ASTM F3187-16(2023)

Standard Guide for Directed Energy Deposition of Metals

SIGNIFICANCE AND USE
5.1 This guide applies to directed energy deposition (DED) systems and processes, including electron beam, laser beam, and arc plasma based systems, as well as applicable material systems.  
5.2 Directed energy deposition (DED) systems have the following general collection of characteristics: ability to process large build volumes (>1000 mm3), ability to process at relatively high deposition rates, use of articulated energy sources, efficient energy utilization (electron beam and arc plasma), strong energy coupling to feedstock (electron beam and arc plasma), feedstock delivered directly to the melt pool, ability to deposit directly onto existing components, and potential to change chemical composition within a build to produce functionally graded materials. Feedstock for DED is delivered to the melt pool in coordination with the energy source, and the deposition head (typically) indexes up from the build surface with each successive layer.  
5.3 Although DED systems can be used to apply a surface cladding, such use does not fit the current definition of AM. Cladding consists of applying a uniform buildup of material on a surface. To be considered AM, a computer aided design (CAD) file of the build features is converted into section cuts representing each layer of material to be deposited. The DED machine then builds up material, layer-by-layer, so material is only applied where required to produce a part, add a feature or make a repair.  
5.4 DED has the ability to produce relatively large parts requiring minimal tooling and relatively little secondary processing. In addition, DED processes can be used to produce components with composition gradients, or hybrid structures consisting of multiple materials having different compositions and structures. DED processes are also commonly used for component repair and feature addition.  
5.5 Fig. 1 gives a general guide as to the relative capabilities of the main DED processes compared to others currently used for meta...
SCOPE
1.1 Directed Energy Deposition (DED) is used for repair, rapid prototyping and low volume part fabrication. This document is intended to serve as a guide for defining the technology application space and limits, DED system set-up considerations, machine operation, process documentation, work practices, and available system and process monitoring technologies.  
1.2 DED is an additive manufacturing process in which focused thermal energy is used to fuse materials by melting as they are being deposited.  
1.3 DED Systems comprise multiple categories of machines using laser beam (LB), electron beam (EB), or arc plasma energy sources. Feedstock typically comprises either powder or wire. Deposition typically occurs either under inert gas (arc systems or laser) or in vacuum (EB systems). Although these are the predominant methods employed in practice, the use of other energy sources, feedstocks and atmospheres may also fall into this category.  
1.4 The values stated in SI units are to be regarded as standard. All units of measure included in this guide are accepted for use with the SI.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 14-Dec-2023
• ICS: 25.160.10 - Welding processes
• ICS: 77.020 - Production of metals
• Technical Committee: F42 - Additive Manufacturing Technologies
• Drafting Committee: F42.05 - Materials and Processes

Relations

• Replaces: ASTM F3187-16 - Standard Guide for Directed Energy Deposition of Metals
• Effective Date: 15-Dec-2023
• Refers: ASTM E1316-24 - Standard Terminology for <?Pub Dtl?>Nondestructive Examinations
• Effective Date: 01-Feb-2024
• Refers: ASTM E1316-23b - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Sep-2023
• Referred By: ASTM E3166-20e1 - Standard Guide for Nondestructive Examination of Metal Additively Manufactured Aerospace Parts After Build
• Effective Date: 15-Dec-2023
• Referred By: ASTM F3413-19e1 - Guide for Additive Manufacturing - Design - Directed Energy Deposition
• Effective Date: 15-Dec-2023

Overview

ASTM F3187-16(2023), Standard Guide for Directed Energy Deposition of Metals, provides comprehensive guidance for the implementation and use of directed energy deposition (DED) systems in metal additive manufacturing. Developed by ASTM International, this standard sets practical parameters for DED system set-up, operation, process documentation, and safety, focusing on processes that employ focused thermal energy-such as laser beam, electron beam, and arc plasma systems-to fuse materials by melting as they are being deposited.

Directed energy deposition is widely used for repair, rapid prototyping, and low-volume metal part fabrication. The guide seeks to clarify best practices, system limitations, terminology, and quality considerations across various DED technologies and feedstock options, including both wire and powder forms. The standard supports users in achieving reliable, repeatable, and high-quality additive manufacturing outcomes while adhering to established safety and quality protocols.

Key Topics

• DED Technology Fundamentals

  • Explains the principles of directed energy deposition as a form of additive manufacturing, where material is deposited layer-by-layer according to computer-aided design (CAD) models.
  • Covers the unique capability of DED to produce large build volumes, high deposition rates, and functionally graded materials.

