The Dependence of the Friction Coefficient on the Size and Course of Sliding Speed

2014 ◽  
Vol 693 ◽  
pp. 305-310 ◽  
Author(s):  
Eva Labašová
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
Testing Machine ◽  
Current Component ◽  
Sliding Speed ◽  
Rectangular Shape ◽  
Coefficient Increase ◽  
The Coefficient Of Friction ◽  
Ring Method ◽  
Run Up

The coefficient of friction for the bronze material (CuZn25Al6) with insert graphite beds and other bronze material (CuSn12) are investigated in this paper. Friction coefficient was investigated experimentally by the testing machine Tribotestor`89 which uses the principle of the ring on ring method. The external fixed bushing was exposed to the normal load of the same size in all tests. Process of load was increased from level 50 N to 600 N during run up 300 s, after the run up the appropriate level of load was held. The internal bushing performed a rotational movement with constant sliding speed. The value of sliding speed was changed individually for every sample (v = 0.2 (0.3, 0.4) m.s-1). The forth test had a rectangular shape of sliding speed with direct current component 0.3 m.s-1 and the amplitude 0.1 m.s-1 period 300 s, the whole test took 2100 s. The obtained results reveal that friction coefficient increase with the increase of sliding speed.

The Size of the Friction Coefficient Depending on the Size and Course of Normal Load

2014 ◽  
Vol 474 ◽  
pp. 303-308 ◽  
Author(s):  
Eva Labašová
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Normal Load ◽  
Testing Machine ◽  
Constant Load ◽  
Current Component ◽  
Rectangular Shape ◽  
The Coefficient Of Friction ◽  
Ring Method ◽  
Run Up

The coefficient of friction for the bronze material (CuZn25Al6) with inset graphite beds is investigated in the present paper. Friction coefficient was investigated experimentally by the testing machine Tribotestor`89 which uses the principle of the ring on ring method. Tribotestor`89 machine may be classed to the rotary tribometers. The tested sliding pairs were of the same material. The internal bushing performed a rotational movement with constant sliding speed (v = 0.8 m s-1). The external fixed bushing was exposed to the normal load, which was of different sizes and different variations. Process of load was increased from level 50 N to 200 N (400 N, 600 N) during run up 600 s, after the run up the appropriate level of load was held.The forth test had a rectangular shape of loading with direct current component 400 N and the amplitude 200 N period 600 s, the whole test took 1800 s. The obtained results reveal that friction coefficient decreases with the increase of normal load. Further, that the coefficient of friction was found smaller at constant load, as compared to rectangular shape of loading.

scholarly journals Experimental Study on the Transition between Static and Kinetic Frictions of Steel/Shale Pairs

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Qin Lian ◽  
Chunxu Yang ◽  
Jifei Cao
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
Critical Distance ◽  
Dynamic Friction ◽  
Stick Slip ◽  
Dynamic Friction Coefficient ◽  
The Coefficient Of Friction ◽  
The Difference ◽  
Stick Slip Motion ◽  
Insight Into

The transition between static and kinetic frictions of steel/shale pairs has been studied. It was found that the coefficient of friction decreased exponentially from static to dynamic friction coefficient with increasing sliding displacement. The difference between static and dynamic friction coefficients and the critical distance Dc under the dry friction condition is much larger than that under the lubricated condition. The transition from static to dynamic friction coefficient is greatly affected by the normal load, quiescent time, and sliding velocity, especially the lubricating condition. Maintaining continuous lubrication of the contact area by the lubricant is crucial to reduce or eliminate the stick-slip motion. The results provide an insight into the transition from static to dynamic friction of steel/shale pairs.

scholarly journals Effect of Self-Generated Transfer Layer on the Tribological Properties of PTFE Composites Sliding against Steel

Coatings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 399 ◽  
Author(s):  
Ting Xie ◽  
Shihao Feng ◽  
Yongheng Qi ◽  
Ailong Cui
Keyword(s):  
Friction Coefficient ◽  
Layer Thickness ◽  
Tribological Properties ◽  
Normal Load ◽  
Wear Test ◽  
Wear Volume ◽  
Functional Requirements ◽  
Transfer Layer ◽  
Sliding Speed ◽  
Ptfe Composites

