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What is the material of heavy commercial vehicle brake discs made of?

Views:0     Author:Site Editor     Publish Time: 2021-11-04      Origin:Site

Brake discs are an important part of the braking system. If the braking system is to always slow down the vehicle safely and comfortably - bringing it to a complete stop if necessary - the brake discs must combine with the brake pads to generate braking torque (braking force). This torque is transferred to the wheel hub and from there to the rim. During braking, the kinetic energy of the vehicle is converted into heat due to the friction between the brake lining and the brake disc, which enables a reduction in speed to be achieved.


brake discs

History of car brake discs

High carbon discs

Gray cast iron

Ceramic materials


History of car brake discs

At the end of the 19th century, there was a need to develop braking systems for newly invented automobiles. Since that time, devices were developed that used several components, among them brake discs. After the outbreak of World War II in 1938, the development of braking system technology was given a major boost by the needs of the aviation industry. Historically, the first material used to manufacture brake discs was gray cast iron that met its intended requirements, such as good thermal conductivity, good corrosion strength, low noise, low weight, long life, stable friction, low wear rate and good cost performance. Therefore, for more than a hundred years, many materials have been developed for this purpose, among which the most used is still  cheap and easy to produce gray cast iron. But in recent years there is also more than one material used for the manufacture of automotive brake discs such as reinforced carbon-carbon or ceramic matrix composites. The brake disc material must meet strict requirements. It must be able to withstand the mechanical stresses applied during braking due to pressure and tension, the centrifugal force at high wheel speeds and thermal loads.


High carbon discs

High carbon discs have optimal thermal conductivity, ensuring more consistent braking performance by keeping discs running cooler.

High carbon discs offer higher resistance to deformation to maintain vehicle performance

High carbon discs offer better stability and improved resistance to deformation and thermal cracking due to improved thermal properties

High-carbon discs also offer quieter, chatter-free performance, resulting in an improved driving experience.


Gray cast iron

Most brake discs are made of special gray cast iron (pearlized gray cast iron). Alloys containing chromium and molybdenum increase the wear resistance and improve the thermal cracking characteristics of the material. In addition, the high carbon content increases the heat absorption rate. This is made possible by the high amount of graphite in the microstructure, which results in lower temperatures in the friction region and then extends the lifetime of the component. Gray iron has good thermal conductivity due to the graphite phase, which is an excellent thermal conductor.


Ceramic materials

Ceramic materials (carbon fiber ceramic or carbon ceramic) are also increasingly used in the manufacture of brake discs. Firstly, ceramic materials have high dimensional stability in all temperature ranges and are suitable for use in the high temperature environments that are instantaneously generated during automotive braking. Second, ceramic materials have low dead weight, which is certainly a good way to reduce body weight. Thirdly, good brake response, which can react to possible danger ahead in a very short time.

Fourth, the ceramic material has an extremely long service life, which means you don't need to replace it as often. Fifth, ceramic materials have excellent decay characteristics, and you can tell when they need to be replaced.

Their disadvantages include poor thermal conductivity (which requires the use of special materials for the brake linings) and very high prices. The latter undoubtedly explains why ceramic brake discs are currently used only as special equipment in high-powered premium cars.


Conclusion

Brake discs are subjected to very high mechanical and thermal loads. In addition to these factors, there are also environmental factors such as water spray, road dirt and paving materials. As a result, they are subject to natural wear and tear. The condition of the brake discs should be checked at every vehicle inspection. If the wear limit is reached, they must be replaced to ensure the reliable function of the braking system. That's why we have a strict selection of materials used in the manufacture of automotive brakes and guarantee good after-sales service, contact us!


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