Emission Standard Euro 7: Seven Questions About Brakes

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FAULHABER Drive Systems

Wuxi InfiMotion Technology Co., Ltd.

At the end of November 2026, Euro 7 will take effect. The regulation limits brake particle emissions. What does this mean for pads and discs?

From November 29 of this year, newly homologated vehicle models may not release more than seven milligrams of brake wear per mile into the environment. For battery-electric vehicles, the limit is only three milligrams. From November 29, 2027, this requirement will apply to all new registrations.

This is the first time air pollutants are addressed that do not originate from the drivetrain or exhaust—which is why one should now refer to an emissions standard rather than an exhaust standard.

We asked several manufacturers and suppliers of brake components what the new standard means for the design and production of brake pads and discs. We thank the companies Aumovio, Brembo, Forvia Hella, TMD Friction, and Zimmermann for their responses.

What is the Share of Emissions from the Brake Disc And Brake Pad?

The proportions of fine dust emissions attributable to the brake disc and the brake pad strongly depend on the friction pairing used. For a classic friction pairing, predominantly used in Europe, consisting of a cast iron brake disc with a "low-metallic" ECE brake pad, studies show a high iron content in fine dust emissions. The iron content can range from 70 to 90 percent. Accordingly, the main component of fine dust emissions is the wear of the brake disc.

Will New Technologies Be Necessary to Meet Euro 7? If So, Which Ones?

Different friction pairings are required for different vehicle platforms and drive concepts. For example, small, lightweight electric vehicles often only need an adjustment of the brake pad towards less abrasive material combinations to meet the Euro 7 standard.

Large vehicles can meet the new Euro 7 requirements by using a brake disc subjected to a ferritic nitrocarburizing heat treatment (NFC) and a corresponding adapted brake pad. For large, heavy vehicles with combustion engines, the use of hard-coated brake discs and matching brake pads is necessary. The coating is typically made of stainless steel mixed with titanium carbides. Other options include tungsten carbide or Verocrom. These coatings have a surface hardness up to ten times higher than cast iron.

An alternative development approach focuses on the brake pad, making it less aggressive to reduce wear on the brake disc. This often involves the use of NAO brake pads, "Non-Asbestos Organics," which operate on the adhesion friction principle. In contrast, traditional "low-metallic" ECE pads operate abrasively.

An example of Euro 7-compliant brake technology is the "Greentell" set by Brembo. The brake disc features a two-layer, nickel-free coating applied using laser metal deposition. Combined with the corresponding brake pads, it reduces surface wear by 80 percent compared to an uncoated cast iron brake disc. Additionally, some OEMs are testing closed systems such as drum brakes to structurally reduce fine dust emissions.

Are There Conflicts of Interest Between Corrosion Protection And Euro 7?

When using traditional friction pairings, a clear conflict of objectives currently arises. For electric vehicles, highly abrasive friction pairings are currently used to remove rust that forms on the brake disc even with lower friction performance. However, this increases the generation of fine dust. Alternatives include the aforementioned hard-coated or FNC-treated brake discs. Both solutions offer excellent corrosion protection.

What Are the Consequences of Euro 7 for Pure Aftermarket Parts?

The pairing of the brake disc with the respective friction pad gains importance under Euro 7, as they are tested in combination and the limits apply to the pairing. Replacing only one component may, therefore, no longer ensure compliance with the limits. This will present a particular challenge for the aftermarket and significantly restrict interchangeability, Hella notes.

The question of how aftermarket parts will be approved for the market in terms of their emission properties has not yet been conclusively clarified. According to Aumovio, the issue is currently being discussed in various committees so that independent aftermarket parts suppliers and wholesalers have clarity on how their products can comply with the new regulation.

Will Brakes for Electric Cars Differ from Other Brakes in the Future?

According to TMD Friction, the highly electrically assisted braking of electric vehicles presents new opportunities for materials that were not suitable for conventional vehicles due to insufficient performance. For example, stainless steel would be a suitable material for the brake disc to protect against corrosion. Other materials that are hardly susceptible to corrosion could also be considered, such as aluminum.

Aumovio is working on lighter brake components. The so-called "green" floating brake calipers for electric vehicles are more compact and lighter than those in conventional vehicles—while maintaining identical braking performance. With this new design, the brake caliper can be up to two kilograms lighter, and the brake disc even up to three kilograms.

Do Brake Pads for Electric Cars Have A Thinner Friction Layer?

Aumovio: When brake systems are developed for a purely electric vehicle platform, the advantages of recuperation can also be utilized in the design of the friction brake. If less total frictional performance needs to be realized in the pad, brake pads or the friction material used can be made thinner.

Forvia Hella: At present, we are not making targeted adjustments to the pad thickness specifically for electric cars. In principle, it would be conceivable to save material due to the reduced strain on brake pads from recuperation. However, the pad thickness in our development and during reverse engineering is always based on the specifications of the respective OEMs.

TMD Friction: In individual cases, this is practiced.

Will Electric Cars Have A "Lifetime Brake" in the Future?

Fundamentally, this is conceivable, says Aumovio. However, there are two technical challenges that stand in the way: corrosion and wear. As previously mentioned, the corrosion protection of the brake disc can be improved through coatings. The wear of these brake discs is low enough that they can be used for "lifetime brakes." However, such a brake disc is significantly more expensive than traditional designs.

The wear of brake pads is also significantly lower compared to uncoated brake discs, by a factor of 2 to 3, but is currently still not in the range of "lifetime brakes" with up to 186,000 miles.

In the future, the main reason for replacing brake discs will be less due to wear of the friction partners and more due to aging effects such as rust in the cooling fins or possible cracks in the coating that promote corrosion. According to TMD Friction, it is conceivable that vehicle manufacturers will specify replacement after a certain mileage or operating time—whichever comes first.

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