Characterization and Comparison of Automobile Disc Brake Pads With Experimental Methods

Yıl 2018, Cilt: 30 Sayı: 3, 241 - 248, 30.09.2018

Polat Topuz

https://doi.org/10.7240/marufbd.403700

Cited By: 2

Öz

Brake linings are a key brake part because they are the component that contacts and applies pressure and friction to a vehicle’s brake rotors
– – those flat, shiny discs that you can sometimes see just behind the wheels of some vehicles. The pressure and friction applied to the
brake rotor is what slows and stops the wheel. Once the wheels stop turning, the vehicle stops moving, too. Though the role of brake linings
as braking parts is pretty simple, the brake linings themselves are anything but. If the car in motion cannot be stopped, there may be situations
that could lead to loss of life and property. For this reason, the most important system in terms of safety of life and property in road
vehicles such as automobiles is brake system. The most important part of the brake mechanism, which provides friction to the vehicle by
slowing down, is the brake lining. Brake linings must be at an acceptable cost proportional to a balanced coefficient of friction, low wear
rate, low noise level, lightness, environmental damage, good mechanical strength, corrosion resistance and performance. High temperature
during braking; fading phenomenon, premature wear, evaporation of brake fluid, bearing failures, thermal cracks and thermally induced
vibrations. Brake decline is a decrease in stopping power, especially in overload or repeated braking situations in high speed conditions.
Brake weakening is a phenomenon that occurs due to temperature in vehicles such as cars, trucks, motorcycles, planes and bicycles that
have a friction wheel. Proper driving style, brake equipment, material design and choice are factors that can significantly affect brake attenuation.
Brake pads were formerly manufactured using mainly asbestos as the friction material. That’s because brake pads are exposed to
[Açıklamalar]a lot of friction, which generates a lot of heat. Asbestos is a good material for absorbing and dissipating heat. So what was the
problem? When asbestos breaks down, it’s creates dust that’s dangerous to breathe – – and brake pads can create a lot of brake dust when
they’re slowing and stopping vehicles on the roads. Now, some brake pads and other brake parts are made from safer organic materials.
Organic brake pads, sometimes called nonasbestos organic brake pads, are made from natural materials liked glass and rubber, as well as
resins that can withstand high heat.All these features can be provided by composite brake linings containing many different components. These components are used as binders
(phenolic resins and rubber), as abrasives (steel, copper, brass, aramid, potassium titanate, rock wool, glass fiber), abrasive (zirconium
silicate, aluminum oxide, SiO2), fillers (barium sulphate, calcium carbonate, vermiculite), as a lubricant and as a friction modifier
(graphite, petroleum coke, molybdenum sulfur, antimony trioxide, zinc sulphide). For a composite brake lining, at least 10 of the above components are used in different quantities to produce pillars with
very different compositions and performances. Brake linings,
which are mainly produced by powder metallurgy, are obtained by
passing through mixing, molding and sintering steps. The materials
that make up the lining material are first mixed homogeneously for
a certain period of time. This mixture is then pressed into the mold
in the shape of a lining at a certain pressure, temperature and time.
After pressing, the mixture, which has been shaped like a mold, is
subjected to heat treatment in a sintering furnace at a certain temperature
and for a certain period of time. After the heat treatment,
the cooled sample of the lining becomes ready for the pre-use tests.
Composite brake linings are important safety elements used in friction
brake systems. Composite materials in brake linings; metallic,
semi-metallic, composite and carbon based. Some performance
characteristics of composites such as friction coefficient and wear
in brakes and clutches are the complex functions of matrix components
and compound components that the process cannot ignore.
In this study, the components of 3 disk brake linings, local and foreign,
belonging to automobiles used in our country; abrasion-friction
characteristics, mechanical and physical properties of these
materials were investigated by experimental studies and compared
with those of local, foreign and original (OEM) in terms of environment
and usage. In chemical analyzes, scanning electron microscopy
EDS (energy dispersive X-ray analysis) system and XRF
(X-ray fluorescence spectrometry) were used. TG (Thermo Gravimetric)
analyzes were performed to determine the mass losses in
the disc brake lining materials. In addition, DT (Differential Thermal)
analyzes were performed to detect the thermal changes. Wear
friction tests of linings were made according to JIS 4411 standard.
Apart from these, the hardness, density and internal shear strength
values of the linings are measured. The experimental data are compared
for the environment and use for foreign and local linings.

Anahtar Kelimeler

Automobile, disc brake, lining, characterization, environment and usage

Otomobil Disk Fren Balatalarının Deneysel Yöntemlerle Karakterizasyonu ve Karşılaştırılması

Öz

Bu çalışmada ülkemizde kullanılan otomobillere ait
yerli ve yabancı olmak üzere 3 adet fren disk balatasının bileşenleri;
aşınma-sürtünme karakteristikleri, mekanik ve fiziksel özellikleri açısından
deneysel çalışmalarla incelenmiş, yerli, yabancı ve orijinal (OEM) olanların
birbirleri ile çevre ve kullanım açısından karşılaştırılmaları yapılmıştır.
Kimyasal analizlerde, tarama elektron mikroskobu EDS sistemi ve XRF
kullanılmıştır. Balata malzemelerinin sıcaktaki kütle kayıplarını belirlemek
için TG (Termo Gravimetrik) analizleri yapılmıştır. Ayrıca ısısal
değişiklikleri tespit amacıyla DT (Diferansiyel Termal) analizleri
gerçekleştirilmiştir. Balataların aşınma sürtünme testleri JIS 4411 standardına
göre yapılmıştır. Bunların dışında balataların sertlik, yoğunluk, iç kesme
dayanım değerleri ölçülmüştür. Deneysel veriler yabancı ve yerli balatalar için
çevre ve kullanım açısından karşılaştırılmıştır.

Anahtar Kelimeler

Otomobil, disk fren, balata, karakterizasyon

Kaynakça

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• 3. P.J. Blau.: “Compositions, functions and testing of friction brake materials and their additives” Oak Ridge National Laboratory Technical Report ORNL/TM-2001/64, Oak Ridge, Tennessee, 2001
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