This is the first of a series of Lapinus blogs highlighting the most important trends facing the manufacturers of cars, brake systems and brake pads. The entire blog can be read by clicking on this sentence.
You can’t cut corners when manufacturing car brakes. Huge stresses are concentrated on small surface areas every time a car brakes – tens of thousands of times over a pad’s life. Pads must keep giving the same pedal feel and smooth deceleration in all conditions.
In a slow-moving and safety-conscious industry, demands are changing quickly, particularly faced with new emissions laws and regulations. Friction material compounders must develop different formulations with alternatives to copper and other raw materials for H&S reasons.
Lapinus’s recent introductory article discussed the trends in automotive braking. Here, we’d like to expand on three areas that are most important to car and brake system manufacturers: reducing brake wear and emissions, standardizing pads globally, and electrification and driver automation.
Brake pad wear and emissions continue to reduce
Research is continually reducing brake pad wear, which is also important to reduce brake emissions. Over 90 percent of PM10 particulate matter emissions from traffic are now estimated to come from non-exhaust emissions. Up to half of that comes from brake wear, and legislation for emissions is being written in various countries and regions right now.
The legislation will most likely include details of particle sizes and possibly emissions chemistry. Car manufacturers are working closely together with legislators. Once legislation is introduced, it will set up a chain reaction where the car manufacturer has to comply, and this may change requirements for brake pads.
In the short term, filters or vacuum pumps could reduce emissions to legal levels while longer-term solutions are worked on. At the moment, though, the extra weight makes manufacturers reluctant to add them, and filters are inconvenient when replacing brake pads in the aftermarket.
Standardizing brake pads and Global NAO
Different legislation in different geographic regions is making life difficult for car (and brake-system) makers. Car manufacturers are increasingly looking to avoid the expensive process of customizing production lines for the different regions. European cars at the moment need low-steel (LS) brake pads that incorporate steel fibers. U.S. and Asian brakes instead use non-asbestos organic (NAO) also called ceramic friction materials.
LS pads have a higher friction coefficient and therefore the shortest stopping distances but score less on comfort. NAO materials have zero steel content, have a lower friction coefficient, but better comfort. A NAO pad for example doesn’t result in dirty rims which are common in Europe.
NAO materials give less disc wear, and tend to have better NVH (noise, vibration and harshness) particularly near end of life, and can be reinforced by materials like Lapinus’ mineral fibers. These fibers are (uniquely) certified bio-soluble and completely safe for humans and the environment.
The future of brake pads lies in a global NAO standard. A normal combustion-engine car has 60-70 percent of its weight on the front wheels. Stresses are therefore particularly high on the front brakes, and these absorb most of the braking energy. The first global NAO brake pads will therefore target the rear axle of smaller vehicles.
One obstacle holding back global NAO is European-focused legislation. The AMS (Auto, Motor and Sport) test sets the bar high when it comes to stopping under extreme conditions. AMS is widely accepted for maintaining safety, even with end customers, but is hard to achieve using NAO brake pads.
However, more intelligent sensors in cars and a push towards lower maximum speeds on European roads could change this perception. In future, the test could be seen as over specified for normal traffic, which could open up the market for global NAO.