Tech Briefs Magazine - December 2022 - 11

high-value manufacturing throughout
the United Kingdom. The MTC is based
in the historic English industrial city of
Coventry, but its focus is solely on the
future. That is why the team has committed
significant human and technical
resources to its National Centre for Additive
Manufacturing (NCAM).
" Adopting AM is not just about installing
new equipment. Our clients are also
seeking help with implementing the digital
infrastructure that supports AM factory
operations, " said Holloway. " Along
with enterprise software and data connectivity,
we're exploring how to embed
simulation within their systems as well. "
The NCAM's Digital Reconfigurable
Additive Manufacturing for Aerospace
(DRAMA) project provides a valuable
venue for this exploration. Developed
in concert with numerous manufacturers,
the DRAMA initiative includes the
new powder bed fusion AM facility mentioned
previously. With that mini factory
as DRAMA's stage, Holloway and his fellow
simulation specialists play important
roles in making its production of AM
aerospace components a success.
Making Soft Material Add Up
to Solid Objects
What makes a manufacturing process
" additive " , and why are so many industries
exploring AM methods? In the
broadest sense, an additive process is
one where objects are created by adding
material layer by layer, rather than
removing it or molding it. A reductive
or subtractive process for producing a
part may, for example, begin with a solid
block of metal that is then cut, drilled,
and ground into shape. An additive
method for making the same part, by
contrast, begins with empty space. Loose
or soft material is then added to that
space (under carefully controlled conditions)
until it forms the desired shape.
That pliable material must then be solidified
into a durable finished part.
Different materials demand different
methods for generating and solidifying
additive forms. For example, common
3D printers sold to consumers produce
objects by unspooling warm, plastic filament,
which bonds to itself and becomes
harder as it cools. By contrast, the metal
powder bed fusion process begins with,
as its name suggests, a powdered metal
which is then melted by applied heat
and re-solidified when it cools. A part
produced via the metal powder bed fusion
process can be seen in Figure 1.
Tech Briefs, December 2022
Figure 1. An example of a part produced through the metal powder bed fusion process. (Image:
COMSOL Inc.)
How Heat and Humidity Affect
Metal Powder Bed Fusion
" The market opportunities for AM
methods have been understood for a
long time, but there have been many
obstacles to large-scale adoption, " Holloway
said. " Some of these obstacles
can be overcome during the design
phase of products and AM facilities.
Other issues, such as the impact of
environmental conditions on AM production,
must be addressed while the
facility is operating. "
For instance, maintaining careful control
of heat and humidity is an essential
task for the DRAMA team. " The metal
powder used for the powder bed fusion
process (Figure 2) is highly sensitive
to external conditions, " said Holloway.
" This means it can begin to oxidize and
pick up ambient moisture even while it
sits in storage, and those processes will
continue as it moves through the facility.
Exposure to heat and moisture will
change how it flows, how it melts, how
it picks up an electric charge, and how
Figure 2. A microscopic close-up of powdered metal grains, as used for powder bed fusion.
(Image: COMSOL Inc.)
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