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The following is a report prepared by Meritor on the company’s development of a new brake pad material – what they have named N-type brake friction formula – which already meets the strict 2025 copper-content (and other materials) legislation by the U.S. states of California and Washington.
When the destination is clear, there’s no point in delaying the arrival.
That is the philosophy that drove Meritor to be the first heavy duty brake manufacturer to meet the Better Brakes Law 2025 standard for copper content in brake pads.
In 2010, the States of California and Washington enacted legislation that will require brake pads sold or installed in both states to have reduced levels of copper and other heavy metals. The law calls for reducing copper in brake pads to <5% by weight in 2021 and 0.5% by 2025. In addition to copper, the voluntary initiative reduces mercury, lead, cadmium, asbestiform fibers and chromium-6 salts in pads. This, in turn, should reduce runoff of these materials from roads into waterways, where they harm plants and wildlife.
“Our new disc brake MA frictions offer OEMs and fleets a solution today that complies with the 2025 laws,” said Saad Malik, general manager for Front Drivetrain at Meritor “Our friction saves OEMs the time and expense of validating brake pads multiple times for various applications and weight ratings and offers the industry a green solution.”
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Meritor got to work soon after the agreement was signed. The company began looking for a new N-type brake friction formula that would allow for less copper, without affecting brake performance.
It was not a simple solution. Friction formulas have four main functional groups, each of which contains up to 20 different elements or compounds:
- Fibers – These offer structural integrity. Copper is an element. Its length, width, hardness and strength can be modified to fit specific formula requirements.
- Fillers – Elements used to provide proper spacing for other elements. Copper is not used in this group.
- Friction modifiers – These provide the desired friction mu characteristics necessary for consistent braking behavior. Copper provides friction stability as well as thermal conductivity to distribute energy during a stop. It also helps develop a transfer layer, a thin film between the rotor and pad which supports friction mu and wear characteristics.
- Resins – This binds all the ingredients together. No copper involved here.
Changing one ingredient in the formula can affect all the others, said Joe Kay, director of engineering for brakes with Meritor. He compared it to a cookie recipe.
“Just like any recipe, one of the ingredients can be replaced by another,” said Kay. “If one ingredient is changed, it will likely affect something. It could affect the taste, or the smell, how brittle it is, how flat it becomes, if it sticks to the pan or many other issues. The same thing has to be developed in brake pads when we eliminate the copper.”
In other words, the search was for a substitute formula that does everything the copper-containing one does.
“It was not easy because it takes hundreds of tests to get things just right,” Kay said. “Probably the biggest challenge is assuring the wear life is going to meet the customers’ expectations.”
Meritor spent approximately two years testing different formulas, progressing from laboratory to FMVSS test tracks to fleets.
“We need at least two years in service with lots of samples in order to make a final judgement if the formula meets all expectations,” said Kay. “Sometimes we may find a formula is not good enough after spending two years in development.”
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In the end, the MA9300 friction demonstrated superior pad wear and similar rotor life compared to Meritor’s current offering during two years of comprehensive lab validation and more than 2.4 million miles of field testing, Kay said.
Today, N-level friction for all Meritor disc brake products, EX+™ LS, EX+™ L, EX+™ H and Quadraulic, is 2025-copper compliant, including MA9300, MA9500 and MA704, for truck and trailer applications.
