Effect of Velocity and Load on the Development of Kinetic Friction at a Lubricated Steel on Polymer Interface

Author(s):  
Matthew M. Bunten ◽  
Shannon J. Timpe

The effect of normal load and sliding velocity on the development of friction at a lubricated steel pin on polymer disk interface was investigated. Polyoxymethylene homopolymer disks were lubricated with a lithium soap thickened synthetic hydrocarbon grease and tested against a 6 mm diameter stainless steel pin. The normal load was varied from 3 to 80 N, and the sliding velocity was varied from 0.0004 to 0.2 m/s. The engineering friction coefficient displayed a power law dependence on the external applied load, indicating a significant adhesive effect in the presence of the lubricant. The true friction coefficient was 0.04, and the average adhesion force was calculated to be 29 N. With the soft disk and hard pin configuration, velocity and time effects were found to be negligible in the presence of the dominant dependence on the normal load. However, a velocity effect emerged with steel disks and polymer pins, likely due to a temperature rise at the polymer surface.

Author(s):  
Dewan Muhammad Nuruzzaman ◽  
Mohammad Asaduzzaman Chowdhury

This paper examines the relation between friction/wear and different types of steel materials under different normal loads and sliding velocities and to explore the possibility of adding controlled normal load and sliding velocity to a mechanical process. In order to do so, a pin on disc apparatus is designed and fabricated. Experiments are carried out when different types of disc materials such as stainless steel 304 (SS 304), stainless steel 316 (SS 316) and mild steel slide against stainless steel 304 (SS 304) pin. Variations of friction coefficient with the duration of rubbing at different normal loads and sliding velocities are investigated. Results show that friction coefficient varies with duration of rubbing, normal load and sliding velocity. In general, friction coefficient increases for a certain duration of rubbing and after that it remains constant for the rest of the experimental time. The obtained results reveal that friction coefficient decreases with the increase in normal load for all the tested materials. It is also found that friction coefficient increases with the increase in sliding velocity for all the materials investigated. Moreover, wear rate increases with the increase in normal load and sliding velocity. At identical operating condition, the magnitudes of friction coefficient and wear rate are different for different materials depending on sliding velocity and normal load.


1995 ◽  
Vol 117 (4) ◽  
pp. 569-574 ◽  
Author(s):  
Yasuhisa Ando ◽  
Yuichi Ishikawa ◽  
Tokio Kitahara

The friction coefficient and adhesion force between steel balls and flat test pieces were measured during friction under low normal load in order to examine the tribological characteristics. First, the friction coefficients were measured under a constant normal load of 0.8 to 2350 μN, and the adhesion forces were measured before and after each friction. The result showed that the friction coefficient was highest at low normal loads, while the friction force divided by the sum of the normal load and the mean adhesion force was almost constant over the whole range of loads. Second, when the normal load was reduced gradually during friction, friction still acted when the normal load became negative and a pulling off force was applied to the surface. Thus an adhesion force acts during friction and this adhesion force affects the friction force in the same way as the normal load.


2018 ◽  
Vol 70 (2) ◽  
pp. 273-281 ◽  
Author(s):  
Xiaoshuang Xiong ◽  
Lin Hua ◽  
Xiaojin Wan ◽  
Can Yang ◽  
Chongyang Xie ◽  
...  

