CEO Cognizant Engineering Organization 
CFD computational fluid dynamics 
CH Cryptographic Hash 
cm Centimeter(s) 
CNC Computerized Numerical Control 
CoC Certificate of Conformance 
Comp Comparative 
CoV Coefficient of Variation 
DED Directed Energy Deposition 
DMA Dynamic Mechanical Analysis 
DOE Design of Experiment 
DOT Department of Transportation 
DPD Digital Product Definition 


DV Design Value 
EB-PBF Electron Beam Powder Bed Fusion 
EFCP Equipment and Facility Control Plan 
EIDP End Item Data Package 
FAA Federal Aviation Administration 
FEA finite element analysis 
FFRDC Federally Funded Research and Development Center 
FH Full Height 
FMEA Failure Modes and Effects Analysis 
GSE Ground Support Equipment 
HCF High Cycle Fatigue 
HDT Heat Deflection Temperature 
HIP Hot Isostatic Pressing 
in Inch(es) 
ISS International Space Station 
JSC Johnson Space Center 
L-PBF Laser Powder Bed Fusion 
LCF Low Cycle Fatigue 
M&P Materials and Processes 
MIUL Material Identification and Usage List 
MMPDS Metallic Materials Properties Development and Standardization 
MPS Material Property Suite 
MRB Material Review Board 
MSFC Marshall Space Flight Center 
MUA Material Usage Agreement 
NASA National Aeronautics and Space Administration 
NDE Nondestructive Evaluation 
NPD NASA Policy Directive 
NPR NASA Procedural Requirement 
NRRS NASA Records Retention Schedules 
NURBS Non-uniform Rational Basis Spline 
Opt Optimization 
PBF Powder Bed Fusion 
PCRD Process Control Reference Distribution 
PEEK polyether ether ketone 
PPP Part Production Plan 
Prod Production 
PSD Particle Size Distribution 
QMP Qualified Material Process 
QMS Quality Management System 
QPP Qualified Part Process 
Qual Qualification 
RFCB Responsible Fracture Control Board 
SI Système Internationale or metric system of measurement 


SLA Stereolithography 
SPC Statistical Process Control 
SPEC Specification 
STD Standard 
STL Standard Tessellation Language 
Sub Subsequent 
Tg glass transition temperature 
UTS Ultimate Tensile Strength 
UV Ultraviolet 
 YS Yield Strength 

3.2 Definitions 

Additive Manufacturing (AM):  Process of joining materials to make parts from three-
dimensional model data, usually layer upon layer, as opposed to subtractive manufacturing and 
formative manufacturing methodologies. Adj., additively manufactured. 

Additive Manufacturing Control Plan (AMCP):  Document describing the means of 
conformance, the method of implementation, and the tailoring rationale for each requirement in 
this NASA Technical Standard. 

Additive Manufacturing Part/Preform:  Any part using an AM process to produce some 
or all of the part material volume. For the purposes of this NASA Technical Standard, “part” and 
“preform” can be used interchangeably. Note:  A qualified part process may include multiple 
parts in a build. 

Additive Manufacturing Part Producer:  The entity using the AM process to produce a 
part. 

Additive Manufacturing Readiness Review (AMRR):  An integrated engineering review 
of the maturity of all manufacturing controls for an AM part to confirm that all necessary process 
controls and production engineering are in place to produce a part that fully and reliably meets 
the certified design state. At a minimum, the AMRR team includes individuals cognizant of the 
part from the disciplines of design, structural assessment, materials and processes, AM 
production, and safety and mission assurance. A successful, documented AMRR demarcates the 
production process of the part becoming a QPP. 

Batch:  Feedstock that can be composed of used material, virgin material, or a mixture of 
the two. 

Build/Build Cycle:  A single, complete operation of the AM process to create objects. 
Multiple objects are commonly created consecutively or concurrently during a build. 


Build Area:  The area in the build plane where the build process is controlled and 
qualified to a QMP per this NASA Technical Standard. The build area may be defined smaller 
than the full reach of the energy source or print head if needed to maintain the quality level of the 
build process. 

