Application Examples

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How to measure the friction and adhesion of skin creams

WHY ?  : Skin creams are commonly used to improve skin health and create a smooth, soft, and moist perception. This is achieved by altering the surface roughness, friction, and adhesion of skin surface. Despite the fact that there are many commercial creams available, there is no consistent approach to determine their frictional and adhesive properties.

HOW ?  : Two different test procedures are developed to evaluate the friction and adhesion of commercial skin creams. To investigate the frictional behavior, a reciprocating sliding was performed by applying a film of cream on an artificial skin. As a counter material, silicone was used to simulate the actual tribosystem. Different sliding speeds, applied loads and sliding distances can be used to evaluate and compare different contact conditions. In addition, the adhesion of the skin creams was measured based on approach-retraction curves. In this procedure a silicone counter body gradually approaches the artificial skin with the cream, until a pre-set contact load is reached. Then, the silicone moves away from the greased substrate under well controlled conditions, until complete physical separation is achieved.  During this approach-retraction cycle, the force on the load sensor is measured as a function of time and distance moved. 

 

b2ap3_thumbnail_PICTURE consumer products - Application examples | FACTLABS.ORG

 

RESULT  :

- The frictional behavior of various creams can be investigated in an accurate and efficient way, under realistic conditions.

- The same apparatus and setup can also be used to measure the adhesion and separation energy of creams on artificial skin. 

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How can we measure the friction and wear of wires in sliding contacts?

WHY ?  : In our everyday life we come across and use applications were wire are operated in a sliding contact. Some indicative examples are elevators, car doors, canopies etc. In the majority of these applications friction there are limitation in terms of friction (e.g. the wire in a canopy should slide smoothly), whereas after a period of time localized wear of the wire can occur in the contact due to combination of the motion and the loading (e.g. wire in an elevator).    

HOW ?  : A Basalt-N2 was used to perform reciprocating sliding tests between wires and metallic countermaterials. Holders having different diameters were designed and manufactured to clamp the different wires. To maintain the same contacting surface during each test and between different tests, a self-aligning holder was manufactured to correctly align and hold the cylinder in contact with the wire. The load and contact pressures were calculated by Hertzwin software to be in accordance with the in-field conditions. The evolution of the coefficient of friction was continuously monitored, whereas the wear damage on both the wire and the countermaterial (tool steel cylinder) was measured by 3D confocal microscopy. Multiple tests were performed per wire to evaluate the repeatability of tribological data and to perform a statistical analysis.

 

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RESULT :

- A new method to measure the friction and wear on wires in sliding contacts was developed for the Basalt-N2.

- Very high repeatability in friction data.

- Differences in the friction and wear of various commercial wires could be discerned.

- Statistical analysis of tribological data increases the confidence levels and helps to point-out outliers.

 

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 b2ap3_thumbnail_Wear-evaluation-of-wires Applications

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