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Case studies / Friction
Where are we coming from? From Asbestos-based to NAO Copper-free
A joined effort among manufacturers, regulatory organizations and the automotive industry has brought a noticeable evolution on the composition of the friction materials

All machine in movement needs to be stopped at some moment. The brake is responsible to turn this kinetic energy into heat and release it through the interface.

This is the everlasting basis of the friction industry. Actually, during a normal braking, the disc is responsible to dissipate around 80 % of the heat generated by friction. The temperature can raise up to 600-700 ºC in rough conditions. As a result of the energy involved in this process, tribo-chemical reactions and erosion always take place.

The chemical composition of the brake PAD then, is directly related with the performance of the whole brake system.

Every time you stop your vehicle, a small amount of material is released in form of PM10 and PM2,5, small enough to be caught in air turbulence and easily enter human airways.

Depending on their composition, can be quite harmful to wildlife as they might contain metals such as copper, chromium, lead, antimony and metal oxides.

Considering that around 21% traffic-related PM10 emissions come from brake wear, automotive industry, raw material manufacturers and regulatory organizations have a shared responsibility to follow up dust emissions released during braking, and come up with innovative solutions to overcome this environmental threat.

Up to the 1980's - Asbestos
Asbestos linings were used on virtually all vehicles. Asbestos was and still is an excellent fibre for brake linings. It offers good strength, temperature and chemical resistance, and is cheap compared to other materials that are used for the same purpose. But the physical properties that make asbestos such a good fibre also make it a hazardous substance, as it can produce asbestosis.
Metal-based materials
The arrival of front-wheel drive required semi-metallic front disc brake pads that could withstand higher operating temperatures. But they had their own troubles, such as the increase of noise and vibrations, and also the amount of grey/black dust produced. The industry evolved to offer a wide range of additives to equilibrate the formulas depending on the application and reduce these drawbacks.
NAO and Low-met
Manufacturers started also to develop formulas with lower and even none content of steel (NAO) using alternative reinforcement materials such as rock wool, polymeric fibres and non-ferrous metals.

Copper, brass and bronze became materials of general use because of their contribution to the performance and wear at high temperature and also because of their good NVH properties, and where in the origin of RIMSA as supplier for the friction industry, providing high quality recycled chips of brass and bronze.

At rimsa we were pioneers on manufacturing lead-free brass and bronze chips 20 years ago

On the other side, recyclability regulations in the latest 1990´s for vehicles in Europe (End-of-life directive 2000/53/EC) states a maximum content of metals such as Pb, Hg and Cr(VI) <0,1 %. and Cd <0.01 %. Friction materials were a source of Lead. It was common to use lead sulphide as lubricant and lead derivatives were regular contaminants in natural products such as pyrite (natural FeS2), sometimes up to 10%.

Since more than 20 years ago, our unique manufacturing process enables us to offer the OE’s choice of lead-free CHIPS with the best value-for-money.

These are the products used in this case, go take a look at its specs
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