Build File:  A machine-readable file that requires no further changes to execute the AM 
fabrication process. 

Build Interruption:  An interruption of the programmed build sequence that deviates from 
the approved fixed process used to produce AM builds layer by layer. Build interruptions may be 
planned or unplanned. 

Build Lot:  All objects created during a single build operation. This can include multiple 
objects created consecutively or concurrently during the build. 

Build Plane:  Plane in which the build process takes place (i.e., the plane normal to the 
direction of material addition). For L-PBF, vat polymerization, and fused deposition modeling, 
the build plane is commonly fixed and the build platform is incrementally lowered to create the 
build. 

Build Platform:  Solid material base upon which parts are built. 

Build Record:  Any record of the outcome of a production process, including but not 
limited to those listed in the production engineering record, shop traveler, work authorization 
order, etc. 

Candidate Material Process:  A set of machine parameters, feedstock, and post-
processing specifications that constitutes a material process prior to its being registered to an 
MPS, at which point it becomes a QMP. 

Candidate Part Process:  A collection of all necessary content required to consistently and 
reliably produce an AM part compliant with the certified design state. This content includes but 
is not limited to an approved PPP, a QMP, preproduction article evaluation results, as well as all 
drawings, models, production engineering controls, parameter settings, etc., that are involved in 
the definition and production of the part. 

Catastrophic Hazard:  (1) A condition that could result in a mishap causing fatal injury to 
personnel and/or loss of one or more major elements of the flight vehicle or ground facility, or 
(2) a condition that may cause death or permanently disabling injury, major system or facility 
destruction on the ground, or loss of crew, major systems, or vehicle during the mission.  (See 
NPR 8715.3D, NASA General Safety Program Requirements.) 

Certified Design State:  A complete, stable design state that has been reviewed and 
verified as meeting all levied requirements to safely and reliably complete the intended mission. 


Certificate of Conformance (CoC):  A document signed by the supplier to affirm the product 
has met the requirements of the relevant specification(s), contract(s), and any other applicable 
regulations. 

Configuration Management:  Process for establishing and maintaining consistency of a 
product's functional and physical characteristics, evaluating and authorizing any changes to those 
characteristics, and recording and documenting the characteristics and any changes to them to 
verify compliance with the product's configuration requirements throughout its life. 

Critical Hazard:  A condition that may cause severe injury or occupational illness, or 
major property damage to facilities, systems, or flight hardware. (See NPR 8715.3D, NASA 
General Safety Program Requirements.. 

Cognizant Engineering Organization:  The organization responsible for 
establishing/maintaining the certified design state of the AM hardware and delivering AM 
hardware compliant with all levied requirements. The CEO will typically be a supplier to NASA, 
a subcontractor, or NASA. 

Containment, Primary:  An impermeable, chemically compatible tank, vessel, pipe, 
transport vessel, or equipment intended to serve as the primary container for, or for the transfer 
of, a material. 

Containment, Secondary:  An impermeable, chemically compatible tank, vessel, pipe, 
transport vessel, or equipment intended to serve as containment in the event of failure of the 
primary containment. 

Continuous Production Build:  Any build cycle within a continuous series, on the same 
machine, to the same or equivalent QMP, where each build and the AM machine is monitored 
and tracked in accordance with all SPC requirements of section 4.11 in this NASA Technical 
Standard. Continuous production builds have reduced witness sampling requirements; they rely 
on an integrated performance history of prior and subsequent builds and periodic SPC evaluation 
builds (same sample set as a subsequent [Sub]-QMP), to substantiate process control rationale. A 
series of continuous production builds may include a variety of builds for different parts. 

Customized Material Process:  Any candidate material process requiring specific controls 
or unique witness testing to achieve and/or demonstrate particular material performance 
characteristics. 

Design Value:  Material properties that are established from test data on a statistical basis 
and represent the finished part properties. These values are typically based on material 
allowables and adjusted, using building block tests as necessary, to account for the range of part-
specific features and actual conditions. Design values are used in analysis to compute structural 
design margin (e.g., margin of safety). (See also Material Allowable.) 


