Standardization of passenger car disc pads

With the automotive market changing rapidly to keep up with customer demand and technology developments, the heat is on for the brake pad business. This blog will explore the standardization of brake pads as one of the major trends in the brake pad market (along with reducing environmental effects, and the introduction of electric vehicles).

Standardization of the passenger car disc pad (PCDP) can be approached from three different angles: globalization, type of propulsion, and car platform. All three have their own time frames, challenges and market opportunities.

Car and brake manufacturers therefore have different approaches. Usually, the largest benefits are manufacturing efficiency and cost reduction.

Cars around the world have different brake pads depending on where they drive. With asbestos having been phased out, the brake pad market is now divided into two formulations. A low steel formulation based on steel fibres has high performance, and is used in most of Europe and South America. Cars with low steel brake pads can easily be recognized by looking at the rims, since they typically leave a layer of dust on the (front) rims of the car. South east Asia and North America use a less abrasive formulation called NAO or Non-Asbestos Organic.

The brakes are one of the most complex stations of a car production line. Cars destined for various regions are made on one production line, so the disc pad formulation has an impact on logistics, inventory and variations. All these add cost and complexity to the manufacturing process.

Car makers want one standard formulation, style which can withstand the high performance tests like the European AMS test while also offering the Far Eastern and North American braking comfort. This best of both worlds is known as a hybrid or Global NAO formulation.

Global NAO brakes can already be found on the rear brakes of some car platforms.

To extend Global NAO, brake pad manufacturers have to find ways to increase NAO pad friction levels while meeting Noise, Vibration and Harshness (NVH) requirements. Only then can brake pads be standardized across regions to reduce manufacturing and logistics costs.

A first factor is oxidation. A brake pad and rotor will oxidize. Every time the brakes are applied, the car not only decelerates but also cleans the pad and rotor. A brake pad that is not used as frequently has a higher likelihood of oxidizing. Software in cars with an electric engine can now be programmed to use brake pads instead of regeneration for this reason. This does however reduce the range of the car. 

Besides oxidation, the size and weight of the brake pads and rotors are also important.

An electric version of a car is typically heavier than its combustion engine version because of the batteries. For emergency braking, it will therefore need more brake pad surface area to decelerate the car since regenerative braking will not be enough. This would mean brake pads for electric cars need a higher surface area, so a pad (including back plate) would typically be heavier.

Already, a brake pad including back plate weighs around 350-375 grams. With eight brake pads on a car, and each brake pad having a caliper, a larger surface area would give substantial additional weight which would reduce driving range. But, since the brake on an electric car is used less often, that gives an opportunity to make the pads thinner. This would save weight not only on the brake part but also on the parts connected to it.

When it comes to propulsion, car makers will have to tradeoff between diversifying their portfolio and over-specifying brake pads. So far, we have seen car makers using different approaches to tackle this dilemma, which will continue to grow.

The diversification in propulsion is particularly interesting since it influences not only deceleration but also range and service costs of cars and models.

Diversification of brake pads on passenger cars can happen along the three axes described in this blog: globalization, propulsion, platform. Car manufacturers – and their suppliers – will need to focus on standardization of parts like brake pads to reduce development, inventory and production costs while at the same time using economies of scale.

_{Figure 1 - PCDP diversification is occurring along three axes.}

Standardization always comes with sacrifices for customization. It is a continuous balancing act for car makers who will demand high performance brake pads.