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Article
Publication date: 3 February 2012

Yan Yin, Jiusheng Bao and Lei Yang

The purpose of this paper is to find the variations of brake lining's frictional performance with braking conditions, and their influence on the braking safety and…

Abstract

Purpose

The purpose of this paper is to find the variations of brake lining's frictional performance with braking conditions, and their influence on the braking safety and reliability of automobiles.

Design/methodology/approach

As the semimetal brake lining is widely used currently in automobiles, it was selected as the experimental material. By simulating the braking conditions and environment of automobiles, some tribological experiments of the brake lining were investigated on the X‐DM friction tester, when it is paired with the friction disc made of gray cast iron. The influence of braking pressure, sliding velocity and surface temperature on the friction coefficient and its stability coefficient were studied in depth through experiments.

Findings

The friction coefficient decreases gradually with the increasing of braking pressure and sliding velocity when the surface temperature is naturally rising. It rises first then falls with the surface temperature rising and the maximal value appears at nearly 200°C. The stability of friction coefficient decreases obviously when the sliding velocity exceeds 30 m/s, the braking pressure exceeds 1.8 MPa and the surface temperature is over 200°C. Based on the experimental results, the authors consider that it is not reliable to execute an emergency braking only by rising the braking pressure when the automobile is driving with a high velocity. In order to reduce the bad influence of high temperature on frictional performance, some effective actions should be taken for cooling the friction disc. What is more, special attention should be paid to the decreasing of frictional stability during the braking with high velocity, pressure and temperature.

Originality/value

This paper studies the influence of braking conditions on friction coefficient and its stability of the semimetal brake lining for automobiles. It is believed that this research may have some actual guidance for enhancing the braking safety and reliability of automobiles.

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Article
Publication date: 25 September 2009

Bao Jiusheng, Zhu Zhencai, Yin Yan and Chen Guoan

The purpose of this paper is to find the influence of the initial braking velocity and braking frequency on the tribological performance of the non‐asbestos brake shoe…

Abstract

Purpose

The purpose of this paper is to find the influence of the initial braking velocity and braking frequency on the tribological performance of the non‐asbestos brake shoe used in mine hoisters during some continuous emergency brakings.

Design/methodology/approach

The tribological performance experiments of the WSM‐3 non‐asbestos brake shoe braking on the 16 Mn steel are investigated on the X‐DM friction tester, by simulating continuous emergency brakings of a mine hoister ten times. Three kinds of tribological indexes: friction coefficient, its stability coefficient, and wearing rate are considered to score the tribological performance of the brake shoe.

Findings

When the initial braking velocity increases, the mean friction coefficient of the brake shoe decreases at first, then rises, and falls again finally. But when the braking frequency exceeds seven times, the falling process of the friction coefficient at low‐velocity period does not appear again. Second, when the initial braking velocity is no higher than 10 m/s, the mean friction coefficient rises with the braking frequency increasing. But when the velocity exceeds 10 m/s, the mean friction coefficient rises with the braking frequency increasing at first, then falls. Third, when the initial braking velocity is no higher than 12.5 m/s, the friction coefficient of the brake shoe has quite a favorable stability with the coefficient is no bigger than 75 percent. But when the velocity exceeds 12.5 m/s, the stability of the friction coefficient is diminishing obviously. Fourth, the wearing rate of the brake shoe increases quickly, during the process that the velocity rising from 10 to 12.5 m/s, but increases much more slowly after that period.

Originality/value

The paper investigates the tribological performance of the WSM‐3 non‐asbestos brake shoe during some continuous emergency brakings and finds that, when the initial braking velocity is no higher than 12.5 m/s and the braking frequency is no more than seven times, the WSM‐3 non‐asbestos brake shoe has quite a high friction coefficient, a good friction stability, and a low‐wearing rate, which indicate that it is very appropriate for using in the disk brake of mine hoisters in China.

Details

Industrial Lubrication and Tribology, vol. 61 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 4 March 2014

Yanzhong Wang, Bin Wei, Keyan Ning and Ming Han

This research investigated the mechanism of wet friction plates of engagement and solved the problem that the lock-up friction coefficient of sinter material could not be…

Abstract

Purpose

This research investigated the mechanism of wet friction plates of engagement and solved the problem that the lock-up friction coefficient of sinter material could not be obtained but from experiments for a long time. The paper aims to discuss these issues.

