carBrake padsIt refers to the friction material fixed on the brake drum or brake disc that rotates with the wheel. The friction lining and the friction lining bear external pressure and generate friction to achieve the purpose of vehicle deceleration.
The friction block is clampedpistonPushing the friction material squeezed on the brake disc, due to friction, the friction block will gradually be worn out, generally speaking, the lower the costbrakeThe faster the sheet wears. The friction block is divided into two parts: the friction material and the bottom plate. The friction material part can still be used after wear. After the friction material is used up, the bottom plate and the brake disc will directly contact, which will eventually lose the braking effect and damage the brake disc. The repair cost of brake discs is very expensive. Generally, the basic requirements for brake pads mainly include wear resistance, high friction coefficient, and excellent heat insulation performance.
According to the different braking methods, the brake pads can be divided into two types: drum brake pads and disc brake pads. According to different materials, the brake pads can generally be divided into asbestos type, semi-metal type, NAO type (that is, no Asbestos organic matter type) brake pads and other three types.
With the rapid development of modern technology, like otherBraking SystemThe brake pad itself has also been continuously developed and changed in recent years.
In the traditional manufacturing process, the friction material used on the brake pad is a mixture of various adhesives or additives, and fibers are added to it to increase its strength and play a role of reinforcement. Brake pad manufacturers tend to be tight-lipped when it comes to announcements on materials used, especially new formulations. Of course, some ingredients such as mica, silica, and rubber fragments are public. The final effect of brake pad braking, wear resistance, temperature resistance and other properties will depend on the relative proportions of different components. Here is a brief talk about several different materials of brake pads.
Asbestos type brake pads
Asbestos has been used as a reinforcement material for brake pads from the very beginning. Because asbestos fiber has high strength and high temperature resistance, it can meet the requirements of brake pads and brake pads.Clutch discAnd liner requirements. This fiber has strong tensile strength, can even match with high-grade steel, and can withstand high temperatures of 316°C. More importantly, asbestos is relatively cheap, it is extracted from amphibole ore, and this ore has been found in large numbers in many countries.
Asbestos accounts for 40-60% of the composition of asbestos-type brake pads, but it is now found that most asbestos has potential hazards. Asbestos has been confirmed by the medical community to be a carcinogen, and its needle-like fibers can easily enter the lungs. Staying, causing irritation, can eventually lead to the occurrence of lung cancer, but the incubation period of this disease can be as long as 15-30 years, so people often do not realize the harm 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 workers, but 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 Occupational Safety and Health Association (OSHA), every time a routine friction test is performed, millions of asbestos fibers will be emitted into the air from the brake pads, and this fiber is much smaller than that of humans. Her hair is invisible to the naked eye, so a single breath may suck thousands of asbestos fibers without people noticing it. Similarly, if an air tube is used to blow away the brake dust in the brake drum or brake parts, countless asbestos fibers can also be blown into the air. These dust will not only affect the health of the working technicians, but also affect any Other people present caused health damage. Even some extremely simple operations such as: hitting the brake drum with a hammer to loosen it, allowing the internal brake dust to come out, can also produce a large amount of asbestos fiber floating into the air. What is even more worrying is that once the fibers float in the air, they will last for several hours, and then they will stick to clothes, desktops, tools and other surfaces you can think of. Whenever they encounter agitation (such as cleaning, walking, air flow when using pneumatic tools), they will re-float into the air. Normally, once this material enters the work environment, it will stay there for months or even years, causing potential health effects on the people working there and even customers.
The American Occupational Safety and Health Association (OSHA) also pointed out: People’s working environment has asbestos fiber content not exceeding 0.2 per square meter to be safe, and at the same time, asbestos dust generated in daily brake maintenance work should be reduced as much as possible. Try to avoid work that may cause the release of dust (such as knocking on the brake pads, etc.).
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