Engineering Inc - July/August 2018 - 20

At the Consumer Electronics Show in Las Vegas in January
2018, 3D printers were a common attraction, but manufacturer
Aleph Objects, Inc., caught participants' attention by using 150 3D
printers at its booth to build new 3D printers.
As futuristic as that may sound, Aleph Objects has been using 3D
printers to manufacture 3D printers since 2011.
While frequently touted as the "next big thing," in reality 3D
printing has been around for quite a while. The first 3D printer
was created in 1984, and the technology has gone mainstream in a
variety of industries, from food processing to fashion to jet engine
manufacturing. The process is also being incorporated into the
health care industry for its potential in human tissue repair and cancer research. By definition, 3D printing refers to processes in which
material is joined or solidified under computer control to create a
3D object, with material being added together, such as liquid molecules or powder grains being fused. Potential applications, however,
are endless.
Engineering is fertile ground for 3D printing. Firms are already
using 3D printers to create scale models, design unorthodox components, combine materials, test tolerances and build structures.
"I see almost endless potential for 3D-printed building components," says Enrico Dini, an Italian engineer and pioneer in largescale 3D printing. "There are huge opportunities in building components. Traditional processes can't match the levels of complexity
and accuracy that you can get with 3D printing."
BIGGER AND BETTER

Three-dimensional printing is also known as additive manufacturing, in that the printer works off a digital design to add successive
material layers in a sequential manner to create a desired object. For
engineers, the technology has developed in two key ways. First, the
types of materials that can be printed are constantly expanding and
include thermoplastic, metal, powder, ceramic, paper, photopolymer, liquid and concrete.
Not only that, says Thornton Tomasetti Principal Rob Otani,
"We can use 3D printers to change material properties. We can
make composites that we would not be able to make manually."
Printers have also gotten bigger. Most printers are as big as an
office printer, but companies are testing the limits of size. Dini has
designed a 3D printer that is 40 feet by 40 feet by 32 feet.
While there are numerous types of 3D printers, the two that have
had the biggest impact on the A/E/C industry are extrusion printers
and inkjet head and powder bed printers.
Extrusion printers dispense the material through a nozzle. Several
companies are marketing large extrusion printers that use gantry
systems to lay down a concrete bead that builds up to form the
walls of a structure. A Chinese construction firm 3D printed a

Thornton
Tomasetti 3D
printed Flotsam
and Jetsam,
two 30-foot
by 30-foot by
10-foot structures
printed out of
biodegradable
bamboo, for the
Design Miami
Festival in 2016.

small house in 24 hours using one of these printers, and a developer
announced plans to build a community of 1,000 3D-printed homes
in Russia.
With an inkjet head and powder bed printer, fine binder droplets
are sprinkled onto a thin layer of a powdered material, a roller compacts and binds the layer, more powder is applied and the process
repeats until the bound-together powder layers form the desired
object. Follow-up treatments can be applied to improve the material
strength.
"We have scaled up this process," says Dini. "Instead of using
powder, we use sand or aggregates or gravel, and instead of using
binder, we use cement."
In 2005, Dini used one of these printers to manufacture the
components for a small house in Italy. More recently, he printed the
components to build a concrete pedestrian bridge in Spain.
In the U.S., Thornton Tomasetti has been a pioneer in 3D-printing technology within the engineering industry. In 2016, the firm
engineered two 30-foot by 30-foot by 10-foot structures for the
Design Miami Festival. "We're working on one now in Nashville
that would have a 35- to 38-foot span," says Otani.
Other 3D-printing processes have made their way into construction for specialized applications. MX3D, a technology startup in

"Once the regulatory bodies come up with a way to
qualify and certify 3D-printed structures, there's no limit
to what we could see."
HEATHER REED
THORNTON TOMASETTI

ENGINEERING INC.

JULY / AUGUST 2018

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