Coatings are normally employed to meet some functional requirements. There is a kind of self-generated coating during use, such as the transfer layer during sliding, which may greatly affect the tribological behavior. Although the transfer layer has aroused much attention recently, the formation of the transfer layer closely depends on the service conditions, which need to be further studied. In this paper, the effects of sliding speed, normal load, and duration of wear test on the transfer layer thickness during friction of Ni/PTFE (Polytetrafluoroethylene) composites were experimentally investigated. The formation mechanism of transfer layer and the relationships between tribological properties and transfer layer thickness were analyzed in detail. It was found that the transfer layer thickness increased with increases of sliding speed and normal load; and after a period of wear test, the transfer layer thickness remained stable. The transfer layer thickness correlates linearly with the friction coefficient and wear volume of the PTFE composites. With the increase of the transfer layer thickness, the friction coefficient decreased, while the wear volume increased, which means that a uniform, thin, and stable transfer layer is beneficial for the reduction of friction and wear of the polymeric composites.

Measurement of Tribological Parameters

2014 ◽  
Vol 875-877 ◽  
pp. 496-499 ◽  
Author(s):  
Eva Labašová ◽  
Rastislav Ďuriš
Keyword(s):  
Coefficient Of Friction ◽  
Test Equipment ◽  
Tribological Characteristics ◽  
Sliding Speed ◽  
Sliding Joint ◽  
The Coefficient Of Friction ◽  
Run Up ◽  
Tribological Parameters

The contribution deals with measurement of the coefficient of friction in the sliding joint. Rotanional sliding pair, which was tested, is described in this paper. Their tribological characteristics were measured by test equipment Tribotestor`89. The value of the coefficient of friction for the bushings from brass, aluminium and polyamide for chosen load (the sliding speed, loading, duration) are analysed in the paper. The largest decrease in the size of the coefficient of friction was recorded for bushings from aluminium, its value have decreased by 87.5% during the run up. Decrease of the coefficient of friction was recorded about 82% for bushings from brass and about 72% for bushings from polyamide. Run up lasted 10 minutes in all tests.

The Effect of Sliding Speed on Friction and Wear of RBD Palm Olein

2013 ◽  
Vol 315 ◽  
pp. 951-955 ◽  
Author(s):  
Samion Syahrullail ◽  
Jazair Yahya Wira ◽  
W.B. Wan Nik ◽  
Chiong Ing Tiong
Keyword(s):  
Friction Coefficient ◽  
Friction And Wear ◽  
Palm Olein ◽  
Normal Load ◽  
Mineral Oil ◽  
Low Friction ◽  
Sliding Speed ◽  
Rbd Palm Olein

In this paper, the effect of sliding speed on the anti-friction of RBD palm olein was investigated using four-ball tribotester. The speeds were varied from 800 to 1400 rpm. The normal load was set to 40 kg and the test oil was heated up to 75 °C before the experiments. The result showed that palm olein has low friction coefficient compared to additive-free paraffinic mineral oil.

Transition of Wear Mechanisms of Plasma Source Nitrided AISI 316 Austenitic Stainless Steel Against Ceramic Counterface

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
G. Y. Li ◽  
Z. Y. Wang ◽  
M. K. Lei
Keyword(s):  
Electron Microscopy ◽  
Stainless Steel ◽  
Friction Coefficient ◽  
Wear Rate ◽  
Normal Load ◽  
Plasma Source ◽  
Specific Wear Rate ◽  
Phase Layer ◽  
Sliding Speed ◽  
Aisi 316

A single high-nitrogen face-centered-cubic (f.c.c.) phase (γN) layer formed on the plasma source nitrided AISI 316 austenitic stainless steel at a nitriding temperature of 450 °C for a nitriding time of 6 h. An approximately 17 μm-thick γN layer has a peak nitrogen concentration of about 20 at. %. Tribological properties of the γN phase layer on a ball-on-disk tribometer against an Si3N4 ceramic counterface under a normal load of 2 and 6 N with a sliding speed of 0.15 to 0.29 m/s were investigated by friction coefficient and specific wear rate measurement. Worn surface morphology and wear debris were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The microhardness of the γN phase layer on the nitrided stainless steel was measured as about 15.1 GPa. The change in the friction coefficient of the γN phase layer on the stainless steel was dependent on the applied normal load, which was associated with that in the specific wear rate. Under a lower normal load of 2 N, the lower specific wear rate of the γN phase layer with a sliding speed of 0.15 m/s was obtained as 2.8 × 10−6 mm3/N m with a friction coefficient of 0.60. Under a higher normal load of 6 N, the lower specific wear rate with a sliding speed of 0.29 m/s was 7.9 × 10−6 mm3/N m with a friction coefficient of 0.80. When the applied load increased from 2 to 6 N, a transition of the wear mechanisms from oxidative to abrasive wear was found, which was derived from the oxidation reaction and the h.c.p. martensite phase transformation of the γN phase during the wear tests, respectively.

