Experimental study on the coefficient of friction of the ball screw

2021 ◽  
pp. 1-18
Author(s):  
Lu-Chao Zhang ◽  
Chang-Guang Zhou
Keyword(s):  
Experimental Study ◽  
Coefficient Of Friction ◽  
Hydrodynamic Lubrication ◽  
Friction Torque ◽  
Measuring System ◽  
Ball Screw ◽  
Stribeck Curve ◽  
Key Factor ◽  
The Coefficient Of Friction ◽  
Curve Fitting Method

Abstract The coefficient of friction (COF) is a key factor to estimate the performance of ball screws. Pieces of research focus on the experimental study of the COF, leading to the COF chosen empirically in many studies. To acquire the COF of the HJG-4010, a measuring system is conducted to detect the friction torque under different preloads and rotational speeds and the effects of the applied axial load and rotational speed on the COF are analyzed. By the curve fitting method, the Stribeck curve of the ball screw is obtained. The experimental results show that the lubricating state can be divided into two categories: the mixed lubrication state, and the hydrodynamic lubrication state. This study is beneficial to choose a suitable working condition for a different performance of the ball screw.

Skin-skin contact: The normal-force dependence of the coefficient of friction between a bare finger and artificial skin changes randomly

2021 ◽  
Author(s):  
Koki Inoue ◽  
Shogo Okamoto ◽  
Yasuhiro Akiyama ◽  
Yoji Yamada
Keyword(s):  
Experimental Study ◽  
Coefficient Of Friction ◽  
Normal Force ◽  
Skin Surface ◽  
Artificial Skin ◽  
Skin Changes ◽  
Root Cause ◽  
Skin Contact ◽  
The Coefficient Of Friction ◽  
Frictional Forces

Abstract This study investigates the dependence of the coefficients of friction on the normal force produced by sliding a bare finger over different artificial skins with seven levels of hardness. The coefficient of friction was modeled as a power function of the normal force. An experimental study that involved sliding a finger over artificial skin surfaces was carried out under two conditions: the fingertip being wiped by a dry cloth or a cloth soaked in ethanol. Although the exponential term was assumed to be nearly constant for identical tribological conditions, we observed that the exponent varied randomly and could be negative, zero, or positive. This probabilistic behavior has not been explicitly analyzed in previous studies on human fingertips. The probability density function of the exponent depended on the moisture content of the finger. The exponent was either nearly zero or positive when the finger sliding on the skin surface was wiped with an alcohol-soaked cloth and dried. These findings play an important role in analyzing the frictional forces produced during skin–skin contact in terms of determining the root cause behind the random variations in the dependence of the coefficient of friction on the normal force.

Tribometer for Dry Friction Measurement

1999 ◽  
Author(s):  
Marc Brandl ◽  
Friedrich Pfeiffer
Keyword(s):  
Coefficient Of Friction ◽  
Dry Friction ◽  
Stribeck Curve ◽  
Body System ◽  
Friction Measurement ◽  
Detailed Model ◽  
The Coefficient Of Friction ◽  
Simulation Results ◽  
Multi Body

Abstract This paper deals with the measurement of dry friction. A tribometer was developed in order to identify both the sticking and the sliding coefficient of friction. The aim was to determine the so called Stribeck-curve of any material in contact. The design of the plant is presented. Avoiding errors in recalculating the coefficient of friction, a detailed model of the plant as a multi body system with motor feedback was generated. Advantages of the tribometer are shown in simulations. Some results of measurements in comparison with simulation results are presented.

Influence of Hydrodynamic Fluid Pressure and Shoe Tread Depth on Available Coefficient of Friction

2012 ◽  
Author(s):  
Gurjeet Singh ◽  
Kurt Beschorner
Keyword(s):  
Coefficient Of Friction ◽  
Hydrodynamic Lubrication ◽  
Fluid Pressure ◽  
Hydrodynamic Pressure ◽  
High Viscosity ◽  
Health Concern ◽  
Fluid Viscosity ◽  
Low Viscosity ◽  
The Coefficient Of Friction ◽  
Lubrication Mechanisms

