Page 26 - Plastics News January 2021

FeAtures

Busting Myths: How Additive Polymers Affect Builds

John Nanry

Some ideas that were accurate ten years ago are completely off base now so are the perceptions in the early
days of AM, the process is no longer relegated to prototyping. And on needs to update

ith additive manufacturing (AM) becoming more many brittle materials including epoxies and composites.
Wprevalent in manufacturing, even in high-production For ductile materials, RPU 70 can compete with
environments, many traditional manufacturers are polyurethanes and polycarbonates, and EPU 40/41 can
considering turning toward it for certain applications. compete with hyperelastics like rubbers and elastomers.
However, leaping into an entirely new field of manufacturing
can be daunting, and it helps to have guidance from people
with experience.
“A lot of myths have cropped up around AM,” says John
Nanry, Co-Founder and Chief Fulfillment Officer at Fast
Radius. “Some ideas that were accurate ten years ago are
completely off base now.” Deciding if AM is right for your
application means busting these myths and basing your
decision on the current state of AM.

Often enough, AM materials can outperform legacy ones.
An elastomeric lattice structure 3D printed with EPU 41.
This design can compete with hyperelastics like rubbers
and elastomers.
Even older AM plastics have found success in full-scale
production. In aerospace, for example, the properties of
the polyetherimide ULTEM has earned it FAA certifications
for non-critical components. The material is commonly
The above chart shows the mechanical properties of three used in Fused Deposition Modeling (FDM), and its strength-
common additive materials and lists the legacy materials to-weight ratio resembles that of some aluminum alloys,
they might replace. which makes it ideal for replacing certain heavier metals
and weaker plastics.
In the world of manufacturing, a part is only as good as
the material it is made of, and the perception of AM parts Of course, the properties of an AM part depend not just
as weak or porous often leads manufacturers to see it as a on materials, but also on technology. “While it is true that
hobbyist pursuit. While this perception was well-founded early layer-by-layer 3D printing technology often produced
in the early days of AM, the process is no longer relegated parts that lacked consistent directional density,” Nanry
to prototyping. Many modern additive materials have says, “newer methods like vat polymerization and powder
isotropic or near-isotropic mechanical properties, making bed fusion (PBF) produce much denser and more uniform
them similar in structure to injection-molded plastics. parts.” Modern technologies have reduced – and in some
cases even eliminated – the issues that led to failures in the
Today, many AM materials can compete directly with
traditional polymers. For example, CE 221 can replace past, improving the consistency and reliability of AM parts.

Plastics News Januar y 2021 26