thumbnail_S2-machine lubrication - Application examples | FACTLABS.ORG 

 

RESULT :

- The effect of different modifiers can be separated by the precision microtribometer.

- Measurements are repeatable enough to draw significant conclusions.

- A ranking of base oils and oils containing friction modifiers is reached.

- A friction reduction of 10 to 18% in the moving contact is possible with the use of the right friction modifier.

b2ap3_thumbnail_Modifiers_COF-evolution lubrication - Application examples | FACTLABS.ORG

b2ap3_thumbnail_Modifiers_COF-comparison lubrication - Application examples | FACTLABS.ORG

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Testing of oils for the automotive industry

WHY ?  : A variety of oils for the automotive industry is available in the market. These oils have different composition, additives and can operate under different conditions (motion, load, speed and temperature). A method need to be used to prescreen the performance and endurance of these oils under different conditions, which are relevant to the automotive industry.    

HOW ?  : A TE-77 high frequency friction machine developed by Phoenix tribology, was used. This set-up alloys for a reciprocating motion under variable frequencies, loads, temperatures and/or displacements. During the test the friction, temperature of the bath and contact potential potential are continuously monitored and recorded. In this way variations in those parameters can be linked to changes in the oil (e.g. activation or depletion of additives), to surface changes (growth or removal of an oxide layer), to changes in the lubrication regime (in accordance with Stribeck curves) etc. After testing, the wear on both the plate and countermaterial are evaluated by optical and confocal microscopy.

 

b2ap3_thumbnail_TE-77 Applications  

 

RESULT :

- TE-77 is a versatile machine that can test the reciprocating sliding wear of oils.

- The evolution of the coefficient of friction can be linked to temperature changes.

- Different oils can be ranked under various loading, speed and temperature conditions.

- The presence of contaminants (particles) in the oil can have a significant effect in its performance.

b2ap3_thumbnail_TE77_effect-of-T-on-COF Applications b2ap3_thumbnail_TE77_effect-of-particles Applications

b2ap3_thumbnail_TE77_endurance-of-oils Applications

 

 

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How can we measure the friction on wiper blades ?

WHY ?  : Wiper blades are of great importance to the safety of the driver. In reality they can operate under different speeds (various scales in the car) or under different lubrication conditions (from dry to wet with thin or thick film of water). To simulate these conditions in lab scale you need to have a versatile apparatus and you will need to use the actual components to be as close to reality as possible.  

HOW ?  : A Basalt-S2 was used to simulate the motion of the wiper blades (reciprocating nonlinear sliding motion). A sprinkler can be added to the apparatus to spray different volumes of water at different intervals. The aim is to simulate the “actual” conditions. Glass was used as a countermaterial. In this application we first present the effect of water in the friction of commercial wipers and secondly we compare different wipers for the same conditions (speed, load, water volume) to have a ranking. With the same setup the effect of particles (e.g. sand, dust etc.) can also be studied by either changing the composition of the water that is sprayed onto the glass, or by applying a layer soil/dust directly on the glass.

 

b2ap3_large_S2-machine Applications  

RESULT :

- The Basalt-S2 can be used to measure the friction of wiper blades in contact with glass.

- The frictional behavior of a wiper strongly depends on the speed, water volume and particle concentration.

- A ranking between different commercial wiper blades at various conditions is possible.

 

b2ap3_large_Wiper-blade-A_COF_Dry-sliding_with-label Applications b2ap3_large_Wiper-blade-A_COF_Wet-sliding_with-label Applications
b2ap3_large_Wiper-blade-A_COF_Wet-sliding_with-label Applications b2ap3_large_Wiper-blade-B_COF_Wet-sliding_with-label Applications

 

 

 

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