1, brake pads
, also known as brake pad brake pads. In the automotive brake systems, brake pads is the most critical safety components, the braking effect are all good or bad brakes play a decisive role in film, so that good brakes is the patron saint of people and cars. Brake pad typically made of steel, the adhesive insulating layer and the pad, wherein the insulating layer is composed of a material that does not transfer heat purpose of insulation. A friction pad material, a binder, is compressed on a friction brake disc or brake drum during braking so as to achieve the purpose of braking deceleration of the vehicle. Due to friction, the friction block will gradually be worn, in general, the lower the cost of brake pad wear faster. Friction materials after use timely replacement brake pads, or brake disc will be in direct contact with the plate, it will eventually lose braking effect and damage the brake disc.
Brake Pad
Brake Pad
[ 123] 2, composition and structure of
brake pad typically made of steel, the adhesive insulating layer and the pad, wherein the insulating layer is composed of a material that does not transfer heat purpose of insulation. A friction pad material, a binder, is compressed on a friction brake disc or brake drum during braking so as to achieve the purpose of braking deceleration of the vehicle. Due to friction, the friction block will gradually be worn, in general, the lower the cost of brake pad wear faster.
3, Category
Automotive brake pads from the divided type
– the brake pad for a disc brake
– a brake shoe for a drum brake
– for the truck to the film
from the formula technically divided: semi-metal, less metal, asbestos, ceramic,
4, Note
is tops brake drum brake shoes, but most people refer collectively called the brakes on brake pads and brake shoes, with “disc brakes” to indicate a particular disc brake coat brakes. Not the brakes.
brakes is that the brake system is the most critical safety features. Because the braking effect is good or bad brakes decisive role played piece, so that good brakes is the patron saint of people and cars. Friction materials after use timely replacement brake pads, or brake disc will be in direct contact with the plate, it will eventually lose braking effect and damage the brake disc.
5, brake pads type
different embodiment of the brake pad braking can be divided into: a brake drum brakes and disc brakes two kinds of brake, brake according to different materials asbestos sheet type generally divided into three, semi-metallic, NAO type (i.e., non-asbestos organic type) brake pads.
With the rapid development of modern technology, like the other components of the braking system, like brake pads themselves in recent years been continuously developed and variations.
In the conventional manufacturing process, the friction material on the brake pad for use in a variety of binder or mixture of additives, and wherein the insertion of the fibers to increase its strength, plays the role of reinforcement. Brakes on the manufacturer published on the use of new materials, in particular formulations often secretive, of course, some ingredients such as ingredients: mica, silica, rubber debris is disclosed. The net effect of the brake pad braking, wear resistance, temperature resistance and other properties will depend on the relative proportions between the different components. The following will briefly talk about several different materials of brake pads.
asbestos brake pads
from the beginning of asbestos it has been used as a reinforcing material of the brake pads, since asbestos fibers having high strength and high temperature characteristics, and thus meet the requirements of brakes and clutch disc pads. This fiber has a strong tensile capacity, or even can be matched with the high-grade steel, and can withstand temperatures of 316 ℃.More importantly, asbestos is relatively cheap, it is extracted from the amphibole ore, and such ore have been found in large quantities in many countries.
In the composition ratio of asbestos in brake pads, asbestos accounts for 40-60 percentage, but found that most people now have potential hazards of asbestos, asbestos has been shown to be carcinogenic medical profession, its needle-like fibers easily enter the lungs and remain, resulting in stimulation, may eventually lead to lung cancer, but this disease incubation period of up 15–30 years, so people tend to know less than the harm caused by the asbestos.
as long as the asbestos fibers are fixed upon themselves do not cause harm to the health of staff friction material, but when the asbestos fibers along with the formation of brake dust and brake emissions, it may become a series of health effects roots.
According to the test the US Occupational Safety and Health Association (OSHA) made, once for each routine test of friction brake pads will produce many millions of asbestos fibers into the atmosphere, and this kind of fiber is far smaller than a human hair, the naked eye can not be observed, it is possible to breath inhaled asbestos fibers while thousands of people are unaware. Similarly, if the brake pipe air brake or drum brake member in the dust blown off, but also numerous asbestos fibers may be blown in the air, and the dust will not only affect the health of the technicians work, will also any the presence of others cause health damage. Even some very simple operation such as: a brake drum with a hammer so loose, so that the brake dust inside out, a large amount of asbestos fibers may be blown air. More worrying is: Once the fibers floating in the air continued for several hours, then they will stick on clothes, on your desktop, tools, everything you can think of on the upper surface of the object. Any time but encountered a stir (such as cleaning, walking, air flow is generated when using pneumatic tools), which in turn will be re-floated into the air.
