In 2019, the government’s Air Quality Expert Group said particles from brake, tyre and road surface wear directly contributed to over half of particle pollution from road transport, so what measures are Juratek taking to reduce the harmful particles in friction materials? Bradley Hill, the company’s engineering and quality assurance manager, explains.
It is obvious that the action of two surfaces rubbing together, like brake pads on brake discs or tyres on the road, will cause wear to both surfaces.
In the case of brakes, about half of this wear debris is released into the air, some of it is dispersed to the roadside and the rest sticks to the wheels of the car and vehicle body in close proximity to the car’s wheels – we have all experienced the ‘dirty wheel’ problem with our alloys!
As a result of this, both California and Washington states have imposed regulations to reduce copper and other heavy metals from being present in braking products. The first level of the legislation began in 2014 in California and 2015 in Washington. All brake manufacturers and importers were required to self-certify that their brake pads contained no more than 0.1% by weight of asbestos, cadmium, chromium, lead, and/or mercury.
In January 2021, the second phase of the legislation came into effect; brake manufacturers and importers must selfcertify that their brake pads contain no more than 5% by weight of copper. By 2025, this must be less than 0.5%.
This law does not apply in Europe; however, the principles behind this law are to everyone’s benefit – reducing harmful pollution is good news for everyone.
Juratek worried about health and environment effects
Like others in industry, Juratek has been rightly concerned about the health hazards that might be posed by this brake wear debris, and for some years now our range of brake pads has been fully environmentally friendly, with all of our pad materials being free from heavy metals and copper. This presented our product development team with a significant challenge: to ensure our products still had excellent standards of performance and freedom from noise and judder, whilst retaining reasonable pad and disc life. In summary, our aim was to ensure Juratek pads provided premium service performance, without costing the earth!
Governments are looking to go further than just restricting the use of some of the more problematic ingredients of brake pads; it has been established that this wear debris, or particulate matter, which is a mixture of both pad and disc debris, ranges in particle size from > 100 μm to approx. 0.1 μm, with some of it falling in the critical respirable range of 10 μm to 1μm. (PM10 & PM2.5)
To reduce particle emissions further will require a much broader approach across a number of fronts, so we are seeing special hard coatings being applied to the surface of brake discs to reduce their wear rates and, of course, carbon-ceramic discs offer reduced wear, albeit at a significantly higher cost.
The automotive industry is also exploring partially enclosing brakes and fitting them with filters, in order to capture the bulk of particulate emissions, so the likely final outcome will be a combination of measures.
