Tech Briefs Magazine - May 2024 - 37

SPINOFF
J
ust as NASA needs to reduce mass
on a spacecraft so it can escape
Earth's gravity, automotive manufacturers
work to reduce weight to improve
vehicle performance. In the
case of brake rotors, lighter is better
for a vehicle's acceleration, reliable
stopping, and even gas mileage. Orbis
Brakes Inc. licensed a NASA-patented
technology to accomplish that and
more. This revolutionary brake disc
design is at least 42 percent lighter
than conventional cast iron rotors,
with
performance
comparable
to
much more expensive carbon-ceramic
brakes.
Spinoff is NASA's annual publication featuring
successfully commercialized NASA technology. This
commercialization has contributed to the development
of products and services in the fields of health and
medicine, consumer goods, transportation, public safety,
computer technology, and environmental resources.
NASA's Invention Puts a New Spin on Automotive Brake Rotors
An innovative way to design a better automobile disc brake that's much lighter and
drastically improves the braking performance.
The periodic wave design of the Orbis Brakes NextWave
disc brake reduces the overall weight by about
40 percent while increasing surface area and incorporating
more efficient cooling to prevent overheating.
The design also reduces the release of brake pad
particulate matter into the environment. (Image: Orbis
Brakes Inc.)
During the pandemic shutdown,
Jonathan Lee, Structural Materials Engineer
at NASA's Marshall Space Flight
Center in Huntsville, AL, got to thinking
about disc brakes. His skills as a mechanical
designer backed with material science
training are usually focused on his
dual roles as the structural materials engineer
for the Space Launch System and
a microgravity material scientist for the
space station. Interested in supporting
NASA's other mission to advance technology
to improve life on Earth, he was
looking for an innovative way to design a
better automobile disc brake.
" NASA's willingness to help companies
be more successful, using all of
their expertise and the goodwill that extends,
is really amazing, " said Chance
Claxton, co-CEO of Santa Rosa, CAbased
Orbis Brakes.
Reducing the mass of its wheels means
a vehicle will use less energy to brake and
accelerate. Conventional brake discs are
heavy because they consist of two metal
plates cooled by air circulating between
them. The design is inefficient because
it's the outside surfaces that are heated by
friction with the brake pads, but the air
cooling takes place on the inside surfaces,
where the plates face each other. Lee
wanted to directly cool the hot surfaces
instead, allowing one of the heavy discs to
be eliminated from each of a vehicle's
Tech Briefs, May 2024
four rotors. His design proved to have additional
benefits as well.
He started with a single disc with a series
of small fins around the central hub.
As they spin, these draw in air and push
it across the surface of the disc, where
the brake pads make contact, cooling
the rotor, as well as the brake pads and
calipers. He then added several long depressions
around the braking surfaces,
radiating from the center to create the
regular, periodic pattern that gives the
new Orbis technology its PeriodicWave
brand name.
The spinning fins and the centrifugal
force of the wheel push air into the depressions,
causing a turbulent airflow
that draws away heat. " When the air
flings out, it goes across the brake caliper
and cools it - no conventional rotor
is capable of doing something crazy like
that. It's huge, " said Lee.
These trenches in the braking surfaces
also increase the available surface for air
cooling by more than 30 percent and
further reduce the weight of the disc.
And they increase friction in the same
way that scoring concrete makes steps
safer to walk on - the brake pads are
less likely to slip, which makes braking
more reliable.
The troughs draw away more than
just heat, too. Water and road debris
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Early adopters of the Orbis Brakes NextWave
disc brake for high-performance cars include the
personal vehicles of race car drivers who provide
the company feedback about performance. The
input will inform the design of future brakes for
electric cars, gas combustion-engine vehicles,
and everyday drivers. (Image: Orbis Brakes Inc.)
getting between the pad and rotor are
equally problematic, so the trenches
provide a place for the air vortex to
push any substance out of the way. A
small hole machined at the end of each
one creates an opening through which
unwanted material can escape. " And it
also just looks cool, " said Lee.
A second periodic wave is cut along
the outer edge of the disc. By replacing
the conventional circular design with an
undulating pattern, the new rotor has
still more surface area that will come
into contact with the cool air flowing
over it. This additional heat dissipation
will occur no matter which periodic wave
pattern is used, making it possible to create
funky designs and add personality to
what is usually a boring car part.
Finally, a thin layer of black coating
applied to surfaces that don't come into
contact with the brake pads, like the inside
of the troughs, can help the rotor
to radiate additional heat. This unique
three-part cooling system - convection
powered by airflow, conduction of heat
across the metal rotor, and radiation
37
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Tech Briefs Magazine - May 2024

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