THE INFLUENCE OF THE SURFACE LAYER STRUCTURE IN DISC BRAKE PADS ON THEIR TRIBOLOGICAL PROPERTIES

Tribologia ◽  
2016 ◽  
Vol 267 (3) ◽  
pp. 71-85
Author(s):  
Andrzej GAJEK ◽  
Wojciech SZCZYPIŃSKI-SALA
Keyword(s):  
Friction Surface ◽  
Chemical Elements ◽  
Layer Structure ◽  
Friction Material ◽  
Compact Structure ◽  
Friction Layer ◽  
Brake Pads ◽  
Disc Brakes ◽  
The Coefficient Of Friction ◽  
Point Line

The article presents the results of the stand tribological investigation and microscopic observations of brake pad materials for automotive disc brakes. The reasons for the scatter of the friction coefficient value are analysed. The results of the brake pads’ friction surface topography observations and chemical constitution are presented. The investigations were carried out with scanning electron microscopy SEM and energy dispersive X-ray spectroscopy EDS. The point, line, and surface analysis of friction layer were done. The average contents of the chemical elements on the friction surface are presented. The heterogeneous nature of the structure on the friction layer was observed. The analysis has shown that brake pads with a compact structure of friction layer and large quantity components (10 components with more than 1% content each) had a smaller scatter of the coefficient of friction value in relation to the materials with a loose structure and less quantity components. The next part of the article presents the structure and geometric parameter products of the wear of the friction material. The problem concerning the quantity limitation of the wear particles entering the environment as dust was discussed.

scholarly journals Impact of Operating Time on Selected Tribological Properties of the Friction Material in the Brake Pads of Passenger Cars

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 884
Author(s):  
Andrzej Borawski
Keyword(s):  
Tribological Properties ◽  
Operating Time ◽  
Friction Material ◽  
Operating Conditions ◽  
Direct Impact ◽  
Passenger Cars ◽  
Wear Factor ◽  
Brake Pads ◽  
Road Users ◽  
The Coefficient Of Friction

Braking systems have a direct impact on the safety of road users. That is why it is crucial that the performance of brakes be dependable and faultless. Unfortunately, the operating conditions of brakes during their operating time are affected by many variables, which results in changes in their tribological properties. This article presents an attempt to develop a methodology for studying how the operating time affects the value of the coefficient of friction and the abrasive wear factor. The Taguchi method of process optimization was used to plan the experiment, which was based on tests using the ball-cratering method. The results clearly show that the degree of wear affects the properties of the friction material used in the production process of brakes.

scholarly journals A Factorial Design to Numerically Study the Effects of Brake Pad Properties on Friction and Wear Emissions

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Jens Wahlström
Keyword(s):  
Factorial Design ◽  
Coefficient Of Friction ◽  
Friction And Wear ◽  
Friction Material ◽  
Particulate Emissions ◽  
Third Body ◽  
Wear Process ◽  
Disc Brakes ◽  
The Coefficient Of Friction ◽  
Contact Situation

Airborne particulate emissions originating from the wear of pads and rotors of disc brakes contribute up to 50% of the total road emissions in Europe. The wear process that takes place on a mesoscopic length scale in the contact interfaces between the pads and rotors can be explained by the creation and destruction of contact plateaus. Due to this complex contact situation, it is hard to predict how changes in the wear and material parameters of the pad friction material will affect the friction and wear emissions. This paper reports on an investigation of the effect of different parameters of the pad friction material on the coefficient of friction and wear emissions. A full factorial design is developed using a simplified version of a previously developed cellular automaton approach to investigate the effect of four factors on the coefficient of friction and wear emission. The simulated result indicates that a stable third body, a high specific wear, and a relatively high amount of metal fibres yield a high and stable mean coefficient of friction, while a stable third body, a low specific wear, a stable resin, and a relatively high amount of metal fibres give low wear emissions.