Slip and fall accidents are a major occupational health concern. Identifying the lubrication mechanisms affecting shoe-floor-contaminant friction under biofidelic (testing conditions that mimic human slipping) conditions is critical to identifying unsafe surfaces and designing a slip-resistant work environment. The purpose of this study is to measure the effects of varying tread design, tread depth and fluid viscosity on underfoot hydrodynamic pressure, the load supported by the fluid (i.e. load carrying capacity), and the coefficient of friction (COF) during a simulated slip. A single vinyl floor material and two shoe types (work shoe and sportswear shoe) with three different tread depths (no tread, half tread and full tread) were tested under two lubrication conditions: 1) 90% glycerol and 10% water (219 cP) and 2) 1.5% Detergent-98.5% (1.8cP) water solutions. Hydrodynamic pressures were measured with a fluid pressure sensor embedded in the floor and a forceplate was used to measure the friction and normal forces used to calculate coefficient of friction. The study showed that hydrodynamic pressure developed when high viscosity fluids were combined with no tread and resulted in a major reduction of COF (0.005). Peak hydrodynamic pressures (and load supported by the fluid) for the no tread-high viscous conditions were 234 kPa (200.5 N) and 87.63 kPa (113.3 N) for the work and sportswear shoe, respectively. Hydrodynamic pressures were negligible when at least half the tread was present or when a low viscosity fluid was used despite the fact that many of these conditions also resulted in dangerously low COF values. The study suggests that hydrodynamic lubrication is only relevant when high viscous fluids are combined with little or no tread and that other lubrication mechanisms besides hydrodynamic effects are relevant to slipping like boundary lubrication.

Hydrodynamic Lubrication of a Porous Slider

1973 ◽  
Vol 15 (3) ◽  
pp. 232-234 ◽  
Author(s):  
J. Prakash ◽  
S. K. Vij
Keyword(s):  
Drag Coefficient ◽  
Closed Form ◽  
Coefficient Of Friction ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Centre Of Pressure ◽  
Slider Bearing ◽  
Frictional Drag ◽  
Pressure Load ◽  
The Coefficient Of Friction

A plane porous slider bearing is analysed and closed form expressions for pressure, load, frictional drag, coefficient of friction and centre of pressure are obtained. The effect of porosity is to decrease the load capacity and friction. However, the coefficient of friction is increased.

Determination of Tire-Road Friction Coefficients for Skid Mark Analysis

1985 ◽  
Vol 13 (1) ◽  
pp. 41-64
Author(s):  
W. R. Garrott ◽  
D. A. Guenther
Keyword(s):  
Experimental Study ◽  
Coefficient Of Friction ◽  
Friction Coefficients ◽  
Pickup Truck ◽  
The Road ◽  
Heavy Trucks ◽  
Road Friction ◽  
Brake Application ◽  
The Coefficient Of Friction

Abstract An experimental study was made to compare the validities of methods currently used by accident reconstructionists to determine the coefficient of friction between the road and the vehicle tires at the time of an incident. This value could then be used in conjunction with skid mark length and vehicle weight to calculate the prebraking speed of the vehicle. Three automobiles and three trucks with a variety of tires and loadings were used on a variety of pavements. The accuracy and area of applicability of each of four methods for obtaining friction coefficients were determined by relating the prebraking speed calculated from each to the actual speed at the time of brake application. All four methods were satisfactory for automobiles and the pickup truck used, but only two were acceptable for heavy trucks. The most valid coefficients are obtained from skid mark lengths obtained under conditions duplicating those in an incident.

Experimental Study on Powder Suppression Characteristics of Autoclaved Brick

2013 ◽  
Vol 773 ◽  
pp. 272-277
Author(s):  
Wei Zhang ◽  
Yan Yan Zhang ◽  
Fan Zhu
Keyword(s):  
Experimental Study ◽  
Coefficient Of Friction ◽  
Lateral Pressure ◽  
Powder Compaction ◽  
Compression Rate ◽  
The Coefficient Of Friction ◽  
Pressing Technology