Typically, once this material into the environment, it will stay as long as several months or even years there, working there for staff and even customers pose potential health effects.
US Occupational Safety and Health Association (OSHA) also states: asbestos fiber content of people’s work environment is not only more than 0.2 per square meter is safe, routine brake at the same time should be reduced as far as possible maintenance work produced asbestos dustAvoid dust may cause release of work (such as hammering brake pads, etc.).
But in addition to factors outside the health hazards of asbestos brake pads, there are still another important issue. Because asbestos is adiabatic, the heat capacity is particularly poor, heat will generally be used repeatedly stacked in the brake brake sheet, the brake pads heat up, it is necessary to change the braking performance occurs, to produce the same braking force and friction will require more dislikes brakes, a phenomenon known as “brake atrophy,” if brakes reaches a certain temperature, it will lead to brake failure.
When the vehicle manufacturers and material suppliers braking decided to develop new, safer alternative to asbestos, a new friction material emerged almost simultaneously. This is discussed below to “semi-metal” type and a mixture of non-asbestos type organic (NAO) brake pads.
“semimetal” mixture brake pads
“semimetal” mixture brake pads (Semi-met) is mainly used coarse steel wool as reinforcing fibers, and important mixture. (Fine particles and fibers) can be easily distinguished from the appearance of the type of asbestos and non-asbestos brake pads organic (NAO) region, they also have some additional magnetic.
The steel wool has a high strength and thermal conductivity, which makes the “semi-metal” mixture brake pads have different braking characteristics to conventional asbestos brake pads. For example: high internal metal content “semi-metal” pads and high strength, high metal content also changes the friction characteristics of brake pads, generally it refers to “semi-metal” pads require higher brake pressure to accomplish the same braking effect. Especially in a low temperature environment it means that the same high metal content will cause a larger brake pads or brake disc wear of the brake drum surface, it will produce more noise.
The main advantages of the “semi-metal” mixture brake pads (Semi-met) is its ability to temperature control and higher braking temperatures, with the difference between the heat transfer performance of asbestos-type disc brake, Ltd. the cooling capacity of the stationary drum inferior they help brake discs and the brake drum when the heat out from the surface thereof, heat is transferred to the brake caliper and its components. Of course, if the heat also cause problems not handled properly, the brake fluid heating temperature rises, if the temperature reaches a certain level, it will cause the brake and brake fluid boiling atrophy. This heat while the caliper, the return spring and the piston seal also has some influence, will accelerate the aging of components, which is when the brake caliper To reassemble the maintenance and replacement reasons the metal member.
type organic non-asbestos brake materials {NAO)
type organic non-asbestos brake materials are mainly glass fiber, aromatic polyester fiber cool cool or other fibers (carbon, ceramic, etc.) is used as a reinforcing material, its properties depending on the type of fiber and other additives mixtures thereof.
non-asbestos organic material is mainly used as an alternative brake asbestos crystal developed for the brake drum or a brake shoe, but more recently they are also beginning to be used as the front disc brake pads try alternatives . In terms of performance, NAO asbestos brake pads closer to the brake pads, rather than semi-metallic brake pads. Unlike semi-metallic brake pads as having good thermal conductivity and good temperature controllability.
The new NAO raw materials and asbestos brake pads different? Typical asbestos-based friction material containing five to seven kinds of base mixture, which comprises reinforcing fibers of asbestos, a binder and various additive materials such as linseed oil, resin, a wake intoxicated benzene, resin.
In comparison, NAO friction material comprises 17 different profiles polymer material around the stick, because the asbestos is not equivalent to remove simple replacement of an alternative to, the need to ensure a large number of brake mixture properties, so that the braking effect over flat or asbestos friction block.
material NAO brake pads has undergone several changes, now NAO material in many areas has been effectively exceeds the performance of asbestos brake pads, mainly in the areas of anti-friction performance and noise.
Of course, the standard specification should be finalized first, because the only way to test any new friction material formulations. These specifications include friction properties, resistance to fatigue, temperature tolerance, wear resistance and noise. Friction and better performance of the friction material block at different temperature and pressure is kept better, in other words, at low or high temperatures, which properties should be little change. Better friction material, the more unlikely to shrink after repeated braking brake, which makes the “brake pedal feel” good. Better materials will also reduce wear and reduce noise. Earlier NAO brake pads only reachedWhich requires part, but now has been basically fully achieved. Today’s NAO brake pads than life significantly prolonged asbestos brake pads, drum brake at the same time also help prolong the life of the brake disc.
