Frictional Properties of a Surface Covered With a Soft Metal Film—Part 1: Experiments on Friction Between a Single Protuberance and a Surface

1981 ◽  
Vol 103 (2) ◽  
pp. 236-242 ◽  
Author(s):  
S. Kato ◽  
K. Yamaguchi ◽  
E. Marui ◽  
K. Tachi
Keyword(s):  
Coefficient Of Friction ◽  
Deformation Mechanism ◽  
Metal Film ◽  
Surface Film ◽  
Thin Metal Film ◽  
Film Properties ◽  
Empirical Expression ◽  
Frictional Properties ◽  
The Coefficient Of Friction ◽  
Soft Metal

Frictional properties in the contact between a hard protuberance and a metal surface covered by a soft thin metal film are examined experimentally. The protuberance used in the experiment is a hard steel ball which simulates asperities on many engineering surfaces. The load dependency of the coefficient of friction and the effects of thickness and hardness of the film on the friction are clarified. The simple empirical expression of friction, which represents the effect of the film properties, is presented, considering the deformation mechanism of the surface film.

Frictional Properties of a Surface Covered With a Soft Metal Film—Part 2: Analysis of Friction Between a Single Protuberance and a Surface

1982 ◽  
Vol 104 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Shinobu Kato ◽  
Katsumi Yamaguchi ◽  
Etsuo Marui ◽  
Kiyoo Tachi
Keyword(s):  
Pressure Distribution ◽  
Coefficient Of Friction ◽  
Metal Film ◽  
Surface Film ◽  
Analytical Investigation ◽  
Friction Characteristic ◽  
Frictional Properties ◽  
The Coefficient Of Friction ◽  
Soft Metal ◽  
Side Flow

Analytical investigation of the evaluation of the coefficient of friction is made to clarify the mechanism of the load dependency of friction, which was obtained in Part 1 of this research, and also to ascertain the effects of the surface film on the friction characteristic. The plastic flow of the soft metal film between a protuberance and the subsurface is presumed, and the pressure distribution originating from the side flow is calculated on the basis of the plasticity theory. The effects of the coefficient of friction of the load, the thickness and hardness of the film, and the radius of the protuberance, are examined. As a result, it is clarified that the load dependency of friction arises from the extremely high pressure distribution generated in the film.

Frictional Properties of a Surface Covered With Soft Metal Film (Interference Effect of Soft Metal Film Deformation Between Two Protuberances)

1985 ◽  
Vol 107 (4) ◽  
pp. 444-451 ◽  
Author(s):  
Shinobu Kato ◽  
Etsuo Marui ◽  
Kiyoo Tachi
Keyword(s):  
Plastic Flow ◽  
Interference Effect ◽  
Metal Film ◽  
Flow Line ◽  
Contact Pressure Distribution ◽  
Frictional Properties ◽  
Frictional Characteristic ◽  
The Coefficient Of Friction ◽  
Soft Metal ◽  
Flow Deformation

The frictional characteristic is examined with reference to a model considering the interference effect of plastic flow (deformation) in soft metal film, when a two-protuberance indentor is slid on a surface covered by electroplated soft metal film. The result is compared with that of a single-protuberance indentor. The coefficient of friction in a two-protuberance indentor, where the interference effect exists, is lower than in a single-protuberance indentor, where the interference effect does not. This fact can well be explained with the configuration of plastic flow line on protuberances described by deforming soft metal film, and the corresponding contact pressure distribution between protuberances and a surface.

Frictional Properties of a Surface Covered With Soft Metal Surface Film (Surface Topography and Frictional Properties)

1987 ◽  
Vol 109 (3) ◽  
pp. 545-551 ◽  
Author(s):  
Shinobu Kato ◽  
Etsuo Marui ◽  
Kiyoo Tachi
Keyword(s):  
Surface Topography ◽  
Metal Surface ◽  
Metal Film ◽  
Surface Film ◽  
Frictional Coefficient ◽  
Film Surface ◽  
Small Radius ◽  
Radius Of Curvature ◽  
Frictional Properties ◽  
Soft Metal

The friction between a real engineering surface composed of many micro-asperities and a surface covered with soft metal film is discussed. First, the frictional coefficient shows a remarkable load dependency, when a hard single protuberance with a small radius of curvature is slid on a soft metal surface. This load dependence originates from the ploughing effect induced by the cooperation of contact pressure and shearing resistance of the soft metal film deforming on the protuberance surface. Based on this result, the effect of the real engineering surface topography on the frictional properties is studied.

Paper 21: Variations in Friction and Wear between Unlubricated Steel Surfaces

1966 ◽  
Vol 181 (15) ◽  
pp. 16-24
Author(s):  
S. W. E. Earles ◽  
D. G. Powell
Keyword(s):  
Wear Rate ◽  
Mild Steel ◽  
Oxide Layer ◽  
Coefficient Of Friction ◽  
Surface Film ◽  
Frictional Heating ◽  
Subsequent Increase ◽  
Track Condition ◽  
The Coefficient Of Friction ◽  
Steel Disc

