scholarly journals A Study of the Effect of Brake Pad Scorching on Tribology and Airborne Particle Emissions

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 488 ◽  
Author(s):  
Jens Wahlström ◽  
Mara Leonardi ◽  
Minghui Tu ◽  
Yezhe Lyu ◽  
Guido Perricone ◽  
...  

Non-exhaust wear emissions from disc brakes affect the air quality in cities throughout the world. These emissions come from the wear of the contact surfaces of both the pads and disc. The tribological and emissions performance of disc brakes strongly depend on the contact surface characteristics of the pads and discs. The surfaces of conventional pads are scorched by heating it to several hundred degrees to make the resin carbonize down to a few millimetres deep into the pad. This is done to have a shorter run-in period for new pads. It is not known how scorching will affect the amount of airborne particle emissions. Therefore, the aim of the present study is to investigate how pad scorching influence the airborne particle emissions. This is done by comparing the pin-on-disc tribometer and inertia dyno bench emission results from a Cu-free friction material run against a grey cast iron disc. Three types of modified friction material surfaces have been tested: scorched, extra-scorched and rectified. The results show that the level of scorching strongly affects the airborne particle emissions in the initial phase of the tests. Even if the scorched layer is removed (rectified) before testing, it seems like it still has a measurable influence on the airborne particle emissions. The results from the tribometer tests are qualitatively in line with the inertia dyno bench test for about the first forty brake events; thereafter, the airborne particle emissions are higher for the scorched pads. It can be concluded that it seems that the level of scorching has an adverse influence on both the tribological performance and level of particle emissions.

2020 ◽  
Vol 21 (6) ◽  
pp. 613
Author(s):  
Amira Sellami ◽  
Nesrine Hentati ◽  
Mohamed Kchaou ◽  
Mohammad Asaduzzaman Chowdhury ◽  
Riadh Elleuch

Friction materials are composed of numerous ingredients which differ from nature and particles size. Each ingredient has its own impact on the mechanical and tribological behavior of the material. Brass ingredients have a great impact on the thermal gradient dissipation in the sliding contact between disc and brake pad material. In this research, the influence of different sizes and forms of brass ingredient was studied on the friction material behavior. The physical (density), mechanical (yield strength, young module) and thermal (thermal conductivity and specific heat) properties of the considered composites were characterized. Results proves that only physical and mechanical properties are sensitive to the changes in size and form of brass particles. The tribological behavior of the brake friction materials was also assessed using a pin-on-disc tribometer. The results show that bigger brass particles and their elongated shape allows it to be well embedded on the pad surface during braking application, and thus decreased wear rate . In contrast, the smaller particle decrease the friction stability and it rounded shape increase wear of the material since it tearing from the surface by abrasive wear.


This paper aims to present comparative study of friction and wear characteristics of non-asbestos rubber resin bonded metallic based brake pad material. Friction material was compression moulded and machined to a sample size. Their physical and mechanical properties were studied. Experiments were conducted using Pin-on-disc test set-up against EN31 disc. Coefficient of friction and wear was measured for metallic based brake materials at varying conditions of temperature, sliding velocity, pressure and sliding distance. When brake pads are in contact with brake disc, heat is generated hence thermal behaviour of metallic based brake material and its impact on friction and wear were studied. Experiments, based on Taguchi’s analysis technique, using L9 orthogonal array were performed. On the basis of experimental results and S/N ratio analyses, ranking of the parameters have been done. It was found that temperature (95.37 %) and sliding velocity (2.99 %) are most affecting parameters in friction, However temperature (82.96 %) and pressure (6.80) in wear. The elemental composition of metallic based brake material was measured by EDS technique. SEM micrographs of brake pad samples were tested at different magnifications. Further detailed studies are suggested to evaluate wear rate, stopping distance under simulative test conditions alternate to asbestos based brake pad material.


2020 ◽  
Vol 27 (1) ◽  
pp. 374-396
Author(s):  
Andrzej Borawski

AbstractBrakes are one of the most important components of vehicle. The brake system must be reliable and display unchanging action throughout its use, as it guards the health and life of many people. Properly matched friction pair, a disc and brake pad (in disc brakes), have a great impact on these factors. In most cases, the disc is made of grey cast iron. The brake pads are far more complex components. New technologies make it possible to develop materials with various compositions and different proportions, and connect them permanently in fully controllable processes. This elaboration shows that all these factors have a greater or lesser impact on the coefficient of friction, resistance to friction wear and high temperature, and brake pad’s operating life. This review collects the most important, the most interesting, and the most unconventional materials used in production of brake pads, and characterizes their impact on the tribological properties of pads.