Study of the frictional properties of brake pads with different relief of oil ducts

2015 ◽  
Vol 5 (1) ◽  
pp. 215-222
Author(s):  
Поляков ◽  
Nikolay Polyakov
Keyword(s):  
Friction Surface ◽  
Friction Material ◽  
Supply System ◽  
Brake Pads ◽  
Frictional Properties ◽  
Braking Torque ◽  
Order Of Magnitude ◽  
Scale Experiment ◽  
Selection Of ◽  
Tractor Plant

Some technological operations – stump extraction, preparation of forest roads are made by machines based on powerful caterpillar tractors. One of the problematic units of caterpillar tractors is band brakes of "dry" friction. Typically, friction tape must be changed after two ТО-3. Belt shoe brakes, working in oil, have higher durability (at least one order of magnitude). Apart from the choice of a special friction material for such a brake oil supply system must be ensured and special oil ducts on the working surfaces of the pads. In the literature several fundamental configurations of ducts are known. We, together with specialists from Cheboksary Industrial Tractor Plant have selected cruciform shape of cutting ducts. Due to a variety of factors and difficulties passing on the cutting-friction contact of phenomena analytical method for the selection of the geometry of ducts is difficult. We used full-scale experiment with the previously selected friction asbestos polymer material no. 410-120. Tests were conducted on a combined stand. To simplify this type of test we used not the whole belt of the four pads, but only one pad. To do this, stand design was modified; strain-gage chain was changed to record braking torque. The tests were carried out under braking stops. Different geometries of oil ducts on the different modes of operation were explored. The following parameters were varied: the density of cutting; the width of the ducts; depth of the ducts; angle to the axis of the ducts. Frictional properties and the temperature at the friction surface were evaluated. The best performances of ducts cutting were chosen after tests. mm; mm; mm ; . The results of the work are introduced in production.

scholarly journals Functionalization of alumina particles to improve the performance of eco-friendly brake-pads

Friction ◽  
2021 ◽  
Author(s):  
Vanvirsinh Chauhan ◽  
Jayashree Bijwe ◽  
Ashish Darpe
Keyword(s):  
Friction And Wear ◽  
Friction Material ◽  
Abrasive Particles ◽  
Inorganic Particles ◽  
X Ray ◽  
Brake Pads ◽  
Matrix Adhesion ◽  
Alumina Particles ◽  
The Coefficient Of Friction ◽  
Resin Binder

AbstractAbrasives, such as oxides of alumina (Al), silica (Si), zirconia (Zr), chromium (Cr) etc., are added to raise the friction level and also to remove the glaze on the disc so that surface will be rejuvenated continuously during braking and will contribute to maintain the desired friction level. However, these inorganic particles have less adhesion with the resin/binder and hence are easily dug out during wearing process contributing to higher wear. If efforts are made to enhance the filler-matrix adhesion, not only the wear of friction material (FM) should reduce, the particles may stay for a longer time on the tribo-surface of the pads to contribute fully towards controlling the coefficient of friction (μ). In the present study, alumina particles were selected for siloxane treatment to improve the filler-matrix adhesion. Two types of eco-friendly (free from asbestos and Cu) brake-pads were developed using alumina as a theme ingredient (treated and untreated) keeping all the parent formulation identical. An additional type of brake-pads without alumina particles was also developed to observe the effect of abrasive particles on the tribo-performance. The performance properties (physical, mechanical, and tribological) of brake-pads were compared when evaluated in identical conditions. The tribo-testing was done on full-scale brake inertia dynamometer following the procedure in Japanese automobile standard (JASO C 406). It was observed that siloxane treatment affected both friction and wear of brake-pads in a beneficial way. Wear resistance got increased 35% for siloxane treated pads. Worn surfaces were analysed using scanning electron microscopy (SEM) and energy dispersive X-ray (EDAX) technique.

scholarly journals Conventional and unconventional materials used in the production of brake pads – review

2020 ◽  
Vol 27 (1) ◽  
pp. 374-396
Author(s):  
Andrzej Borawski
Keyword(s):  
New Technologies ◽  
Friction Pair ◽  
Brake Pad ◽  
Operating Life ◽  
Friction Resistance ◽  
Brake Pads ◽  
Disc Brakes ◽  
The Coefficient Of Friction ◽  
Grey Cast ◽  
Materials Used

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.

