scholarly journals An Experimental Study of Micro-Dimpled Texture in Friction Control under Dry and Lubricated Conditions

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 70
Author(s):  
Yuan Wei ◽  
Jesus Resendiz ◽  
Robert Tomkowski ◽  
Xu Liu
Keyword(s):  
Sustainable Development Goals ◽  
Surface Texturing ◽  
Friction Reduction ◽  
Experimental Conditions ◽  
Dominant Mechanism ◽  
Friction Control ◽  
The Coefficient Of Friction ◽  
Development Goals ◽  
Lubrication Conditions ◽  
Density Results

Friction control is a vital technology for reaching sustainable development goals, and surface texturing is one of the most effective and efficient techniques for friction reduction. This study investigated the performance of a micro-dimpled texture under varying texture densities and experimental conditions. Reciprocating sliding tests were performed to evaluate the effects of the micro-dimpled texture on friction reduction under different normal loads and lubrication conditions. The results suggested that a micro-dimpled texture could reduce the coefficient of friction (CoF) under dry and lubricated conditions, and high dimple density results in a lower CoF. The dominant mechanism of the micro-dimpled texture’s effect on friction reduction was discussed, and surface observation and simulation suggested that a micro-dimpled texture could reduce the contact area at the friction interface, thereby reducing CoF.

scholarly journals A Study of Micro-Dimpled Groove Texture in Friction Reduction

2021 ◽  
Author(s):  
Yuan Wei ◽  
Xu Liu ◽  
Simon S. Park ◽  
Robert Tomkowski ◽  
Andreas Archenti
Keyword(s):  
Surface Texturing ◽  
Sample Surface ◽  
Green Technology ◽  
Friction Reduction ◽  
Laser Marking ◽  
Friction Control ◽  
The Coefficient Of Friction ◽  
Dimple Surface ◽  
Development Goals ◽  
Groove Texture

Abstract Friction control is a vital green technology for reaching sustainable development goals, and surface texturing is effective and efficient at reducing friction. In this study, a novel preparation scheme involving dimpled groove texture is proposed. A pulsed laser marking system is used to make the dimpled grooves. Due to the unique design and process to make the proposed texture, texturing time can be greatly minimized compared to the conventional micro-groove texture technology. A computational fluid dynamics (CFD) model that considers the dimple surface angle is employed to aid the design of the texture and to predict the performance of the texture under certain conditions. Reciprocating sliding tests are preformed to evaluate the effects of the texture on friction reduction. Textures with different densities are used in the experiments. The results suggest that the dimpled groove reduces the coefficient of friction by 6% with less density distribution on the sample surface; nevertheless, denser densities may reverse the result. The simulation results suggest that the texture may perform better under pressure of the lubricant film in hydrodynamic conditions.

scholarly journals Possibilities of Dry and Lubricated Friction Modification Enabled by Different Ultrashort Laser-Based Surface Structuring Methods

Lubricants ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 43 ◽  
Author(s):  
Stefan Rung ◽  
Kevin Bokan ◽  
Frederick Kleinwort ◽  
Simon Schwarz ◽  
Peter Simon ◽  
...  
Keyword(s):  
Laser Beam ◽  
Surface Engineering ◽  
Surface Texturing ◽  
Friction Reduction ◽  
Surface Structures ◽  
Laser Surface Texturing ◽  
Periodic Surface ◽  
The Coefficient Of Friction ◽  
Disc Configuration ◽  
Micro Structures

In this contribution we report on the possibilities of dry and lubricated friction modification introduced by different laser surface texturing methods. We compare the potential of Laser-Induced Periodic Surface Structures and Laser Beam Interference Ablation on 100Cr6 steel in a linear reciprocating ball-on-disc configuration using 100Cr6 steel and tungsten carbide balls with load forces between 50 mN and 1000 mN. For dry friction, we find a possibility to reduce the coefficient of friction and we observe a pronounced direction dependency for surfaces fabricated by Laser Beam Interference Ablation. Furthermore, Laser-Induced Periodic Surface Structures result in a load-dependent friction reduction for lubricated linear reciprocating movements. This work helps to identify the modification behaviour of laser generated micro structures with feature sizes of approximately 1 µm and reveals new possibilities for surface engineering.