Purpose The purposes of this paper include studying the friction coefficient of polyoxymethylene (POM) under a broad range of normal load and sliding velocity; developing a mathematical model of friction coefficient of POM under a broad range of normal loads and sliding velocities; and applying the model to dynamic finite element (FE) analysis of mechanical devices containing POM components. Design/methodology/approach Through pin-on-disc experiment, the friction coefficient of POM in different normal loads and sliding velocities is investigated; the average contact pressure is between 5 and 15 Mpa and the sliding velocity is from 0.05 to 0.9 m/s. A friction algorithm is developed and embedded in the FE model to simulate the friction of POM in different normal loads and sliding velocities. Findings The friction coefficient of POM against steel declines with the increase of normal loads when the contact pressure is between 5 and 15 Mpa. The friction coefficient of POM against steel increases markedly when the sliding velocity is between 0.05 and 0.15 m/s, it decreases sharply between 0.15-0.45 m/s and then it stabilizes at high sliding velocity between 0.45 and 0.9 m/s. The friction coefficient of POM in different working operations has a significant effect on contact stress and shear stress. The simulation data and experiment data of POM friction force fit very well; therefore, it can be concluded that the friction algorithm and FE model are accurate. Originality/value The friction coefficient of POM under a broad range of normal loads and sliding velocities is investigated. The friction coefficient model of POM is established as a function of normal loads and sliding velocities in the dry sliding condition. A friction algorithm is developed and embedded in the FE model of the friction of POM. The mathematical model of the friction coefficient accurately agrees with the experiment data, and simulation data and experiment data of the POM friction force fit very well.


2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
M. Sudheer ◽  
Ravikantha Prabhu ◽  
K. Raju ◽  
Thirumaleshwara Bhat

The dry sliding friction and wear behavior of epoxy hybrid composites reinforced with glass fibers and a varying amount of potassium titanate whiskers (PTWs) fabricated by vacuum hand layup method were studied. The influence of normal load, sliding velocity, and whisker content on both friction coefficient and specific wear rate was investigated on a pin-on-disc machine. The tests were conducted at ambient conditions based on the 3 × 3 (3 factors at 3 levels) full factorial design. Analysis of variance (ANOVA) was performed to obtain the contribution of control parameters on friction coefficient and wear rate. The density and hardness of the composites were found to be enhanced with the PTW loading. The friction coefficient and wear resistance of the hybrid composites were found to be improved with the whisker content and were also greatly influenced by normal load and sliding velocity. A correlation between dry sliding wear behaviors of composites with wear parameters was obtained by multiple regressions. The worn out surface of selected samples was observed under scanning electron microscope (SEM) to identify wear mechanisms. This study revealed that the addition of the ceramic microfillers such as PTW improves the wear performance of the epoxy/glass polymer composites significantly.


2007 ◽  
Vol 336-338 ◽  
pp. 1740-1742
Author(s):  
Fang Wu ◽  
Sheng Ming Xu ◽  
Song Zhe Chen ◽  
Lin Yan Li ◽  
Gang Xu ◽  
...  

Tribological behavior of B4C-SiC self-mated pairs was studied, and pre-oxidation treatment was adopted to improve the tribological properties of B4C-SiC. At the same SiC content, self-friction coefficient of B4C-SiC decreases with the increase of sliding distance, normal load, and sliding velocity; while the increasing of SiC content leads to increase of both self-friction coefficient and ware rate, which was determined to be within the range of 0.8×10-6~5.8×10-6 mm3·N-1·m-1. Pre-oxidation treatment of the B4C-SiC resulted in the formation of B2O3/H3BO3 lubricant layers, which effectively reduced the self-friction coefficient.


2014 ◽  
Vol 903 ◽  
pp. 90-95
Author(s):  
Mohammad Lutfar Rahaman ◽  
Mohammad Asaduzzaman Chowdhury ◽  
Dewan Muhammad Nuruzzaman

In this research, friction coefficients of engineering polymers such as nylon and polytetrafluoroethylene (PTFE) are investigated under normal load and sliding velocity. Experiments are conducted when nylon and PTFE slide against different counterface pin materials such as mild steel and stainless steel 202 (SS 202). Experiments are carried out at different normal loads 2, 4 and 6 N, and sliding velocities 0.2, 0.4 and 0.6 m/s. Results show that in general, friction coefficient of nylon decreases with the increase in normal load and sliding velocity. On the other hand, during friction process, PTFE shows different trend i.e. friction coefficient of PTFE increases with the increase in normal load and sliding velocity. Moreover, it is observed that at identical operating conditions, the values of friction coefficient of nylon and PTFE are different depending on normal load, sliding velocity and counterface material.