Wear ◽  
2017 ◽  
Vol 384-385 ◽  
pp. 124-130 ◽  
Author(s):  
Jens Wahlström ◽  
Yezhe Lyu ◽  
Vlastimil Matjeka ◽  
Anders Söderberg

2012 ◽  
Vol 531-532 ◽  
pp. 8-12
Author(s):  
M.A. Sai Balaji ◽  
K. Kalaichelvan

Organic fibres (Kevlar/ Arbocel / Acrylic) have good thermal stability, higher surface area and bulk density. The optimization of organic fibres percentage for thermal behaviour is considered using TGA. The temperature raise during brake application will be between 150-4000 C and this temperature zone is very critical to determine the fade characteristics during friction testing. Hence, three different friction composites are developed with the same formulation varying only the Kevlar, Arbocel and Acrylic fibres which are compensated by the inert filler namely the barites and are designated as NA01, NA02 and NA03 respectively. After the fabrication, the TGA test reveals that the composite NA03 has minimum weight loss. The friction coefficient test rig is then used to test the friction material as per SAE J661a standards. The results prove that the brake pad with minimum weight loss during TGA has higher friction stability. Thus, we can correlate the thermal stability with the stability of friction.


Author(s):  
Yan Yin ◽  
Jiusheng Bao ◽  
Jinge Liu ◽  
Chaoxun Guo ◽  
Tonggang Liu ◽  
...  

Disc brakes have been applied in various automobiles widely and their braking performance has vitally important effects on the safe operation of automobiles. Although numerous researches have been conducted to find out the influential law and mechanism of working condition parameters like braking pressure, initial braking speed, and interface temperature on braking performance of disc brakes, the influence of magnetic field is seldom taken into consideration. In this paper, based on the novel automotive frictional-magnetic compound disc brake, the influential law of magnetic field on braking performance was investigated deeply. First, braking simulation tests of disc brakes were carried out, and then dynamic variation laws and mechanisms of braking torque and interface temperature were discussed. Furthermore, some parameters including average braking torque, trend coefficient and fluctuation coefficient of braking torque, average temperature, maximum temperature rise, and the time corresponding to the maximum temperature rise were extracted to characterize the braking performance of disc brakes. Finally, the influential law and mechanism of excitation voltage on braking performance were analyzed through braking simulation tests and surface topography analysis of friction material. It is concluded that the performance of frictional-magnetic compound disc brake is prior to common brake. Magnetic field is greatly beneficial for improving the braking performance of frictional-magnetic compound disc brake.


Wear ◽  
2010 ◽  
Vol 268 (5-6) ◽  
pp. 763-769 ◽  
Author(s):  
Jens Wahlström ◽  
Anders Söderberg ◽  
Lars Olander ◽  
Anders Jansson ◽  
Ulf Olofsson

2013 ◽  
Vol 471 ◽  
pp. 81-85 ◽  
Author(s):  
Ahmad Razimi Mat Lazim ◽  
Abd Rahim Abu Bakar ◽  
Mohd Kameil Abdul Hamid ◽  
Izzat Mohd Asri

Researchers in recent years begin to explore on tribological behavior of automotive brake squeal phenomena which covers the morphology, chemical composition, friction and wear, phase composition and third body or friction film distribution. However less effort has been made to study the tribological on the influence of small particles on brake squeal. During braking condition, both rotor and pads are exposed to road environmental particle which may affect pads surface condition. In order to assess the influence of this particle on brake squeal a series of squeal tests were performed. Silica sand grit particles with a size range between 400 to 200 μm which most available on the road surface were used in this experiment. Brake pad and disc surface characteristics were analyzed before and after squealing condition using Scanning Electron Microscope (SEM) and Energy dispersive X-ray analysis (EDX). The result shows that the silica sand particles had influence the squeal and surface behavior of the brake pad.


Author(s):  
CH Achebe ◽  
JL Chukwuneke ◽  
FA Anene ◽  
CM Ewulonu

The development of automobile brake pad using locally sourced palm kernel fiber was carried out. Asbestos, a carcinogenic material, has been used for decades as a friction material. This development has thus prompted a couple of research efforts geared towards its replacement for brake pad manufacture. Palm kernel fiber was used as an alternative filler material in conjunction with various quantities of epoxy resin as the matrix. Three sets of compositions were made, and the resulting specimens subjected to physical and mechanical tests using standard materials, procedures, and equipment. The essence is to determine their suitability and hence possible performance in service. The result showed that sample C with 40% palm kernel fiber content having hardness, compressive strength, abrasion resistance, specific gravity, water absorption, and oil absorption of 178 MPa, 96.2 MPa, 1.67 mg/m, 1.8 g/cm3, 1.86%, and 0.89%, respectively, had an optimum performance rating. It was equally ascertained that increase in the filler content had the effect of increase in hardness, wear resistance, and specific gravity of the composite brake pad, while water and oil absorption got decreased when compared with results obtained by other researchers using conventional brake pads made of other friction materials including asbestos. This is an indicator that palm kernel fiber is a possible and effective retrofit for asbestos as a filler material in automotive brake pad manufacture.


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