6, the principle of replacement brake pads
Replace the brake piece, it is best to use a high-performance brake pads, although the price ratio economy brakes higher, but the material is much better, longer service life, of course, safety should be much stronger, therefore, temporary high-tech people will definitely return for more in return.
need to remind owners: Replace the brake piece to be used as much as possible with the old brake pads have the same material, of course, can do high if new brake pads material than the original material on a better level. Replacing the brake piece of different materials only follow the following two principles only to ensure their safety.
1, try not to use NAO material to replace the brake pads half-metal material.
2 can replace asbestos brake pads of the NAO material.
Replace the brake pads cycle
replacement cycle brake pads, often dependent on operating conditions, the type of vehicle, vehicle weight, brakes of the type of vehicle to specific circumstances It may be. For example, among the real-life situation often it is: A 50000 or 60000km brake pads can be used on a car, and perhaps use only 25000km on another vehicle must be replaced. Frequency and vehicles parked on the road trip is an important factor, in general, long-term replacement cycle on city streets in vehicles whose brakes are significantly shorter than the long-term vehicles on the highway, on the mountain road than flat road running short, short truck off than light rail replacement cycle. So, in fact, no “authority” brake pads can say clearly in the end to how long, only one thing is sure – should always check the wear of brake pads.
The timing of replacement brake pads
generally in the following cases, the brake pads must beReplacement: 1, when the thickness of the brake pad is less than the vehicle manufacturer allows minimum maintenance standards; 2, when the wear indicator tab on the brake pads contact the brake disc; 3, brakes are when oil or grease contamination; 4, brakes when abnormal wear or taper wear.
In general, if the thickness difference on both sides of the brake pads fixed caliper reached 15mm, the thickness of the brake pads on both sides of the differential floating caliper need to be replaced when reached 3.0mm. Of course, just can not accurately determine whether the brake pads wear through simple appearance observation, it should generally use a ruler to measure the thinnest brake pads to see if within the allowable range (typically should be based on specific models maintenance manual).
7, automotive brake operation of the market industry analysis
the development of brake pads products in the market demand growth is closely related with the automotive industry (vehicle production and ownership determines the production of brake pads, and brake it there is a strong positive correlation) between the film production and sales, the rapid development of China’s auto industry will be directly contributing to the simultaneous development of brake pads manufacturers. First, China is about more than 300 car manufacturers, car tuning high reached more than 600, with an annual output of about 19 million vehicles, brake pads market in great demand, the country’s annual demand of about 500 million sets of brake pads.
8, four methods is determined whether the brake pads need to be replaced
1, see thickness: the thickness of a new brake pads generally about 1.5cm, with the use of constant friction in thickness It will gradually thinning. When visually observed when the remaining brake pad has a thickness of about 1/3 of the original thickness (about 0.5cm). The owners will increase the frequency of self-test, ready to be replaced. Because there are individual models wheel design reasons, do not have the conditions to the naked eye to see, the tires need to be removed to complete.
2, the intensity of feeling: the brakes while driving on the road, if you feel very difficult, there is always a soft feel, often need to step on the brake to reach ever deeperThe braking effect when taken out of the emergency brake pedal position will obviously feel low, then there may be a friction brake pads has basically been lost, and this time must be replaced, otherwise it will lead to a serious accident. Further reducing the braking effect will lead to increased brake fluid consumed, while the replacement of brake pads to focus the inspection brake oil.
3, listen to the sound: if accompanied by “rub Iron Iron” hiss at the same time or tap the brake squeak (there may be effect at the beginning of brake pads mounted running-produced), At this time, the brake pads must be replaced immediately. Since the limit has been identified on both sides of the brake pads direct friction brakes, brake pads proof limit has been exceeded. Flag both sides of each brake pad has a projection, the thickness of the mark is about twenty-three mm, which is the thinnest limit replacement brakes, if the thickness of the brake pads has parallel to this flag, it must be replaced. So when the thickness of the brake pads closer to the flag when the owner must always observe the ready, but without removing tires accurately observed by the naked eye is difficult, it is recommended to 4S store or repair shop regular checks to determine whether the need to replace .
4, to see if the instrument panel brake warning lights should never change as determined according to the brake pads. Some high-end cars will have a brake warning light and the alarm line generally only the front brake brakes only. When warning lights, then only if the change has been very dangerous. Because this warning system either directly sensing the thickness of the brake pads, while others are completely finished brake pad wear, brake oil drops so extreme, will make warning lights. If the latter, until the warning lights, brake pads and the brake disc is already in the base metal iron sharpens iron status, then, near the edge of the rim will be seen in bright cut tire iron. Therefore, we recommend regular check brake wear status to see if it can, but do not just take warning lights.