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Article
Publication date: 21 June 2011

Rukiye Ertan and Nurettin Yavuz

The purpose of this paper is to investigate the role of solid lubricants (graphite, coke, ZnS) on brake performance.

Abstract

Purpose

The purpose of this paper is to investigate the role of solid lubricants (graphite, coke, ZnS) on brake performance.

Design/methodology/approach

In this study, the tribological and surface characteristic of non‐asbestos organic type brake friction materials containing three different solid lubricants (graphite, coke, and ZnS) in different proportions were examined and evaluated experimentally. The coefficient of friction (COF) and wear behavior of the samples were tested on a chase‐type friction tester, and particular emphases were given to the effect of temperature and number of braking cycles on the COF. Each of the lubricants was added to the mixtures in different amounts and seven different brake linings were manufactured, provided that the total amount of solid lubricants and other ingredients were not changed. The worn surfaces of the specimens were analyzed using a scanning electron microscope with energy‐dispersive X‐ray microanalysis.

Findings

The experimental results indicate that graphite has a positive effect on the tribological properties of brake linings. However, brake linings containing higher concentrations of ZnS and coke showed an unstable friction coefficient relationship with the temperature and number of braking cycles. The formation of friction layers was detected on the friction surface of these samples, which indicates that an increase in coke and ZnS content increases the discontinuous and unstable friction film areas.

Originality/value

This paper fulfils the effects of solid lubricants (graphite, coke, ZnS) in brake friction materials with detailed tests and analysis.

Details

Industrial Lubrication and Tribology, vol. 63 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

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 used in…

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

Keywords

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 reliability of…

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.

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 non‐asbestos…

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

Keywords

Article
Publication date: 14 June 2013

Zhencai Zhu, Jiusheng Bao, Yan Yin and Guoan Chen

In order to improve the braking safety of mine hoisters, this paper aims to focus on the continuous repetitious emergency braking conditions to investigate an abnormal frictional…

Abstract

Purpose

In order to improve the braking safety of mine hoisters, this paper aims to focus on the continuous repetitious emergency braking conditions to investigate an abnormal frictional phenomena called “Frictional catastrophe (FC)” and its mechanisms.

Design/methodology/approach

The non‐asbestos brake shoe of a mine hoister was selected as frictional material and its paring material is 16Mn steel. The tribological properties of the brake shoe were tested on the pad‐on‐disc friction tester by the simulation of continuous emergency braking conditions. The thermal analysis experiments, the temperature field simulations and the SEM analysis of the brake shoe were accomplished to reveal the mechanisms of the FC.

Findings

It was found that the friction coefficient of the brake shoe sometimes falls suddenly during braking. This abnormal frictional phenomena is called “Frictional catastrophe (FC)”. It is considered that the friction heat, which is accumulated rapidly by the braking on the surface of the brake shoe, makes the surface layer material qualitatively change from the solid state to a mixed state composed of gases, liquids and solid. The frictional modality of the braking changes accordingly from dry friction to lubrication with gases and liquids. The sudden lubrication makes the friction coefficient fall suddenly and induces the FC phenomena.

Originality/value

An abnormal tribological phenomena called “Frictional catastrophe (FC)” was found in this paper. The investigations about the behaviors and mechanisms of the FC are considered helpful for improving the braking safety of mine hoisters and other machines.

Details

Industrial Lubrication and Tribology, vol. 65 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 4 September 2017

Wang Chengmin, Yang Xuefeng, Cai Xiguang, Ma Tao, Li Yunxi and Song Peilong

This paper aims to thrash out friction and wear properties of automobile brake lining reinforced by lignin fiber and glass fiber in braking process.

311

Abstract

Purpose

This paper aims to thrash out friction and wear properties of automobile brake lining reinforced by lignin fiber and glass fiber in braking process.

Design/methodology/approach

ABAQUS finite element software was used to analyze thermo-mechanical coupled field of friction materials. XD-MSM constant speed friction testing machine was used to test friction and wear properties of friction material. Worn surface morphology and mechanism of friction materials were observed by using scanning electron microscope.

Findings

The results show that when the temperature was below 350°C, worn mechanism of MFBL was mainly fatigue wear and abrasive wear, and worn mechanism of GFBL was mainly fatigue wear because MFBL contained lignin fiber. Therefore, it exhibits better mechanical properties and friction and wear properties than those of GFBL.

Originality/value

Lignin fiber can improve mechanical properties and friction and wear properties of the automobile brake lining.

Details

Industrial Lubrication and Tribology, vol. 69 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 2 September 2014

Yanzhong Wang and Bin Wei

The purpose of this study is to investigate wet multi-disc brake temperature field and optimal oil supply under continuous braking condition. The oil supply of wet multi-disc brake

Abstract

Purpose

The purpose of this study is to investigate wet multi-disc brake temperature field and optimal oil supply under continuous braking condition. The oil supply of wet multi-disc brake has a direct impact on the drivability and fuel economy for tracked vehicles. Too small flow will result in the higher temperature and failure of brake while excessive one will lead to slow engagement increasing disengaged torque and the transmission efficiency could decline notably. The optimal oil supply and brake temperature field were obtained in this research.

Design/methodology/approach

This article investigated on the heat dissipation capability and optimal oil supply of the brake by the means of CFX model. The working condition was continuous braking and the lubricating and cooling factors were included in the model.

