Effect of Load and Temperature on the Tribological Characteristics of a Steel Pin on Polyoxymethylene Disk Interface

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Matthew G. Larson ◽  
Shannon J. Timpe
Keyword(s):  
Coefficient Of Friction ◽  
Thermal Energy ◽  
Skin Layer ◽  
Dynamic Friction ◽  
Injection Mold ◽  
Friction Mechanism ◽  
Disk Interface ◽  
Load Dependence ◽  
The Coefficient Of Friction ◽  
Initial Drop

The static and dynamic friction properties of a steel pin on polyoxymethelyne homopolymer disk were studied at temperatures ranging from 22 to 160 °C. Samples were tested at externally applied normal loads ranging from 20 to 80 N. Under this range of temperatures, the friction coefficients displayed a linearly increasing dependence on the load. The load dependence is attributed to an enhanced contribution of the plowing friction mechanism at higher loads. As load increases, the pin asperities penetrate into the hard, injection mold-induced skin layer, causing an increase in the frictional plowing. The coefficient of friction was observed to decrease from 0.08 at 22 °C to 0.05 at 50 °C, and subsequently rise to 0.07 at 160 °C. The initial drop was caused by a decrease in the modulus of elasticity attributed to the rise in molecular mobility with increased available thermal energy. As the temperature increased to 160 °C, however, the further decrease in modulus allowed the penetration of the pin asperities to increase significantly, requiring increased material displacement to initiate frictional motion.

Coefficients of Friction: Static Versus Dynamic

2020 ◽  
Author(s):  
Jack Youqin Huang
Keyword(s):  
Coefficient Of Friction ◽  
Frictional Force ◽  
Inertial Force ◽  
Static Friction ◽  
Theory And Practice ◽  
Dynamic Friction ◽  
Kinetic Friction ◽  
The Coefficient Of Friction ◽  
Static Versus Dynamic ◽  
New Discovery

Abstract This paper deals with the problem of static and dynamic (or kinetic) friction, namely the coefficients of friction for the two states. The coefficient of static friction is well known, and its theory and practice are commonly accepted by the academia and the industry. The coefficient of kinetic friction, however, has not fully been understood. The popular theory for the kinetic friction is that the coefficient of dynamic friction is smaller than the coefficient of static friction, by comparison of the forces applied in the two states. After studying the characteristics of the coefficient of friction, it is found that the comparison is not appropriate, because the inertial force was excluded. The new discovery in the paper is that coefficients of static friction and dynamic friction are identical. Wheel “locked” in wheel braking is further used to prove the conclusion. The key to cause confusions between the two coefficients of friction is the inertial force. In the measurement of the coefficient of static friction, the inertial force is initiated as soon as the testing object starts to move. Therefore, there are two forces acting against the movement of the object, the frictional force and the inertial force. But in the measurement of the coefficient of kinetic friction, no inertial force is involved because velocity must be kept constant.

A Theory of Dynamic Rubber Friction

1966 ◽  
Vol 39 (2) ◽  
pp. 320-327 ◽  
Author(s):  
A. Schallamach
Keyword(s):  
Coefficient Of Friction ◽  
Time Lag ◽  
Quantitative Agreement ◽  
Dynamic Friction ◽  
Average Life ◽  
Thermally Activated ◽  
Molecular Adhesion ◽  
Rubber Friction ◽  
The Coefficient Of Friction ◽  
Rate Processes

Abstract Assuming dynamic friction to arise from the shearing and subsequent breaking of distinct bonds between the rubbing members, a general equation is derived for the frictional force which involves the number and average life of the bonds as well as the average time lag between breaking and re-making of a bond at a given site. In the case of friction between rubber and smooth, hard surfaces, the bonds are attributed to local molecular adhesion between rubber and track, both formation and breaking of the bonds being thermally activated rate processes. A theory developed on this basis reproduces the experimental results obtained by Grosch in that the coefficient of friction as function of the velocity has a pronounced maximum. The height of the maximum and the velocity at which it occurs are in semi-quantitative agreement with Grosch's findings.

Anisotropic Frictional Behavior of Nanotextured Surfaces

2008 ◽  
Author(s):  
H.-S. Zhang ◽  
K. Komvopoulos
Keyword(s):  
Coefficient Of Friction ◽  
Normal Load ◽  
Ion Beam ◽  
Textured Surfaces ◽  
Friction Mechanism ◽  
Atomic Force ◽  
Afm Imaging ◽  
The Coefficient Of Friction ◽  
Tip Radius ◽  
Adhesion Friction

Silicon wafers were exposed to an oblique Ar+ ion beam to create arrays of surface ripples. Atomic force microscope (AFM) imaging revealed that the rippled (textured) surfaces exhibited highly anisotropic morphologies. Nanoscale friction experiments performed with different diamond tips illustrated a dependence of the coefficient of friction on tip radius, normal load, and sliding direction. Changes in the coefficient of friction are interpreted in terms of the applied normal load and varying contributions of the adhesion friction mechanism.