Design/methodology/approach

Including four steps: surface topology sampling and reconstruction, fractal parameters obtaining and fractal surface simulating, micro-contact mechanics model and friction coefficient fractal model, and experimental verification.

Findings

After running in stage of the friction plates, the fractal dimension would reach a dynamically stable stage for a long time. The proportional coefficient K expresses the correlation between the base hardness and the asperities shear strength. The model could be property for one or more working condition via adjusting the coefficient K. The experiment data of friction coefficient are increased as the load magnified both in the model prediction and experiment practice. The trend is different from other models.

Originality/value

This research is original and it is supported by national defense project. It would be served for tracked vehicles to solve the defect in transmission system. The friction coefficient is obtained via solving the tangential force in MB model. The surface topography could be reconstructed by laser topography instrument and the parameters could be received by program.

Details

Industrial Lubrication and Tribology, vol. 66 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 July 2005

Mary E. Kinsella, Blaine Lilly, Benjamin E. Gardner and Nick J. Jacobs

To determine static friction coefficients between rapid tooled materials and thermoplastic materials to better understand ejection force requirements for the injection…

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Abstract

Purpose

To determine static friction coefficients between rapid tooled materials and thermoplastic materials to better understand ejection force requirements for the injection molding process using rapid‐tooled mold inserts.

Design/methodology/approach

Static coefficients of friction were determined for semi‐crystalline high‐density polyethylene (HDPE) and amorphous high‐impact polystyrene (HIPS) against two rapid tooling materials, sintered steel with bronze (LaserForm ST‐100) and stereolithography resin (SL5170), and against P‐20 mold steel. Friction tests, using the ASTM D 1894 standard, were run for all material pairs at room temperature, at typical part ejection temperatures, and at ejection temperatures preceded by processing temperatures. The tests at high temperature were designed to simulate injection molding process conditions.

Findings

The friction coefficients for HDPE were similar on P‐20 Steel, LaserForm ST‐100, and SL5170 Resin at all temperature conditions. The HIPS coefficients, however, varied significantly among tooling materials in heated tests. Both polymers showed highest coefficients on SL5170 Resin at all temperature conditions. Friction coefficients were especially high for HIPS on the SL5170 Resin tooling material.

Research limitations/implications

Applications of these findings must consider that elevated temperature tests more closely simulated the injection‐molding environment, but did not exactly duplicate it.

Practical implications

The data obtained from these tests allow for more accurate determination of friction conditions and ejection forces, which can improve future design of injection molds using rapid tooling technologies.

Originality/value

This work provides previously unavailable friction data for two common thermoplastics against two rapid tooling materials and one steel tooling material, and under conditions that more closely simulate the injection‐molding environment.

Details

Rapid Prototyping Journal, vol. 11 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 15 June 2012

Jiusheng Bao, Zhencai Zhu, Minming Tong, Yan Yin and Yuxing Peng

The purpose of this paper is to describe some tribological experiments which were executed to find the influence of braking pressure on tribological performance of…

Abstract

Purpose

The purpose of this paper is to describe some tribological experiments which were executed to find the influence of braking pressure on tribological performance of non‐asbestos brake shoe used in mine hoister during its emergency braking.

Design/methodology/approach

The WSM‐3 non‐asbestos brake shoe, which has been widely used in mine hoister, was selected as experimental material. Some tribological experiments of the brake shoe sliding on 16Mn steel were investigated on the X‐DM friction tester by simulating of emergency braking conditions of mine hoister. Three kinds of tribological indexes: friction coefficient, stability coefficient of friction coefficient, and wear rate were considered to score the tribological performance and the morphology of worn surfaces were observed through the S‐3000N scanning electron microscopy (SEM) to explore the tribological mechanisms.

Findings

It was found first, that the instant friction coefficient is not constant during emergency braking. After a short climbing period, it rises gradually to steady value. Second, with the increasing of braking pressure, the mean friction coefficient rises first then falls, while its stability coefficient falls gradually. The wear rate rises continuously with the braking pressure increasing. Also, the rising velocity of wear rate at high pressure is higher than it is at low pressure. Third, the instant surface temperature rises first then falls during braking and the mean surface temperature rises continuously with the braking pressure increasing.