Findings

That the complex trends with increased oil flow is inconsistent with the traditional formula in which the effects of grooves were neglected. The fitting curve of optimal oil supply can predict various needed oil flow in various rotating speed and it provides a theoretical guidance for oil supply design.

Originality/value

Traditional empirical formula of heat transfer coefficient and Reynolds equation solved by different methods could be difficult to deal with the complex boundary conditions of wet multi-disc brake. CFX model can solve the problem of complex boundary condition. The optimal oil supply curve can provide a theoretical guidance for oil supply design.

Details

Industrial Lubrication and Tribology, vol. 66 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 19 April 2023

Meixian Zhang, Hanbo Shi, Siyuan Ding and Lei Ma

The purpose of this paper is to study the influence of braking speed at –20 °C on the wear property of high-speed railway braking materials and the temperature also stress…

Abstract

Purpose

The purpose of this paper is to study the influence of braking speed at –20 °C on the wear property of high-speed railway braking materials and the temperature also stress analyses of brake disc friction surface.

Design/methodology/approach

Friction brake tester was used to simulate the wear test of high-speed railway braking materials at diverse braking speeds (2,100, 2,400, 2,700 and 3,000 rad/min) at –20 °C and the stress and temperature analyses of brake disc friction surface were carried out by COMSOL.

Findings

Compared with 20°C, there is initial stress of brake disc friction surface before brake starting; also, the maximum wear depth is larger at –20°C. Besides, at –20 °C, with the rising of braking speed, the graphite particles on the friction surface of brake pad significantly reduce. And scratches and cracks are formed on brake pad friction surface. Besides, the abrasive wear, adhesive wear and thermal cracks of brake disc friction surface are aggravated. Moreover, the maximal worn depth also increase. Meanwhile, the highest temperature and the maximum thermal stress of brake disc friction surface both raise. Furthermore, the temperature and thermal stress gradients at radial direction of brake disc friction surface aggrandize, which makes the thermal cracks on brake disc friction surface further exacerbated.

Research limitations/implications

In this paper, the wear property of the high-speed railway braking materials is studied by combining experiment and simulation. However, due to the low-speed traveling of high-speed railway was mainly studied in this paper, there may be no comprehensive simulation of the real running condition of high-speed railway. At the same time, the working condition of low-temperature environment cannot be completely simulated and controlled.

Practical implications

The research results of this paper provide a basic instruction for other researchers and also provide an important reference for relevant personnel to choose the braking speed of high-speed railway at –20 °C.

Social implications

The research of this paper provides a brick for the study of high-speed railway braking materials and also provides some references for the safe service of trains in low-temperature environment.

Originality/value

This paper studied the wear property and carried out the simulation analysis of braking materials at –20 °C at diverse braking speed. The research findings provide an important reference for the selection of braking speed of high-speed railway at –20 °C.

Details

Industrial Lubrication and Tribology, vol. 75 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 31 August 2022

İlker Sugözü, Cengiz Öner, İbrahim Mutlu and Banu Sugözü

The purpose of this study was to investigate the use of boric acid as a friction modifier material in brake friction composites and to determine the effect of heat treatment…

180

Abstract

Purpose

The purpose of this study was to investigate the use of boric acid as a friction modifier material in brake friction composites and to determine the effect of heat treatment applied during production on braking performance.

Design/methodology/approach

The addition of five different amounts of boric acid was balanced with cashew, which is in the friction modifier material group. The samples were produced in the following order: dry mixing, preforming and hot-pressing. The effect of the heat treatment that can be applied after the hot-pressing process on the braking performance was investigated. The tribological and physical properties of the samples were determined using tests performed according to appropriate standards. The microstructures of the friction surfaces were investigated using scanning electron microscopy.

Findings

It was observed that the tribological properties of brake friction composites containing 20% by weight of boric acid were improved. It has also been observed that the heat treatment applied after hot pressing increased the friction coefficient of the samples by 7% on average and decreased the specific wear ratio of the samples. When the surface morphologies of the samples are examined, it is seen that the friction layers of the heat-treated samples are wider, and the microvoids and cracks are reduced.

Originality/value

This study showed that boric acid can be used as a friction modifier in brake friction composites. It also revealed the tribological and physical contribution of the applied heat treatment to the composite. Thus, it guides brake friction composite manufacturers in the industry and researchers working in this field.

Details

Industrial Lubrication and Tribology, vol. 74 no. 10
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 22 September 2022

Justin Antonyraj I., Vijay R., Sathyamoorthy G. and Lenin Singaravelu D.

This paper aims to discuss the influence of graphite with varying purity on the tribological performance of brake pads.

Abstract

Purpose

This paper aims to discuss the influence of graphite with varying purity on the tribological performance of brake pads.

Design/methodology/approach

Three distinct brake pads were created within the scope of this experiment by varying the graphite purity without affecting the other components. The brake pads were made using a traditional manufacturing procedure, and industry standards were used to test the chemical, physical and mechanical properties of the newly produced brake pad. A full-scale inertia brake dynamometer was used to determine the material’s tribological characteristics. The worn surfaces of the brake pads were examined using a scanning electron microscope.

Findings

The test results indicate that brake pads containing 99% pure graphite (artificial grade) displayed good physical, chemical and mechanical features, such as consistent friction and a reduced rate of wear because of the lower impurity level, which eliminates frictional undulations.

Originality/value

This paper discusses the influence of graphite purity on the tribological performance of brake pads by modifying tribofilms and reducing friction undulations.

Details

Industrial Lubrication and Tribology, vol. 75 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

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