The Coefficients of Friction between Rubber and Other Materials. Frictional Grip of Rubber-Tired Wheels

1930 ◽  
Vol 3 (1) ◽  
pp. 67-73
Author(s):  
R. Ariano
Keyword(s):  
Coefficient Of Friction ◽  
Static Friction ◽  
Systematic Difference ◽  
Road Surface ◽  
Dynamic Friction ◽  
Simple Relationship ◽  
Inflation Pressure ◽  
The Coefficient Of Friction ◽  
Individual Design ◽  
Increasing Load

Abstract (i) The coefficients of friction (ƒI and ƒnI) of rubber tires on dry non-dusty surfaces are practically independent of the load on the wheel, and (with pneumatics) of the inflation pressure; on muddy surfaces the coefficients (especially ƒnI tend to decrease with increasing load. (ii) Dust, mud, or water reduces the friction with rubber tires, but not with iron tires. (iii) The tread pattern reduces the friction on dry surfaces, but increases it on muddy surfaces. (iv) There is no systematic difference between pneumatic, semi-pneumatic (cushion) and solid tires as regarda coefficient of friction; the details of individual design and material are the deciding factors; this is in agreement with the results of Bredtscheiner (Verkehrstechnik, 1922; see Schaar, “Die Beanspruchung der Strassen durch die Kraftfahrzeuge,” Zementverlag, 1925). (v) There is no simple relationship between the coefficient of friction and the compressibility or area of contact of the tire. (vi) The static friction perpendicular to the direction of travel is greater than in this direction. (vii) The coefficient of friction depends on the type of road surface, its de-formability, and especially on the presence or absence of dust, mud, or water. (viii) Rubber tires have a much higher coefficient of friction than iron tires, especially on dry hard surfaces. (ix) The static friction is 10 to 20 per cent higher than the dynamic friction.

Measurements of Grain Kernel Friction Coefficients Using a Reciprocating-Pin Tribometer

2020 ◽  
Vol 63 (3) ◽  
pp. 675-685 ◽  
Author(s):  
Zhengpu Chen ◽  
Carl Wassgren ◽  
Kingsly Ambrose
Keyword(s):  
Coefficient Of Friction ◽  
Particle Interaction ◽  
List Type ◽  
Dynamic Friction ◽  
Friction Coefficients ◽  
Particle Level ◽  
The Coefficient Of Friction ◽  
Wall Materials ◽  
Wall Interaction ◽  
Wheat Kernels

Highlights A tribometer was used to measure the friction coefficients of corn and wheat kernels. Both static and dynamic friction coefficients were measured for particle-wall interaction. Data analysis processes were developed to calculate dynamic friction coefficients for inter-particle interaction. Abstract. Various devices have been developed to measure the coefficient of friction (COF) of grain kernels; however, the majority of these tests measure the particle-wall COF at a bulk level. A method that can accurately measure both particle-wall and inter-particle COFs at a single-particle level remains to be developed. The objective of this study was to explore the feasibility of using a reciprocating-pin tribometer to measure static and dynamic COFs between grain kernels and between grain kernels and wall materials. In this study, the methodology of the test was developed, and representative data from the particle-wall and inter-particle friction tests were reported. It was found that the static COFs of corn-steel, corn-acrylic, wheat-steel, and wheat-acrylic are 0.24 ±0.05, 0.22 ±0.03, 0.32 ±0.02, and 0.29 ±0.03, respectively. The dynamic COFs of corn-steel, corn-acrylic, corn-corn, wheat-steel, wheat-acrylic, and wheat-wheat are 0.22 ±0.06, 0.16 ±0.01, 0.09 ±0.02, 0.30 ±0.02, 0.20 ±0.02, and 0.18 ±0.04, respectively. The current study demonstrates that the reciprocating-pin tribometer is suitable for measuring the particle-wall and inter-particle COFs of grain kernels. Keywords: Coefficient of friction, Grain kernel, Reciprocating-pin tribometer

scholarly journals Effect of Stick - Slip Phenomena between Human Skin and UHMW Polyethylene

2021 ◽  
Vol 29 (3) ◽  
Author(s):  
Emad Kamil Hussein ◽  
Kussay Ahmed Subhi ◽  
Tayser Sumer Gaaz
Keyword(s):  
Friction Coefficient ◽  
Human Skin ◽  
Coefficient Of Friction ◽  
Normal Load ◽  
Static Friction ◽  
Time Interval ◽  
Dynamic Friction ◽  
Sliding Velocity ◽  
Stick Slip ◽  
The Coefficient Of Friction

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.