Originality/value

It is found that the increasing of braking pressure within a certain range is helpful for achieving a high friction coefficient and a steady wear rate. But too high pressure will cause contrarily the falling of frictional performance and serious of wear performance. So it is not reliable to rise the braking pressure without limited during emergency braking.

Details

Industrial Lubrication and Tribology, vol. 64 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 4 March 2020

Hua Zhang, Guangwu Zhou, Ping Zhong, Kepeng Wu and Xingwu Ding

The purpose of this paper is to study the influence of friction coefficient of materials with different elastic modulus on the variation of velocity and load under water…

Abstract

Purpose

The purpose of this paper is to study the influence of friction coefficient of materials with different elastic modulus on the variation of velocity and load under water lubrication and oil lubrication conditions.

Design/methodology/approach

Low-viscosity lubricating oil and water were used as lubricants to test the friction performance of the ball-disc contact friction pair in the lubrication state on the universal micro-tribometer multi-functional friction and wear test system.

Findings

In the same speed range, the lubrication states from soft to rigid materials are not necessarily similar to each other. Generally, the material with low elastic modulus is suitable in low-viscosity lubricant environments, while the material with high elastic modulus has relatively smaller friction coefficients in oil-lubricated environments compared with water lubrication. However, the coefficients of polyethylene, polytetrafluoroethylen and polyoxymethylene are exceeded by rubber’s coefficients under water lubrication in the same experiment environments, and their lubrication states are not affected by lubricants. The friction coefficient of the friction pair decreases with the increase of loads; however, it does not apply to all materials. The friction coefficients of materials with smaller elastic modulus such as rubber under high loads are rather large. Therefore, the elastic modulus of the material under high loads is a factor to be considered.

Originality/value

The Stribeck curves study of the ball-disk contact friction pair comprising soft and rigid materials, whose elastic modulus is from hundreds of GPa to a few of MPa, was carried out. The influence of different speeds, loads and lubricants on the friction coefficient of the friction pair was revealed, which provided a research basis for the selection and matching of friction pair materials.

Details

Industrial Lubrication and Tribology, vol. 72 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 24 January 2020

Jin Oh Chung, Sang Ryul Go, Hee Bum Choi and Tae Kwan Son

This paper aims to investigate the temperature dependence of transfer film formation and friction coefficients in NAO friction materials with four different abrasive…

Abstract

Purpose

This paper aims to investigate the temperature dependence of transfer film formation and friction coefficients in NAO friction materials with four different abrasive components, ZrO2, ZrSiO4, Al2O3 and Fe3O4.

Design/methodology/approach

8.5% SnS2 was added as a lubricating component to friction materials. Friction tests comprised 100 times of consecutive braking application for each friction material under constant temperature of 300°C, 400°C, 500°C and 600°C. After the friction tests, the friction surfaces of the counterpart disks were examined by scanning electron microscope to access the formation of transfer film.

Findings

Coefficients of friction depended on not only friction temperature but also friction history which is related to development of transfer film. The effect of the transfer film formation was to reduce the friction coefficients for most friction materials. Quantities of the transfer film formation varied with friction materials; at low temperature below 400° the transfer film formation was most active in the Fe3O4 materials, while at 600° it was the most active in the Al2O3 material. The effect of the lubricating component SnS2 was to suppress the formation of transfer film, thus enhancing friction coefficients.

Social implications

The enhancement of friction coefficients with addition of small amount of lubricating components such as SnS2 is expected to open a new approach in developing high performance-brake pads.

Originality/value

Temperature was the controlling parameter in the present test. Under these test modes, transfer film could be fully developed to access the role of the transfer film.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0427/

Details

Industrial Lubrication and Tribology, vol. 72 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 26 November 2018

Xiaogang Zhang and Yali Zhang

This study aims to investigate the sliding friction behaviour and mechanism of engineering surfaces.

Abstract

Purpose

This study aims to investigate the sliding friction behaviour and mechanism of engineering surfaces.