The Mechanical Properties and Friction and Wear Behavior of C/C-SIC

2010 ◽  
Author(s):  
Gao Wen ◽  
Chongsheng Long ◽  
Tang Rui ◽  
Jiping Wang
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Friction And Wear ◽  
Wear Behavior ◽  
Normal Load ◽  
Carbon Matrix ◽  
Specific Wear Rate ◽  
Sliding Speed ◽  
Wear Rates ◽  
Sic Composites

Carbon fiber reinforced carbon-silicon carbide composites (C/C-SiC) were prepared by chemical volume infiltration (CVI) method and reaction melt infiltration (RMI) technique of silicon liquid to carbon reinforce carbon matrix composites. The friction and wear behaviors of C/C-SiC composites at various loads and sliding speeds were investigated by MRH-3 block-on-ring tribometer at room temperature under water lubricating conditions. Furthermore, the morphologies, phase of the worn surface and the debris were observed, examined and analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDAX) respectively. Experimental results showed that the C/C-SiC composites had a better wear resistence, and the friction coefficient under water lubricated conditions is about 0.02–0.06. The influence of sliding speed on the friction coefficients and the specific wear rate of C/C-SiC is more obvious than that of normal load when the load is less than 200N (inclueded200N). The friction coefficient and the specific wear rate of C/C-SiC decreased as the sliding velocity increased. At the sliding speed higher than 2m/s, the friction coefficient is less than 0.02. The specific wear rates is at a low level about (2×10−7mm3/Nm–5×10−8mm3/Nm).

scholarly journals Determination of the Coefficient of Friction Under Cold Tube Drawing Using FEM Simulation and Drawing Force Measurement

2018 ◽  
Vol 26 (42) ◽  
pp. 29-34 ◽  
Author(s):  
Martin Necpal ◽  
Maroš Martinkovič ◽  
Štefan Václav
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Tensile Testing ◽  
Force Measurement ◽  
Testing Machine ◽  
Fem Simulation ◽  
Tensile Testing Machine ◽  
Additional Equipment ◽  
The Coefficient Of Friction ◽  
Cold Draw

Abstract The purpose of this article is to describe the methodology to define coefficient of friction between a tool and a forming material during tube cold draw technology process. In this regard, an experimental drawing process was done by using the tensile testing machine. The tensile testing machine was modified by additional equipment that allows drawing the tube. During the drawing, the force was recorded. Subsequently, the finite element simulation of cold draw forming was used to generate load-stroke curves with different friction coefficient. The friction coefficient was estimated by comparing the load stroke and the force recorded curves.

Paper 19: Unlubricated Sliding at High Speeds between Copper and Steel Surfaces

1966 ◽  
Vol 181 (15) ◽  
pp. 25-30 ◽  
Author(s):  
M. J. Kadhim ◽  
S. W. E. Earles
Keyword(s):  
Oxide Layer ◽  
Coefficient Of Friction ◽  
Normal Load ◽  
Sliding Speed ◽  
Wear Rates ◽  
High Speeds ◽  
Before And After ◽  
The Coefficient Of Friction ◽  
Steel Disc ◽  
Steel Surfaces

Experiments are described in which stationary copper specimens are rubbed in a normal atmosphere against a rotating S62 steel disc under normal loads up to 4·5 lbf. The coefficient of friction is measured at sliding speeds of 93, 220, 328, and 490 ft/s using ⅛-in diameter specimens. Except at the lowest speed a gradual buildup of a continuous copper oxide layer on the disc track is observed with increasing normal load together with a corresponding decrease in the coefficient of friction. Having established an oxide layer on the track the coefficient of friction observed is low for all normal loads. The coefficient of friction is shown to decrease with normal load N and sliding speed U, to be a function of N1/2 U, and to depend on the state of the disc surface. Wear of -in diameter specimens is measured by weighing before and after a test. The wear rate is shown to decrease with sliding speed and increase with load, and for speeds of 220 and 328 ft/s to be a function of N/U. The wear rates measured at 93 ft/s are the same function of N/U for low values of N/U.

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