Digital Product Definition:  The finalized digital model encompassing all relevant 
drawings and process-specific information to generate a build file. 

Digital Thread:  The virtual medium in which data are stored and subsequently 
referenced through a part’s life cycle. This configuration-managed infrastructure contains and 
fingerprints the digital references for a part from foundational process controls through part 
production controls. 

Directed Energy Deposition:  AM process in which focused thermal energy is used to 
fuse materials by melting as they are being deposited. 

Equipment and Facility Control Plan:  Document that controls the AM equipment, 
associated facilities, and training of personnel involved with producing AM hardware. 

Equivalent QMP:  QMPs are considered equivalent if they meet the Subsequent-QMP 
commonality criteria as stated in section 5.5.1 of this NASA Technical Standard. 

Fatigue Limit:  A cyclic stress or strain range below which fatigue initiation failures are 
unlikely at a defined number of cycles based on fatigue testing. The fatigue limit is commonly 
defined at a pragmatic cycle count appropriate for the hardware, often 107 or 108 cycles. For the 
context of this NASA Technical Standard, a fatigue limit is defined to be ≥107 cycles. At this 
time, AM materials are not considered to have an endurance limit (a cyclic stress level below 
which fatigue life is infinite). 

Heat:  A material that, in the case of batch melting, is cast at the same time from the same 
furnace and is identified with the same heat number. 

Independent Build:  Any AM build cycle that is not part of a continuous production build 
series. Independent builds have additional witness specimen requirements that improve the 
ability to evaluate the quality of the build independent of the results of prior or subsequent builds 
from the AM machine. 

Influence Factors:  Any factor that has the capacity to alter the baseline performance of 
the material (i.e., the material allowable). For AM materials, influence factors may be 
fundamentally unique to the AM process (e.g., the unique impact of down-facing surfaces, local 
feature-driven anisotropy, or even part-specific geometric features). Other influence factors 
include environment (e.g., temperature, humidity) and surface conditions. 

Key Process Variables:  Elements of the AM process (e.g., build plate configuration, 
build layout, energy level, layer thickness, interpass temperature, melt pool environment, etc.) 
that, if changed, could affect physical, mechanical, metallurgical, dimensional, chemical, or 
performance characteristics. 


Material Allowable:  Material values that are determined from test data of the bulk 
material on a statistical basis. Allowable development approaches are established via industry 
standards (e.g., Metallic Materials Properties Development and Standardization (MMPDS) or 
company-specific methodology) and are based on testing conducted using accepted industry or 
company standards. Material allowables form the basis of design values. See also Design Value.) 

Material Property Suite (MPS):  A maintained collection of AM material property 
information specific to a material and condition that includes material test data, material 
allowables and associated design values, and criteria needed to implement and maintain SPC for 
the AM process. 

Material Property Suite, Lot-Mature:  An MPS that contains data from a minimum of five 
(5) unique feedstock lots and ten (10) build cycles and heat treat lots with a nominally balanced 
distribution across lot data used for all material allowables or design values that require bounding 
with statistical significance. Properties using a typical basis may be considered lot-mature with 
fewer lots. A lot-mature MPS has sufficient variability incorporated to allow the use of design 
values to be applied to parts of all classes built with feedstock lots equivalently controlled by an 
applicable, registered QMP. See section 6.5 and the definition for lot-provisional MPS in this 
NASA Technical Standard. 

Material Property Suite, Lot-Provisional:  An MPS that contains data from fewer than 
five (5) unique feedstock lots and ten (10) build and heat treat lots and/or does not demonstrate 
the nominally balanced distribution across a sufficient number of lots of data to be considered a 
lot-mature MPS. A provisional MPS has restrictions on use as required in section 6.5. See the 
definition for lot-mature MPS in this NASA Technical Standard. 

