synthesis” rather than 3-D printing, a
way of alluding to its novel chemistry.
Adding credibility to DeSimone’s
claim that 3-D printing is finally ready
to mass-manufacture customized parts
is Carbon’s growing list of paying customers. “The volume and speed we can
achieve with Carbon’s pioneering digital
light synthesis is unprecedented,” says
Paul Gaudio, the global creative director
of Adidas. “It’s almost magical.” Adidas
tried other 3-D printers as it sought to
make customized shoes for the mass
market, but none of them could operate
at large scale. Now it will use Carbon’s
technology to manufacture elastomer
midsoles for athletic shoes, starting
with 5,000 pairs this fall and winter.
The company hopes to print millions of
shoes, including custom-tailored models, by 2021. Other customers are taking advantage of Carbon’s technology
to print parts for electric motorcycles,
server farms, and cooling systems, all of
which have been difficult or impossible
to make with other methods.
Before he founded Carbon in 2013,
DeSimone spent more than 20 years
as a polymer chemist at the University
of North Carolina. In 2012, as 3-D printing was becoming popular with hackers using desktop models, he received
a call from Alex Ermoshkin, a former
employee of his lab and of a drug delivery company DeSimone had started up
in the early 2000s. Ermoshkin came
to him with a business idea: would he
be interested in starting a company to
build cheaper 3-D printers?
DeSimone, who had some experi-
ence with the technology, was intrigued.
He suggested that Ermoshkin do a pat-
ent search to see what was missing
in the field. Ermoshkin found many
descriptions of ways to print three-
dimensional objects one layer at a time, some using UV light to link up chemical
building blocks and harden them to form polymers. Stereolithography is one of
the original 3-D-printing methods, but it has always been limited by the properties
of such UV-curable plastics, which have not included durability or flexibility. Also,
resulting products formed in layers tended to be weak. Stereolithography is useful
for making prototypes, but not for final parts. What’s more, the printers were very
slow, taking hours or even days to make large objects.
The two began to think about how to print without stopping. They were inspired,
DeSimone says, by the image of the T-1000 humanoid robot rising up out of a pool
of metallic liquid to stand on two feet in the 1991 movie Terminator 2: Judgment
Day. In the system that DeSimone and Ermoshkin imagined, light patterns would be
projected into the bath, like images on a movie screen, as the printer arm moved
up. As the light hardened the material, layers would form continuously.
Among the tricky challenges the team had to solve was how to keep objects
from sticking to the bottom of the bath. DeSimone came up with the solution: an
oxygen-permeable window, which takes advantage of the fact that these types of
UV-triggered reactions are stopped by oxygen. It’s a small detail, but a critical one.
Carbon’s vice president of materials, Jason Rolland, says the company has
focused on overcoming the limitations of
UV-curable polymers, developing blends
that offer a wide range of properties. The
system can now print with 12 classes of
materials—some durable, some stretchy or
squishy, some able to bear heavy weights.
One, a cyanate ester that can withstand
temperatures up to 220 °C, is suitable for
making automotive and aerospace parts.
Another class, elastomers, includes the
squishy materials Adidas is using. DeSimone
foresees “an app store for resins” from
which the company’s customers can order
to print what they need.
Carbon worked with Adidas on 150 different iterations of the elastomer in its new
shoe, which uses a printed midsole with a lattice structure. The structure’s mechanical properties can be tailored by changing the pattern of the lattice’s holes and
struts, bringing personalization to a mass scale.
In Carbon’s lobby, a large display screen shows the operating status of all its
printers, both on site and with customers. The company sells the devices on a
subscription model and then works with customers to select the right materials
and designs. Every six weeks or so, Carbon sends out software updates based
on what it is seeing in the field—a tactic inspired by Tesla, the former employer of
Carbon’s VP of engineering, Craig Carlson. Carbon is now designing machine-learning software to help generate the optimal printing design and parameters for any
given product. “We want to see the problems before we print,” DeSimone says.