From the very beginning of asbestos has been used as a brake on the reinforcement, because asbestos fibers have high strength and high temperature characteristics, so to meet the brake and clutch disc and liner requirements. This fiber has strong tensile strength, or even to match with high-grade steel and can withstand high temperature 316 ¡æ. More importantly, asbestos is relatively cheap, which is extracted from the amphibole minerals, and such ores in many countries has been found in plenty.

    In the asbestos-type brake components ratio, asbestos accounts for 40 to 60%, but it has now found that most of the potential hazards of asbestos, asbestos medical profession has been proven to be carcinogenic, its needle-like fibers easily enter the lungs and remain, resulting in stimulation, ultimately leading to lung cancer, but this disease can lie dormant for up to 15 to 30 years, so people often do not recognize the harm caused by asbestos. As long as the asbestos fibers are fixed friction material itself will not cause harm to the health of staff, but when the asbestos fibers associated with the formation of the brake friction brake dust and emissions, it could become a source of impact on health.

    According to the U.S. Occupational Safety and Health Association (OSHA) to make the test routine once for each friction test, brake pads will have many millions of asbestos fibers into the atmosphere, and this fiber is much less than people hair, is the naked eye can not be observed, so the first breath may be inhaled asbestos fibers while thousands of people are unaware. Similarly, if the air pipe to the brake drum or brake parts in the brake dust blown away, numerous asbestos fibers can also be blown in the air, and these dust will not only affect the health technician, the same will be for any the presence of other persons to cause health damage. Even some very simple operations such as: brake drum with a hammer to knock loose, let out the internal brake dust, asbestos fibers can produce a large number of floats in the air.

    Even more worrying is this: Once the fibers float in air for several hours, then they will stick to the clothes, desktop, tools, everything you can think of the upper surface of the object. But any time a stirring encounter (such as cleaning, walking, using pneumatic tools generate air flow), they also will be re-floated into the air. Typically, once this material into the work environment, where it will stay as long as several months or even years, to where the staff and even customers to a potential health effects.

    U.S. Occupational Safety and Health Association (OSHA) also pointed out: people's work environments of the asbestos fiber content is not only more than 0.2 per square meter is safe, should also be routine brake maintenance work to minimize asbestos dust generated, Try to avoid the release of dust may cause the work (such as percussion brake pads, etc.).

    But in addition to endangering health factors, asbestos-type brake, there are still another important issue. As asbestos is adiabatic, the thermal conductivity is particularly poor, often repeated use of brakes will heat the film piled up in the brake, brake gets hot, it is necessary to change the braking performance to produce the same friction and braking force The brakes will need more frequency, a phenomenon known as "brake atrophy", if the heat reaches a certain brake pads, will result in brake failure. When the vehicle manufacturer and supplier of brake materials, decided to develop new and safer alternatives to asbestos, the new friction material is almost the same time came into being. This is the "semi-metal" type and a mixture of non-asbestos organic (NAO) brake pads.