2012 ◽  
Vol 576 ◽  
pp. 590-593
Author(s):  
Dewan Muhammad Nuruzzaman ◽  
Mohammad Asaduzzaman Chowdhury

An endeavor has been made to study and compare the friction coefficient of different polymer and composite materials. Experiments were carried out when stainless steel 304 (SS 304) pin slides on different types of composite and polymer materials such as cloth reinforced ebonite (commercially known as gear fiber), glass fiber reinforced plastic (glass fiber), nylon and polytetrafluoroethylene (PTFE). Experiments were conducted at normal load 5, 7.5, 10 N, sliding velocity 0.5, 0.75, 1 m/s and relative humidity 70%. Variations of friction coefficient with the duration of rubbing at different normal loads and sliding velocities were investigated. Results show that friction coefficient varies with duration of rubbing, normal load and sliding velocity. In general, friction coefficient increases with the increase in normal load and sliding velocity for all the tested materials except nylon. At identical operating conditions, the magnitudes of friction coefficient are different for different polymer and composite materials.


2021 ◽  
Vol 29 (3) ◽  
Author(s):  
Emad Kamil Hussein ◽  
Kussay Ahmed Subhi ◽  
Tayser Sumer Gaaz

The present paper investigates experimentally effect of applied load and different velocity on the coefficient of friction between two interacting surfaces (human skin and Ultra-high-molecular-weight polyethylene (UHMW- polyethylene) at static and dynamic friction. It is possible to conclude specific point based on the above practical part and frictional analysis of this investigation as the most important mechanical phenomenon was creep has been observed a stick time interval where the static friction force is significantly increased during this stroke. The analytical model for stick-slip of skin and UHMWPE is proposed. The difference between static and kinetic friction defines the amplitude of stick-slip phenomena. The contact pressure, the sliding velocity, and rigidity of system determine the stability conditions of the movement between skin and UHMWPE. Experiments were carried out by developing a device (friction measurement). Variations of friction coefficient during the time at different normal load 4.6 and 9.2 N and low sliding velocity 4, 5, 6 and 7 mm/min were experimentally investigated. The results showed that the friction coefficient varied with the normal load and low sliding velocity. At static friction, the coefficient of friction decreased when the time increases, whereas, at dynamic friction, the coefficient of friction decreased when the time increased at normal load 4.6 and 9.2 N.


2014 ◽  
Vol 903 ◽  
pp. 33-38
Author(s):  
Mohammad Asaduzzaman Chowdhury ◽  
Dewan Muhammad Nuruzzaman ◽  
Mohammad Lutfar Rahaman

In this study, friction coefficients of different steel materials are investigated and compared. Experiments are carried out when different types of steel discs such as stainless steel 201 (SS 201), stainless steel 301 (SS 301) and mild steel slide against mild steel pin. Experiments are conducted at normal load 5, 7.5 and 10 N, sliding velocity 0.5, 0.75 and 1 m/s and relative humidity 70%. The effects of duration of rubbing on the friction coefficient of different steel materials are investigated. Results show that during friction process, test disc takes less time to stabilize with the increased normal load or sliding velocity. It is found that friction coefficient decreases with the increase in normal load while it increases with the increase in sliding velocity for all the tested materials. As a comparison, it is found that at identical operating conditions, friction coefficients are different for different steel materials depending on normal load or sliding velocity.


Author(s):  
E. Y. A. Wornyoh ◽  
C. F. Higgs ◽  
R. Pudjoprawoto

Experiments were conducted to examine the effects of friction coefficient on sliding velocity at a slider pad/disk interface lubricated by MoS2 powder film. The powder film was obtained by shearing compacted pellets of MoS2 against a tungsten carbide (WC) disk and was responsible for supporting the slider pad load. The results from the experiments showed that an adverse interfacial friction coefficient leads to a decrement in the sliding velocity. Contrarily, an increased sliding velocity accompanies a favorable (i.e., smaller) friction coefficient at the WC slider pad/disk interface lubricated by the MoS2 powder lubricant film.


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