Material Usage Agreement:  The MUA process is NASA M&P best practice described by 
NASA-STD-6016, Standard Materials and Processes Requirements for Spacecraft, that enables 
acceptance of materials and material processes that do not meet the requirements of NASA-STD-
6016 and this NASA Technical Standard but, through the MUA review process, are determined 
to be acceptable. The MUA process also provides the benefit of satisfactorily resolving design 
nonconformances at the engineering level as opposed to the program level. The purpose of the 
MUA process is to justify the acceptance of specific material or material process design 
nonconformances, not the acceptance of a nonconforming product. 

Mission:  A major activity required to accomplish an Agency goal or to effectively 
pursue a scientific, technological, or engineering opportunity directly related to an Agency goal. 
Mission needs are independent of any particular system or technological solution. 

Mission Critical:  Item or function that must retain its operational capability to assure no 
mission failure (i.e., for mission success. Mission-critical items or processes may be identified 
using system design and reliability analyses (e.g., failure modes and effects analysis [FMEA]). 


Nonconformance:  The state or situation of not fulfilling a requirement. A nonconforming 
product, process, software, or material does not meet manufacturing specifications/design, 
composition, or contractual requirements. Examples include but are not limited to failures, 
discrepancies, defects, anomalies, and malfunctions. 

Post-Build Microstructure:  Microstructure specimens built after the part is complete, 
required for DED only. 

Post-Build Tensile:  Tensile specimens built after the part is complete, required for DED 
only. 

Part Agnostic:  A description of documentation, processes, data, etc., that is not specific 
to a single part and/or configuration. 

Part Design:  A collection of attributes that describe the fit, form, and function of a part, 
including its environmental context. 

Part Material Specifications:  A defined set of characteristics and requirements for the 
final material condition of a finished part (material requirements, including chemistry, may be 
different from the feedstock to finished part). 

Part Production Plan:  Document that defines the full intent for the design, production, 
and use of the AM part, including unique controls.  The purpose of the PPP is to ensure 
engineering integration across disciplines and provide insight into risks associated with the part 
and its manufacture. 

Powder Bed Fusion (PBF):  An AM process that uses a high-energy source to selectively 
fuse, layer by layer, portions of a powder bed. 

Powder Lot (also blended powder lot):  A quantity of powder supplied by a certified 
powder producer that was manufactured by the same process and equipment and blended 
simultaneously. The blended powder lot may contain multiple heats of powder when all heats 
independently meet the powder specification. 

Process Control Reference Distribution (PCRD):  A statistical model representing the 
nominal performance of a material property used for monitoring process control. A PCRD is 
developed for material produced to an approved QMP and tested with a consistent specimen 
geometry, size, orientation, and test procedure. A PCRD is used to define the acceptance criteria 
applied to selected witness tests for an AM build cycle; the data used to develop the statistical 
PCRD model are typically the result of nominal witness tests and other data generated with the 
same consistent specimen geometry and test procedure. 


Production Engineering Record:  A revision-controlled document or electronic record 
that defines and records the sequence of all major operations and their outcomes when producing 
a part. 

Protoflight:  The protoflight unit is intended for flight on which a partial or complete 
protoflight qualification test campaign is performed before flight (as opposed to an acceptance 
test campaign). See also NPR 8705.4, Risk Classification for NASA Payloads. 

Quality Management System:  A formalized enterprise-wide system of controls used to 
consistently realize processes and products that meet requirements, generate evidence of process 
and product conformance, preserve the integrity of conforming product through delivery to the 
customer, and provide for design and process corrections and improvements. 

Qualified Material Process (QMP):  The foundational AM process control of feedstock, 
machine process controls, and post-processes that enable parts to be built with a consistent 
process of verified material quality. The use of a QMP provides the rationale for the assumed 
material capability of a part and provides quantifiable metrics to monitor the quality of the 
material process over time. 

Qualified Material Process, Subsequent (Sub-QMP):  A qualified material process that 
has the same feedstock specification and controls, AM build processes (e.g., the same key 
process variables), and post-processing as an existing QMP. The commonality to the existing 
process allows for reduced testing to establish a qualified process. 

Qualified Part Process (QPP):  The full content of the candidate part process following 
completion of the AMRR process and approval by the CEO. The entirety of the QPP content is 
configuration controlled by the QMS such that any changes to the contents of