Brake pad testing laboratories
With the development of the automotive industry, understanding the performance of the car has also become very important, especially the braking system, which is related to the safety of people. In different tests, by analyzing the brake system and different standards, the performance of the car is evaluated and the required information is obtained. The results of the car brake pad test form the basis of fault diagnosis and repair.
There are 5 million accidents every year, and a 20% reduction means one million fewer accidents, so the urgent need for rigorous and standardized testing has become a must. Therefore, due to the importance of vehicle safety and the protection of the lives of occupants, new vehicles today must comply with vehicle safety standards. For example with the standard (FMVSS 105) which determines the maximum stopping distance according to weight, load, pedal efforts (with and without auxiliary brakes) and braking conditions.
There have also been reports of a number of requirements for testing braking resistance, as well as separate tests for noise or corrosion of the pad.
Since 2000, the standard (FMVSS 135) has found its place. These standards are for the original brake system that is installed on the car during production, and spare parts factories do not follow these standards.
Another point is that both 135 and 105 standards are in fact the minimum standards required to confirm brake performance. Many cars easily accept these standards and a positive test brake test result, and many find it difficult.
Brake pad standards and conditions
Every new material that enters the world of pads must be physically and mechanically tested and its Tribological properties determined in order to see if it can transform the automotive world.
During braking, the contact between the disc and the pad is approximately 80%, which according to ECE R90 standards, all pads used in continental Europe must comply with this standard. Lenses that meet this standard have the letter E engraved on the edge of the pad with a code indicating which authority or laboratory has approved it. For example: UK- ‘E11’ which is made in the United Kingdom.
In general, these codes indicate the manufacturer’s ID, pad type, and alpha mark, which indicate the wear characteristics of the pads. The importance of these codes is that they indicate what kind of materials the pad manufacturer used and whether or not they met environmental standards. For example, if the edge code of the pad is as follows:
DB9387FF
4911P430
The DB indicates that the pad is made by Roulunds Braking and the rest of the numbers are issued by AMECA. Indicates heat (temperature 600 degrees Fahrenheit).
If the level of coefficients of the part you buy does not match the original sample, it can not provide proper performance and will correct the brake at that temperature.
For example, on all American and Japanese pads, you can see the following code with the description of the subject:
Pad edge code Brand name Vehicle type
Front: DEL TK-FE
Rear: DEL TK-FE AC Delco Affinia-BPI Dodge Charger
Front: DEL TK-FE
Rear: DEL TK-FE AC Delco Affinia-BPI Ford CVPI
Front: SD 9008-FF
Rear: DMJ 720-FF Napa Ultra-Premium Rayloc Ford CVPI
Front: K079A
Rear: K079A Dan Block GRI Engineering
and Development
LLC Impala
The description of the last two letters on the universal standard pads, which are in fact the coefficient of friction or abrasion of the pad, is as follows:
• Friction or abrasion coefficient pad code at 250 F and 600 F descriptions
• EE friction coefficient at 250 and 600 F: 0.25 – 0.35 This type of pad can brake at 600F.
• FE means the coefficient of friction at 250 and 600 F is as follows: 0.25 to 0.35 @ 250 F
0.35 to 0.45 @ 600 F The probability of braking this type of pad at 600F is between 2% – 44%.
FF means the coefficient of friction at both temperatures 250 and 600 F is as follows: 0.35 – 0.45 The probability of braking this type of pad at 600 F is approximately 2% -22%.
• GG means the coefficient of friction in two temperatures of 0.45 – 0.55 rarely brakes.
HH The coefficient of friction in both temperatures is 0.55 – 0.65, so at 3000 F there is no problem.
Code: 082461 N16, which N indicates that this pad is 0.5% by weight of copper and was produced in 2016.
The numbers after the letters A, B, and N indicate the date the pad was made and must be marked on the box in the United States.
A = is designed to have the least amount of cadmium, chromium, lead, mercury and asbestos.
B = means 0.5% – 5% by weight of copper and is in accordance with certificate A.
N = less than 0.5% by weight of copper and also according to certificate A.
In different field tests, after each brake pad test, drivers are asked the same questions, and if their answers are the same, they consider it a significant result of the pad performance. Sometimes, though, these answers seem like a taste.
Brake pad test methods in the laboratory
Testing the properties of pads requires sensitive and delicate methods, because their properties can not be guessed on the basis of chemical structure, appearance or other information about the properties of metals and alloys, but can only be proven by certain experimental methods. The abrasive properties of the brake pads depend on several operating conditions, including temperature, surface pressure and slip speed.