With a number of countries and states recently issuing declarations regarding future electric vehicle mandates, it's becoming increasingly clear that society is shifting its focus toward health and environmental stewardship.
When it comes to automobiles, much of the attention is focused on reducing the overall carbon footprint of consumer driving behaviors. Fuel sources aside, other areas of the automobile industry are also taking steps to become more eco-friendly. This includes brake manufacturers, who are turning an eye toward reducing the environmental impact and health risks associated with traditional brake materials.
What's the problem with traditional brake materials?
Braking is an integral task of driving, and unfortunately the "brake dust" generated by traditional components of vehicle braking systems contributes significantly to the overall environmental particulate matter expended by vehicles.
Particulate matter is formed when particles, such as those from wear and tear of brake components, combine with air droplets. There are several sizes of particulate matter, but those of primary interest to the United States Environmental Protection Agency (EPA) are designated PM10 and PM2.5. Of the two, PM2.5, also known as fine particulate matter, is more worrisome due to its impact on air quality, which is why it is the primary form of particulate matter regulated by the EPA.
Brake dust can contribute to both large and fine particulate matter, depending on a number of factors, including the specific material used in the friction-creating regions of the braking system as well as the braking mechanism. Past research showed that copper particulate, previously a major component of brake pads in the post-asbestos era, caused a marked inflammatory response in human lung cells, as well as a significant impact on the environment. As a result, two states, California and Washington, passed legislation requiring a decrease in the amount of copper used in brake pads, which forced companies to begin looking at other materials as possible replacements.
What are the alternatives?
Brake companies are pulling out all of the stops when it comes to experimenting with new materials to increase wear resistance and decrease shedding of toxic brake dust.
Ceramic brake pads are perhaps the most common modern day alternative to metal blend formulations. Benefits of ceramic brake pads include a significant reduction in brake dust compared to metal blend pads, as well as noise reduction and a firm feel when braking. One of the major drawbacks, however, is cost; ceramic brake pads can be more expensive than those made of other materials.
Fortunately, the industry's focus on brake pad materials science has yielded products with a wide range of alternative composition, including those made of Kevlar, fiberglass and aramid (aromatic polyamide). These products are held together with various types of resin, and referred to as organic brake pads. While they are more affordable than their ceramic counterparts, the organic brake pads also tend to wear out more often.
In addition to altering the composition of brake pads, product designers have also been working toward development of alternative braking mechanisms. Two are discussed below.
Future direction of brake technology
While drum brakes have been somewhat marginalized by disc brakes, there has been renewed interest in their utility thanks in part to the potential for a closed system that reduces production of particulate matter. It has been suggested that drum brakes might be a viable solution for both gas and electric vehicles; particularly, the rear axle of electric vehicles and front axle of many others.
Another area of emerging interest has been in the development of so-called fluid brakes, which utilize electromagnetic forces to help slow and stop vehicles. These brakes do not wear in the same way as traditional disc brakes, helping to greatly reduce the production of brake dust.
Conclusion
Moving beyond asbestos and copper to ceramic and organic components, brake manufacturers are looking harder than ever at ways to reduce production of toxic, environmentally destructive brake dust. It has become readily apparent that we cannot continue breathing in the particulate matter from the dust generated through traditional means of braking, nor letting the dust and shavings contaminate waterways. Through advances in braking technology and materials science, it appears more sustainable and health-conscious options are in our future.
Greening Testing Laboratories is a fully certified brake testing lab that provides a variety of brake testing services worldwide. Contact Greening for a complimentary consultation.