Dry Sliding Wear Studies of Cu-Based Powder Metallurgy Brake Materials

2012 ◽  
Author(s):  
Glenn K. Gyimah ◽  
Dong Chen ◽  
Ping Huang
Keyword(s):  
Sliding Wear ◽  
Wear Behavior ◽  
Friction Material ◽  
Dry Sliding Wear ◽  
Temperature Sensitive ◽  
Brake Pads ◽  
Different Temperatures ◽  
The Coefficient Of Friction ◽  
Materials Used ◽  
Mechanical And Tribological Characteristics

A novel friction material based on Cu-based powder with several additional elements, such as Al, SiO2, Fe, graphite, Sn, Mn and MoS2, has been developed by PM techniques in order to study the wear to improve mechanical and tribological characteristics of train brake pads. The materials used were sintered at three different temperatures (850°C, 900°C and 950°C). A high pressure pad-on-disc braking tester was developed to test the wear behavior of these materials without lubrication. Wear was measured by microscopic examination of the pad after the tribometer test. The tests showed that the coefficient of friction (COF), wear rate and wear number were improved immensely by high temperature sintering. This shows that the sintering temperature level plays an important role in the performance of the braking material. In addition, the tribological and the mechanical properties were found to be temperature sensitive.

Braking performance of a novel frictional-magnetic compound disc brake for automobiles

2018 ◽  
Vol 233 (10) ◽  
pp. 2443-2454 ◽  
Author(s):  
Yan Yin ◽  
Jiusheng Bao ◽  
Jinge Liu ◽  
Chaoxun Guo ◽  
Tonggang Liu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Temperature Rise ◽  
Friction Material ◽  
Maximum Temperature ◽  
Interface Temperature ◽  
Disc Brake ◽  
Braking Performance ◽  
Maximum Temperature Rise ◽  
Disc Brakes ◽  
Braking Torque

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.

Frictionally Excited Thermoelastic Instability in Automotive Drum Brakes

1999 ◽  
Vol 122 (4) ◽  
pp. 849-855 ◽  
Author(s):  
Kwangjin Lee
Keyword(s):  
Coefficient Of Friction ◽  
Material Properties ◽  
Critical Speed ◽  
Hot Spot ◽  
Frictional Heating ◽  
Friction Material ◽  
Thermoelastic Instability ◽  
Critical Speeds ◽  
Drum Brake ◽  
The Coefficient Of Friction

Thermoelastic instability in automotive drum brake systems is investigated using a finite layer model with one-sided frictional heating. With realistic material properties of automotive brakes, the stability behavior of the one-sided heating mode is similar to that of the antisymmetric mode of two-sided heating but the critical speed of the former is higher than that of the latter. The effects of the friction coefficient and brake material properties on the critical speeds are examined and the most influential properties are found to be the coefficient of friction and the thermal expansion coefficient of drum materials. Vehicle tests were performed to observe the critical speeds of the drum brake systems with aluminum drum materials. Direct comparisons are made between the calculation and measurement for the critical speed and hot spot spacing. Good agreement is achieved when the critical speeds are calculated using the temperature-dependent friction material properties and the reduced coefficient of friction to account for the effect of intermittent contact. [S0742-4787(00)01503-4]

Heat Dissipation and Temperature Distribution of Brake Liner Using Steady State Analysis

2012 ◽  
Vol 249-250 ◽  
pp. 712-717
Author(s):  
M.P. Natarajan ◽  
B. Rajmohan
Keyword(s):  
Heat Dissipation ◽  
Friction Material ◽  
Automotive Application ◽  
Element Analysis ◽  
Slowing Down ◽  
Drum Brake ◽  
The Coefficient Of Friction ◽  
Machine Elements ◽  
Braking Process ◽  
Good Agreement

Brakes are machine elements that absorb kinetic energy in the process of slowing down or stopping a moving part. Brake capacity depends upon the unit pressure between the braking surfaces, the coefficient of friction, and the ability of the brake to dissipate heat equivalent to the energy being absorbed. In braking system, drum brake is used mostly for automotive application. During the braking process, the forces and pressures in a drum brake are difficult to determine because of the manner in which the shoe contacts the drum. Finite Element analysis has been used to predict interface temperatures and heat flows and the results have been compared with experimental measurements made using fine thermocouples. Good agreement has been achieved, showing that the proportion of heat which flows into the friction material varies with time and temperature.

A retrofit for asbestos-based brake pad employing palm kernel fiber as the base filler material

2018 ◽  
Vol 233 (9) ◽  
pp. 1906-1913 ◽  
Author(s):  
CH Achebe ◽  
JL Chukwuneke ◽  
FA Anene ◽  
CM Ewulonu
Keyword(s):  
Specific Gravity ◽  
Palm Kernel ◽  
Friction Material ◽  
Mechanical Tests ◽  
Filler Material ◽  
Oil Absorption ◽  
Brake Pad ◽  
Brake Pads ◽  
The Matrix ◽  
Automotive Brake

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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