ZX MOTOR News

Asbestos has been used as a reinforcing material for brake pads from the beginning. Because of its high strength and high temperature resistance, asbestos fiber can meet the requirements of brake pads, clutch discs and liners. This kind of fiber has strong tensile strength, even can match with high-grade steel, and can withstand high temperature of 316 ℃. What's more, asbestos is relatively cheap. It is extracted from amphibole ore, which has been found in large quantities in many countries.

Asbestos accounts for 40-60% of the components of asbestos brake pads. However, it has been found that most asbestos has potential hazards. Asbestos has been confirmed as a carcinogen by the medical community. Its needle like fibers are easy to enter the lungs and stay, causing irritation, and eventually lead to lung cancer. However, the incubation period of this disease can be as long as 15-30 years, so people often fail to recognize it Hazards caused by asbestos.

As long as the asbestos fiber is fixed by the friction material itself, it will not cause harm to the health of the staff. However, when the asbestos fiber is discharged along with the brake friction to form brake dust, it may become a series of root causes affecting health.

According to the test made by the American Occupational Safety and Health Association (OSHA), every time a routine friction test is carried out, millions of asbestos fibers will be produced in the brake pad, which are emitted into the air. Moreover, this kind of fiber is far smaller than the human hair and can not be observed by the naked eye. Therefore, thousands of asbestos fibers may be inhaled in one breath without people's awareness. Similarly, if the brake dust in the brake drum or brake parts is blown away by air pipe, countless asbestos fibers can also be blown into the air. The dust will not only affect the health of the technician, but also cause health damage to any other personnel present. Even some extremely simple operations, such as striking the brake drum with a hammer to make it loose and let the internal brake dust come out, can also produce a large amount of asbestos fiber floating into the air. What's even more worrying: once fibers float in the air for hours, they stick to clothes, tabletops, tools, whatever you can think of. Any time they encounter turbulence (e.g. cleaning, walking, air flow when using pneumatic tools), they will float back into the air again. Usually, once the material enters the work environment, it will stay there for months or even years, with potential health effects on the people working there and even customers.

The American Occupational Safety and Health Association (OSHA) also pointed out that the asbestos fiber content in people's working environment should not exceed 0.2 per square meter. At the same time, the asbestos dust generated in daily brake maintenance should be reduced as much as possible, and the work that may release dust (such as knocking the brake pads, etc.) should be avoided as far as possible.

However, in addition to health hazards, there is another important problem in asbestos brake pads. Because asbestos is adiabatic, its thermal conductivity is particularly poor. Usually, repeated use of the brake will make heat accumulate in the brake pad. After the brake pad becomes hot, its braking performance will change. To produce the same friction and braking force, it will need more times to step on the brake. This phenomenon is called "brake shrinkage". If the brake pad reaches a certain heat, it will lead to braking Movement failure.

When vehicle manufacturers and brake material suppliers decided to develop new and safer alternatives to asbestos, new friction materials came into being almost at the same time. These are the "semi metallic" and non asbestos organic (NAO) brake pads.