Manufacturing and Tribological Investigation of Hot Micro-Coined Lubrication Pockets

2014 ◽  
Vol 611-612 ◽  
pp. 417-424 ◽  
Author(s):  
Adam Szurdak ◽  
Andreas Rosenkranz ◽  
Carsten Gachot ◽  
Gerhard Hirt ◽  
Frank Mücklich
Keyword(s):  
Friction And Wear ◽  
Surface Texturing ◽  
Wear Volume ◽  
Forming Process ◽  
Surface Textures ◽  
The Coefficient Of Friction ◽  
Steel Aisi ◽  
Machine Elements ◽  
Tool Damage ◽  
Lubrication Conditions

Friction and wear of lubricated machine elements can be reduced by the introduction of lubrication pockets produced by surface texturing. Different manufacturing methods can be taken into consideration whereas a forming process offers the possibility for mass production. Hot micro coining is a forming process, which allows manufacturing of surface textures with different shapes and dimensions into a flat and deformable material, e.g. seals made of steel. In this work hemispherical and ellipsoid pockets with a maximum depth of 100 µm have been embossed into stainless steel (AISI 304). To ensure that the used process parameters will not lead to tool damage, Finite Element simulations were performed and experimentally verified. First tribological experiments were conducted on a ball-on-disk tribometer in order to study the tribological properties of hemispherical structures with pockets depths of 50 and 100 µm. Different sliding velocities were applied to study the coefficient of friction and wear volume for different lubrication conditions. A comparison between coined and not‑coined specimens demonstrates that the micro coined surface textures lead to a significant reduction in the wear volume at boundary and mixed lubrication conditions.

scholarly journals An Experimental Study of the Frictional Properties of Steel Sheets Using the Drawbead Simulator Test

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4037 ◽  
Author(s):  
Trzepiecinski ◽  
Kubit ◽  
Slota ◽  
Fejkiel
Keyword(s):  
Coefficient Of Friction ◽  
Extreme Values ◽  
Rolling Direction ◽  
Frictional Resistance ◽  
Friction Reduction ◽  
Experimental Investigations ◽  
Sheet Rolling ◽  
The Coefficient Of Friction ◽  
The Difference ◽  
Lubrication Conditions

This article presents the results of an experimental investigation of the frictional resistance arising in a drawbead during sheet metal forming. The frictional characterization of DC04 deep drawing quality steels commonly used in the automotive industry is carried out using a friction simulator. The effects of some parameters of the friction process on the value of the coefficient of friction have been considered in the experimental investigations. The friction tests have been conducted on different strip specimens, lubrication conditions, heights of drawbead and specimen orientations in relation to the sheet rolling direction. The results of drawbead simulator tests demonstrate the relationship that the value of the coefficient of friction of the test sheets without lubrication is higher than in the case of lubricated sheets. The lubricant reduces the coefficient of friction, but the effectiveness of its reduction depends on the drawbead height and lubrication conditions. Moreover, the effectiveness of the reduction of the coefficient of friction by the lubricant depends on the specimen orientation according to the sheet rolling direction. In the drawbead test, the specimens oriented along the rolling direction demonstrate a higher value of coefficient of friction when compared to the samples cut transverse to the rolling direction. The smaller the width of the specimen, the lower the coefficient of friction observed. The difference in the coefficient of friction for the extreme values of the widths of the specimens was about 0.03–0.05. The use of machine oil reduced the coefficient of friction by 0.02–0.03 over the whole range of drawbead heights. Heavy duty lubricant even reduced the frictional resistances by over 50% compared to dry friction conditions. The effectiveness of friction reduction by machine oil does not exceed 30%.

Restructuring Educational Systems and Promoting Social Justice for Young People Involved in Drug Trafficking in Brazil

2019 ◽  
Vol 227 (2) ◽  
pp. 139-143 ◽  
Author(s):  
Alex Sandro Gomes Pessoa ◽  
Linda Liebenberg ◽  
Dorothy Bottrell ◽  
Silvia Helena Koller
Keyword(s):  
Sustainable Development ◽  
Social Justice ◽  
Young People ◽  
Latin American ◽  
Drug Trafficking ◽  
Sustainable Development Goals ◽  
Educational Systems ◽  
Economic Changes ◽  
2030 Agenda ◽  
Development Goals

Abstract. Economic changes in the context of globalization have left adolescents from Latin American contexts with few opportunities to make satisfactory transitions into adulthood. Recent studies indicate that there is a protracted period between the end of schooling and entering into formal working activities. While in this “limbo,” illicit activities, such as drug trafficking may emerge as an alternative for young people to ensure their social participation. This article aims to deepen the understanding of Brazilian youth’s involvement in drug trafficking and its intersection with their schooling, work, and aspirations, connecting with Sustainable Development Goals (SDGs) 4 and 16 as proposed in the 2030 Agenda for Sustainable Development adopted by the United Nations in 2015 .

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