Experiments have been conducted in a normal atmosphere using a 0·25-in diameter mild-steel pin specimen sliding on a 10-in diameter mild-steel disc. The ranges of normal force and speed are 0·5–10·4 lbf and 20–190 ft/s respectively. Initially the coefficient of friction is comparatively large, and the wear is of the severe metallic form. However, frictional heating causes rapid oxidation of the surfaces and, if the sliding distance is sufficient, the eventual retention of an oxide layer causes a rapid decrease in the coefficient of friction and the wear rate decreases by 3–4 orders of magnitude. At speeds above about 75 ft/s and loads below about 5 lbf the formation, after several hours' sliding, of a continuous oxide layer on the track causes a further reduction in the pin wear rate. At higher loads and/or lower speeds this track condition is not attained. At speeds of 75 ft/s and above there exists a critical load (the magnitude of which depends on speed) above which periodic removals of the surface film(s) occur producing metallic wear and high friction. However, the subsequent increase in oxidation allows conditions of mild wear to be re-established generally within a few seconds. The steady-state coefficient of friction has been observed to be a function of load1/2 × speed, and periodic surface breakdowns found to occur when load1/2 × speed exceeds 170 lbf1/2 ft/s, the frequency decreasing with increasing load or speed.

The Influence of Surface Roughness on the Mechanism of Friction

1970 ◽  
Vol 92 (2) ◽  
pp. 264-272 ◽  
Author(s):  
T. Tsukizoe ◽  
T. Hisakado
Keyword(s):  
Surface Roughness ◽  
Metal Surface ◽  
Coefficient Of Friction ◽  
Dry Friction ◽  
Metal Surfaces ◽  
Roughness Effects ◽  
Real Area Of Contact ◽  
The Coefficient Of Friction ◽  
Tangential Forces ◽  
Soft Metal

A study was made of surface roughness effects on dry friction between two metals, assuming that the asperities are cones of the slopes which depend on the surface roughness. The theoretical explanations were offered for coefficients of friction of the hard cones and spheres ploughing along the soft metal surface. A comparison of calculated values based on these with experimental data shows good agreement. Moreover, theoretical discussion was carried out of surface roughness effects on dry friction between two metal surfaces on the basis of the analyses of the frictional mechanism for a hard slider on the metal surface. The theoretical estimation of the coefficient of friction between two metal surfaces can be carried out by using the relations between the surface roughness and the slopes of the asperities, and the coefficient of friction due to the adhesion at the interface. The experiments also showed that when two metal surfaces are first loaded normally and then subjected to gradually increasing tangential forces, real area of contact between them increases and the maximum tangential microslip of them increases with the increase of the surface roughness.

Correlating the Features of Topography to Friction by Sliding Experiments

2008 ◽  
Author(s):  
Anirudhan Pottirayil ◽  
Pradeep L. Menezes ◽  
Satish V. Kailas
Keyword(s):  
Sheet Metal ◽  
Coefficient Of Friction ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Work Piece ◽  
Manufacturing Processes ◽  
Experimental Procedure ◽  
The Coefficient Of Friction ◽  
Soft Metal

Friction can influence the quality of the finished product to a large extent in certain manufacturing processes. Sheet metal forming is a particular case, where the friction between the hard-die and the relatively soft work-piece can be extremely important. Under such conditions, topography of the harder surface can influence the resistance to traction at the interface. This paper discusses about the correlation between certain features of the surface topography and coefficient of friction based on experiments involving sliding of a few soft metal pins against a harder material. A brief description of the experimental procedure and the analysis are presented. A hybrid parameter which encapsulates both the amplitude features as well as the relative packing of peaks is shown to correlate well with the coefficient of friction.

scholarly journals The influence of temperature on boundary lubrication

1942 ◽  
Vol 181 (984) ◽  
pp. 23-42 ◽  
Keyword(s):  
Oleic Acid ◽  
Coefficient Of Friction ◽  
Boundary Lubrication ◽  
Surface Film ◽  
Adsorbed Layer ◽  
Surface Measurement ◽  
Polar Group ◽  
The Coefficient Of Friction ◽  
Low Speeds ◽  
Frictional Behaviour

The frictional behaviour between mild steel surfaces lubricated with excess of pure hydrocarbons, ketones, alcohols, amides, acids and esters has been investigated at low speeds and under high loads. In all cases a transition from smooth sliding to irregular stick and slip motion takes place at a temperature characteristic of the lubricant employed. Experiments in which lubricant films one or more molecules thick were built up by the Langmuir-Blodgett technique have shown that the transition from smooth sliding to stickslips occurs when the adsorbed surface film of lubricant breaks down and becomes disoriented. Acids and esters are shown to be strongly adsorbed, while hydrocarbons, ketones, alcohols and amides are not appreciably adsorbed. It is shown that adsorption of acids and esters occurs by the interaction of the dipoles in their polar group with the metal atoms in the surface. The results also suggest that molecules of long-chain compounds are oriented on a metal surface in the same way as they have been shown to be arranged on an aqueous surface. Measurement of the coefficient of friction between surfaces lubricated with films one and many molecules thick has shown that under conditions of ‘ boundary lubrication ’ prevailing at high loads and low speeds, excess of lubricant is squeezed out, and lubrication is effected by a unimolecular film adsorbed on each surface. The variation of the coefficient of friction with load in the case of oleic acid shows that orientation with this lubricant extends beyond the primary adsorbed layer. This result accounts for the low values of the coefficient of friction obtained by previous workers, and explains the good lubricating properties of oleic acid. These experiments show that a study of the frictional behaviour provides a m ethod of investigating the properties of surface films on metals.

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