Aerospace & Defense Technology - December 2022 - 5

ability to not only print exactly what's
desired without compromising on design,
but improved performance metrics provided
by complex internal passageways;
low-angle, support-free blading and tubing;
and " impossible " geometries not
previously imaginable.
AM in Commercial Aviation
An understandable abundance of
caution related to human flight has
resulted in a regulatory environment
that has slowed commercial aviation's
move towards adoption of AM to some
extent. Although a variety of 3D-printed
parts have been certified by major
players in that industry-GE aircraft
engine components are the best-known
example-this has involved many years
of proprietary development time and
considerable expense (FAA 14 CFR 21.1
permits airframe, engine, and propeller
manufacturers to make AM parts, with
exacting certification requirements).
However, last year's announcement
of an MMPDS (Metallic Materials Properties
Development & Standardization)
materials spec, for Alloy 718, an Inconel™,
is a step toward levelling the
field for aviation-related companies of
all sizes. MMPDS is an industry-based
source for design allowables recognized
by the FAA, DoD and NASA.
Inconel is the first of several materials
(aluminum and titanium are next)
being evaluated for use with 3D-printed
parts and repairs.
This, in turn, is increasing the value
of AM to commercial aviation for supply
chain " fixes, " i.e., when a casting shop
no-quotes a legacy part, or lead times for
a replacement are astronomical. LPBF
technology can help offset the high costs
of low-volume, direct-part replacement
of conventionally produced parts when
demand and long-term forecasting are
uncertain. This significantly impacts the
economics of future Maintenance, Repair
& Operations (MRO) projects.
3D-printed parts must provide inherent
value because they are 3D-printed.
For example, with complex gas turbine
combustor components with optimized
interior geometries-that will have limited
aftermarket availability or high
replacement cost-AM can enable a CM
to produce hardware for its customers
A cross-sectioned thrust chamber printed in GRCop-42, a copper/chromium/niobium alloy designed for
high-strength dispersion and high conductivity. The chamber walls contain internal channels for regenerative
cooling. This material was developed by NASA for use in regenerative rocket engines. It is shown here
as-printed (L) and polished (R).
Large 21-inch (535 mm) diameter stator ring featuring low angle blades and internal cooling channels. In
a jet turbine, the stator element contains blades or ports used to redirect the flow of fluid. Part shown
as-printed. This part was printed on a Velo3D Sapphire XC machine, which is capable of printing parts 600
mm in diameter and 550 mm in height.
on-demand, negating the high NPI (new
product introduction) tooling costs and
lead-times of other methods.
AM in Aerospace and Defense
On a faster pace than commercial aviation,
unmanned space flight, satellite
launch, hypersonics R&D, and drone
Aerospace & Defense Technology, December 2022
mobilityengineeringtech.com
production have been leaping ahead
with metal AM in the past few years.
Applications include monolithic, nozzle/combustion
chamber combinations
that consolidate large assemblies of parts
into one, as well as impellers, stators,
fuel tanks, pump housings, complex
tubing, and lightweight microturbines.
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Aerospace & Defense Technology - December 2022

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