A Methodology for the Simulation of Surface-Contact Grinding Tool Topography

2009 ◽  
Vol 416 ◽  
pp. 519-523
Author(s):  
Guo Zhi Zhang ◽  
Xian Hua Zhang ◽  
Li Li Liu ◽  
Zeng Ju Wei
Keyword(s):  
Finite Element ◽  
Theoretical Model ◽  
Finite Element Model ◽  
Coefficient Of Friction ◽  
Surface Friction ◽  
Static Friction ◽  
Element Model ◽  
Friction Mechanism ◽  
Manufacturing Quality ◽  
The Coefficient Of Friction

Study on the effect of the surface manufacturing quality (roughness) to the friction between the surfaces. Based on the plastic theory of mechanism-based strain gradient (MSG) of the micro-plastic-mechanics and the contact theory, the theoretical model of the coefficient of friction between the rough surfaces and the non-linear finite element model between the grinding samples were established. Moreover, the surface stress distribution and the coefficient of friction were obtained through the sub-structure finite element method. The established model of static friction theoretical model and the accuracy of the finite element model were verified through comparing with the result of the static friction experiments between the grinding samples with different surface manufacturing quality. The study in the paper is important to the study on the surface friction mechanism.

Static and Dynamic Friction Characteristics of a Steel on Polyoxymethylene Interface Under Dry and Lubricated Contact Conditions

2014 ◽  
Author(s):  
Matthew G. Larson ◽  
Shannon J. Timpe
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Skin Layer ◽  
Dynamic Friction ◽  
Disk System ◽  
Friction Mechanism ◽  
Contact Conditions ◽  
Friction Coefficients ◽  
Friction Characteristics ◽  
Lubrication Regime ◽  
Dry Contact

The static and dynamic friction characteristics of a steel pin on injection molded polyoxymethylene homopolymer disk system were studied under both lubricated and dry contact conditions. Samples were tested at externally-applied normal loads ranging from 20 to 160 N. Under dry test conditions, friction coefficients displayed two distinct regions with very low friction coefficients at low loads and rising to approximately 0.7 (static) and 0.6 (dynamic) at loads above 60N. This phenomenon is attributed to an enhanced contribution of the ploughing friction mechanism at higher loads. As load increases, the pin penetrates through the injection mold-induced skin layer and into the core. At loads lower than 60 N, however, the pin does not significantly penetrate the disk during the test and the adhesive mechanism dominates the tribological properties. Additional tests were performed in order to determine the effects of a lithium soap thickened, low viscosity, synthetic hydrocarbon grease. The average static and dynamic friction coefficients for the lubricated interface were found to be 0.031 ± 0.01 and 0.027 ± 0.01, respectively. The friction coefficients exhibited a linear dependence on the load. This result indicates a shift from the more optimal elastohydrodynamic lubrication regime at lower loads to a mixed lubrication regime and a behavior closer to dry contact at higher loads. Results are interpreted in light of the principal static and dynamic friction mechanisms.

The Dependency of Takeoff Velocity and Friction on Head Geometry and Drive Configuration

1995 ◽  
Vol 117 (2) ◽  
pp. 350-357 ◽  
Author(s):  
Jerry J. K. Lee ◽  
J. Enguero ◽  
M. Smallen ◽  
A. Chao ◽  
E. Cha
Keyword(s):  
Thin Film ◽  
Coefficient Of Friction ◽  
Air Bearing ◽  
Head Disk Interface ◽  
Skew Angle ◽  
Lower Mass ◽  
Frictional Drag ◽  
Disk Interface ◽  
The Coefficient Of Friction ◽  
Sliding Distance

Wear at the head-disk interface of magnetic recording devices is dependent on the contact sliding distance between the head and disk. The sliding distance is dependent on the head takeoff velocity and frictional drag. In this study, the dependence of takeoff velocity and friction on selected head parameters was measured with an air bearing spindle equipped with a strain gauge. For the thin film head, crown had the greatest influence on takeoff velocity, followed by bolt pattern runout, suspension preload, camber, skew angle, and rail width in decreasing order. For the metal-ingap head, ski jump had the greatest influence. The rest of the parameters followed in the same order as they did for the thin film head. Twist and edge blend did not affect takeoff velocity, but larger edge blends did improve contact start-stop performance. Lower mass disk stacks did better in contact start-stop tests because of their shorter sliding distance before reaching the takeoff velocity or after achieving the landing velocity. Finally, both crown and skew angle affected the coefficient of friction between the head and disk. Heads with a more positive crown or zero skew angle had the lowest coefficient of friction.

Sign in / Sign up

Export Citation Format

Share Document