Design/methodology/approach

A new numerical approach is proposed. This approach derives the macroscale friction coefficient from microscale asperity interactions. By applying this approach, the sliding friction behaviour under different operating conditions were investigated in terms of molecular and mechanical components.

Findings

Numerical results demonstrate an independent relationship between normal load and friction coefficient, which is governed by the saturated plastic ratio. Numerical results also demonstrate that under very small load, an increase in load increases the friction coefficient. In addition, numerical results confirm the existence of optimal surface roughness where the friction coefficient is the lowest. For the surface profiles used in the current calculation, an optimal surface roughness value is obtained as Rq = 0.125 μm.

Originality/value

This new approach characterizes the deterministic relationship between macroscale friction coefficient and microscale asperity molecular/mechanical interactions. Numerical results facilitate the understanding of sliding friction mechanism.

Details

Industrial Lubrication and Tribology, vol. 71 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 9 September 2021

Rama Krishna S. and Patta Lokanadham

The purpose of the present paper aims to, study the coefficient of friction and wear behavior of nickel based super alloys used in manufacturing of gas and steam turbine…

Abstract

Purpose

The purpose of the present paper aims to, study the coefficient of friction and wear behavior of nickel based super alloys used in manufacturing of gas and steam turbine blades. In present paper, parametric study focuses on normal load, dry sliding velocity and contact temperature influence on coefficient of friction and wear of a nickel based super alloy material.

Design/methodology/approach

Experimental investigation is carried out to know the effect of varying load at constant sliding velocity and varying sliding velocity at constant load on coefficient of friction and wear behavior of nickel based super alloy material. The experiments are carried out on a nickel based super alloy material using pin on disk apparatus by load ranging from 30 N to 90 N and sliding velocity from 1.34 m/s to 2.67 m/s. The contact temperature between pin and disk is measured using K-type thermocouple for all test conditions to know effect of contact temperature on coefficient of friction and wear behavior of nickel based super alloy material. Analytical calculations are carried out to find wear rate and wear coefficient of the test specimen and are compared with experimental results for validation of experimental setup. Regression equations are generated from experimental results to estimate coefficient of friction and wear in the range of test conditions.

Findings

From the experimental results, it is observed that by increasing the normal load or sliding velocity, the contact temperature between the pin and disk increases, the coefficient of friction decreases and wear increases. Analysis of variance (ANOVA) is used to study the influence of individual parameters like normal load, dry sliding speed and sliding distance on the coefficient of friction and wear of nickel based super alloy material.

Originality/value

This is the first time to study effect of contact temperature on the coefficient of friction and wear behavior of nickel-based super alloy used for gas and steam turbine blades. Separate regression equations have been developed to determine the coefficient of friction and wear for the entire range of speed of gas turbine blades made of nickel based super alloy. The regression equations are also validated against experimental results.

Details

World Journal of Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 8 January 2018

Jiusheng Bao, Yan Yin, Lijian Lu and Tonggang Liu

The purpose of this study is to establish an effective method for characterizing the tribological properties of friction brakes during continuous braking because they have…

Abstract

Purpose

The purpose of this study is to establish an effective method for characterizing the tribological properties of friction brakes during continuous braking because they have direct influences on the reliable operation of transport vehicles and industrial equipments.

Design/methodology/approach

First, tribological tests were carried out with the X-DM type friction tester, and changing curves of friction coefficient and temperature were obtained. Second, a novel tribological characteristic parameter set characterizing the tribological properties of brake pair in continuous braking was extracted from some important experimental data such as friction coefficient, wear rate and temperature. Finally, the influence of law and mechanism of braking number on dynamic tribological parameters was studied through continuous braking experiments.

Findings

The extracted tribological characteristic parameter set includes two subsets: dynamic characteristic parameter subset and overall characteristic parameter subset, which is composed of ten parameters: dynamic parameters of friction coefficient (including average, trend coefficient and stability coefficient), dynamic wear rate, dynamic average temperature, dynamic temperature rise, overall average friction coefficient, overall wear rate, overall average temperature and overall temperature rise.

Originality/value

Conclusively, the novel tribological characteristic parameter set is more comprehensive and objective, and it can provide a theoretical basis for the study of tribological properties in continuous braking.

Details

Industrial Lubrication and Tribology, vol. 70 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

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