The curves of cylinder displacement and pressure can be obtained through the wall brick press autoclaved brick experiment, which can determine the powder compaction equation, including suppression, friction and the characteristics of stripping, modify Kawakita equation, and improve the calculation precision, get the product of the coefficient of friction and lateral pressure and its variation law with compression rate; .in order to provide the basis for the design of pressure machine and mould and optimization of pressing technology

scholarly journals Application of topological optimisation methodology to hydrodynamic thrust bearings

2020 ◽  
pp. 135065012097259
Author(s):  
Kalle Kalliorinne ◽  
Roland Larsson ◽  
Andreas Almqvist
Keyword(s):  
Coefficient Of Friction ◽  
Carrying Capacity ◽  
Friction Torque ◽  
Shape Optimisation ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Aspect Ratios ◽  
Load Carrying ◽  
The Coefficient Of Friction ◽  
Moving Asymptotes

The bearing geometry has a big impact on the performance of a hydrodynamic thrust bearing. For this reason, shape optimisation of the bearing surface has been carried out for some time, with Lord Rayleigh’s early publication dated back to 1918. There are several recent results e.g. optimal bearing geometries that maximise the load carrying capacity for hydrodynamic thrust bearings. Currently, many engineers are making an effort to include sustainability in their work, which increases the need for bearings with lower friction and higher load carrying capacity. Improving these two qualities will result in lower energy consumption and increase the lifetime of applications, which are outcomes that will contribute to a sustainable future. For this reason, there is a need to find geometries that have performance characteristics of as low coefficient of friction torque as possible. In this work, the topological optimisation method of moving asymptotes is employed to optimise bearing geometries with the objective of minimising the coefficient of friction torque. The results are both optimised bearing geometries that minimise the coefficient of friction torque and bearing geometries that maximise the load carrying capacity. The bearing geometries are of comparable aspect ratios to the ones uses in recent publications. The present article also covers minimisation of friction torque on ring bearing geometries, also known as thrust washers. The results are thrust washers with periodical geometries, where the number of periodical segments has a high impact on the geometrical outcome.

Experimental Study on Superlubricity of Ag Nanometer-Thick Layers by Sliding on a Macroscopic System

2005 ◽  
Author(s):  
Minoru Goto ◽  
F. Honda ◽  
T. Nakahara
Keyword(s):  
Experimental Study ◽  
Coefficient Of Friction ◽  
Network Structure ◽  
Scale Up ◽  
Film Morphology ◽  
Macroscopic System ◽  
The Coefficient Of Friction ◽  
Thick Layers ◽  
Plate Type ◽  
Ag Film

The experimental study on the Ag film was carried out using a diamond pin-on-plate type tribometer under ultrahigh vacuum (UHV) conditions. The coefficient of friction varied with the film morphology in nanometric scale up to 170 nm, and superlubricity as minimum coefficient of friction 0.007 was obtained on 5-nm Ag film with network structure. RHEED and STM observation of the film showed that the film morphologies changed drastically during rubbing, and that the superlubricity of this system is attributed to the lamella gliding of Ag (111) sheets.

Paper 4: An Experimental Study of the Frictional Behaviour of Steels at Elevated Temperatures

1966 ◽  
Vol 181 (15) ◽  
pp. 1-10
Author(s):  
L. A. Mitchell ◽  
T. S. Crawford
Keyword(s):  
Experimental Study ◽  
Coefficient Of Friction ◽  
Elevated Temperatures ◽  
Oxide Films ◽  
Hardened Steel ◽  
Material Combination ◽  
Severe Wear ◽  
Mild Wear ◽  
The Coefficient Of Friction ◽  
Frictional Behaviour

Many investigators, by the manner of presentation of results, have implied that for any given material combination and atmosphere, the coefficient of friction is a function of temperature alone. Experiments are described which were designed to evaluate the importance of the sliding and temperature histories on the unlubricated sliding performance of steels at temperatures up to 500°C. Only for a hardened steel, when mild wear prevailed, was the specimen history unimportant, and, in this case, μ was virtually independent of temperature. With materials exhibiting severe wear, sliding produced changes in friction which were attributed to hardening of the surfaces and when the thickness of oxide films became comparable with the size of transferred particles, exposure to temperature could modify subsequent frictional behaviour.

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