Effects of Defects within Metal Additive Manufacturing Systems
PROGRAM: Cross Platform Systems Development (CPSD) Research & Development
Develop and demonstrate an empirical database of allowable process defects and
variations to aid quality control and nondestructive evaluation of additively
manufactured metal components.
Additive manufacturing (AM) systems, especially metal AM, bring revolutionary
capabilities, but suffer from a lack of understanding of the defects that exist
within the components. Developing a database of the effects of defects, such
as mechanical performance and material properties within an additively
manufactured component, will provide a means of certifying these components at
a more rapid rate without having to perform traditional “brute force” type
methods of destructively testing large numbers of components. Current
commercial efforts to quantify the effects of defects on additively
manufactured components focus on this sort of brute force testing, with an
emphasis on expensive micro computed-tomography imaging and extensive
destructive testing in order to qualify a printed component. The database
developed during this project will provide a faster response manufacturing
capability to the Navy with increased flexibility.
The Naval fleet suffers from long lead times to obtain replacements for broken,
worn, or otherwise failed parts. AM technology has the potential to reduce
supply chain issues and enable new designs through unique layer-by-layer
fabrication capabilities. The significant advance in AM technology recently
has been demonstrated in the private sector – the most visible recent example
being General Electric’s LEAP Turbine Engine fuel nozzle, where an assembly of
dozens of components was reduced to a single printed part and qualified by extensive
destructive testing, but no existing commercial database is available as a
To enable the Navy to harness metallic AM capabilities for end-use items, the
ability to identify the effects of defects within additively manufactured
components is critical. Parts manufactured by metal AM typically suffer from a
combination of several defect types that can inhibit the functional performance
of a part, and reduce confidence in designing parts for this manufacturing
method. A system for quantifying the effect of defects on printed parts is
desired. As defined by MIL-STD 2035A, such defects can be porosity,
inclusions, large-scale voids, and chemical inconsistencies, and all of these
can affect the mechanical performance and material properties of a printed
The desired system would quantify the effect of these various defects,
establish an allowable defect frequency for printed parts, and be applicable
across multiple material types and AM systems, especially laser and electron
beam powder bed fusion as well as directed energy deposition.
The desired system’s performance goals would be to:
(1) Provide a method for nondestructively locating and classifying defects
within a printed part quickly, with minimum technician support required, and
with a minimum of specialized equipment (without having to test every component
using microcomputer tomography (Micro CT);
(2) Quantify the effects of multiple defect types on the mechanical performance
and material properties of printed parts. Defect types of interest are Small
voids (particularly due to lack of fusion or vector spacing/path direction);
Inclusions (powder contamination or powder size inconsistency leading to
unfused material); Large voids (powder short-feeds, powder collapse, or other print
errors); Chemical inconsistencies (powder contamination, carbide formation,
(3) Provide a database of permissible defect sizes, distributions, densities,
or other allowable metrics for quality control (QC) pass/fail testing in multiple
materials: 316SS, Commercially Pure (Grade 2) Titanium, IN625, IN718, and
(4) Provide an end-to-end system demonstration, including a NAVSEA-selected
part printed in one of the above materials, to demonstrate successful
application of the developed testing method and material database.
Emphasis should be placed on a solution(s) that successfully achieve(s) the
listed objectives, while minimizing cost/complexity (not relying solely on
processes like microcomputer tomography (CT), etc.), especially those that do
not require extensive mechanical test specimens to be printed alongside the
final part, and those that do not require highly specialized testing for the
final part. Advanced test methods are welcome, but attention should be paid to
testing and calibration costs. Development of the material database is
expected to include complex and highly specialized testing – the goal of the
project should be to build a database so that those same tests are not required
on every part after the database is developed.
By providing a database to reduce cost and time to qualify an additively
manufactured metal component, maintenance costs can be substantially reduced.
Increased confidence and understanding of mechanical performance from parts
produced by metal additive manufacturing, candidate parts can be more quickly
selected. Improved quality control means that replacement parts and tools can
reach the fleet sooner, increasing system availability, reducing maintenance
and downtime costs, and improving mission and warfighter flexibility by 20%.
I: Develop a concept method to determine the effect of defects on printed
mechanical test specimens in one material, and use the data collected by
executing their planned experiments to develop the framework for the larger
material database. Develop a program plan and structure to conduct print
testing using their method on multiple materials in Phase II. The Phase I
Option, if awarded, will include the initial design specifications and
capabilities description to build a prototype in Phase II. Develop a Phase II
II: Based on the Phase I results and the Phase II Statement of Work (SOW),
design, develop, and deliver a prototype framework database. In Phase II,
testing to collect the necessary data to develop the final mechanical database
in multiple materials will be performed, and the database and set of design
allowable for each material will be assembled. The project team will also
develop a plan to demonstrate the complete system on a NAVSEA-provided part in
III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology to
Navy use, especially in the regional maintenance centers and warfare centers.
Phase III serves as a complete, end-to-end systems demonstration for the method
developed in Phases I and II. Using a part(s) provided by NAVSEA, the team
will print and qualify the part(s) using their process, and provide a report on
the results of their testing.
A reliable, fast, and low-cost empirical database for QC in additively
manufactured metal components is applicable in multiple industries, especially
the aerospace and automotive sectors, where qualification efforts to date have
been primarily brute force efforts. By providing a database by which printed parts
can be quickly confirmed as meeting some minimum set of operational criteria,
significant cost reduction in metal AM is possible. Part cost reduction is
always a goal of manufacturers, and would make the system developed under this
SBIR/STTR attractive to private-sector organizations.
“NONDESTRUCTIVE TESTING ACCEPTANCE CRITERIA,” MIL-STD-2035A (SH) 15 MAY 1995, http://everyspec.com/MIL-STD/MIL-STD-2000-2999/MIL-STD-2035A_6636/
Bauereiß, A., Scharowsky, T., & Körner, C. “Defect generation and
propagation mechanism during additive manufacturing by selective beam melting.”
Journal of Materials Processing Technology, 2014, 214(11), 2522-2528. http://www.sciencedirect.com/science/article/pii/S0924013614001691
Gong, H., Rafi, K., Gu, H., Starr, T., & Stucker, B. “Analysis of defect
generation in Ti–6Al–4V parts made using powder bed fusion additive
manufacturing processes.” Additive Manufacturing, 2014, 1, 87-98. http://www.sciencedirect.com/science/article/pii/S2214860414000074
Metal Additive Manufacturing; Quality Control for Additive Manufacturing;
Effect of Defects in Additive Manufacturing; Material Database; Material
Performance in Additive Manufacturing; Part Qualification in Additive
** TOPIC NOTICE **
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