• System Components

  • Identifies essential elements of a DED system, including heat sources (laser, electron beam, arc plasma), feedstock delivery methods (powder or wire), motion devices for precise control, and atmosphere management (inert gas or vacuum environments).
  • Provides guidance on deposition head design and integration for efficient energy and material delivery.

• Process Control and Documentation

  • Emphasizes the importance of rigorous process monitoring, machine calibration, and process documentation to ensure consistent output quality across projects.
  • Discusses key variables such as deposition rate, layer thickness, temperature control, and post-processing requirements.

• Safety, Health, and Environmental Practices

  • Highlights user responsibilities regarding system safety, operation in regulated environments, and implementation of quality management systems.
  • References associated standards for occupational health, fire safety, and safe handling of materials and equipment.

Applications

Directed Energy Deposition is a versatile additive manufacturing solution with a range of real-world applications:

• Component Repair:
  • Used extensively to restore, rebuild, or enhance worn or damaged metal components, minimizing downtime and material waste.
• Rapid Prototyping:
  • Enables fast, flexible production of prototype parts for testing and validation before full-scale manufacturing.
• Feature Addition and Customization:
  • Facilitates the addition of features or material gradients to existing structures, supporting advanced engineering applications and product customization.
• Hybrid and Functionally Graded Structures:
  • Supports the fabrication of parts with varying material compositions or multi-material integration within a single build, enhancing functional performance.
• Low-Volume Part Fabrication:
  • Well-suited for specialized, low-volume, or custom metal part production where traditional tooling would be cost-prohibitive.

Related Standards

ASTM F3187-16(2023) references and complements several other internationally recognized standards for additive manufacturing, quality control, safety, and materials testing:

• ASTM B214: Test Method for Sieve Analysis of Metal Powders
• ISO/ASTM 52900: Additive Manufacturing-General Principles-Terminology
• ISO/ASTM 52921: Standard Terminology for Additive Manufacturing-Coordinate Systems and Test Methodologies
• ISO 9001: Quality Management Systems-Requirements
• AWS A3.0/A3.0M: Standard Welding Terms and Definitions
• NFPA 484: Standard for Combustible Metals
• OSHA 29 CFR 1910: Occupational Safety and Health Standards

By aligning with these related standards, users of ASTM F3187-16(2023) can ensure compatibility, interoperability, and compliance within global additive manufacturing and industrial environments.

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Keywords: Directed energy deposition (DED), ASTM F3187, metal additive manufacturing, laser deposition, electron beam, arc plasma, powder feed, wire feed, process control, component repair, rapid prototyping, functionally graded materials, AM standards.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F3187 − 16 (Reapproved 2023)
Standard Guide for
Directed Energy Deposition of Metals
This standard is issued under the fixed designation F3187; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 The latest version of the specifications referenced below
1.1 Directed Energy Deposition (DED) is used for repair,
should be used, unless specifically referenced otherwise in the
rapid prototyping and low volume part fabrication. This
main document.
document is intended to serve as a guide for defining the
technology application space and limits, DED system set-up 2.2 ASTM Standards:
B214 Test Method for Sieve Analysis of Metal Powders
considerations, machine operation, process documentation,
C1145 Terminology of Advanced Ceramics
work practices, and available system and process monitoring
D6128 Test Method for Shear Testing of Bulk Solids Using
technologies.
the Jenike Shear Tester
1.2 DED is an additive manufacturing process in which
E11 Specification for Woven Wire Test Sieve Cloth and Test
focused thermal energy is used to fuse materials by melting as
Sieves
they are being deposited.
E1316 Terminology for Nondestructive Examinations
E1515 Test Method for Minimum Explosible Concentration
1.3 DED Systems comprise multiple categories of machines
of Combustible Dusts
using laser beam (LB), electron beam (EB), or arc plasma
F327 Practice for Sampling Gas Blow Down Systems and
energy sources. Feedstock typically comprises either powder
Components for Particulate Contamination by Automatic
or wire. Deposition typically occurs either under inert gas (arc
Particle Monitor Method
systems or laser) or in vacuum (EB systems). Although these
F2971 Practice for Reporting Data for Test Specimens Pre-
are the predominant methods employed in practice, the use of
pared by Additive Manufacturing
other energy sources, feedstocks and atmospheres may also fall
2.3 ISO/ASTM Standards:
into this category.
52900 Additive Manufacturing—General Principles—
1.4 The values stated in SI units are to be regarded as Terminology
standard. All units of measure included in this guide are 52921 Standard Terminology for Additive Manufacturing—
Coordinate Systems and Test Methodologies
accepted for use with the SI.
2.4 ASQ Standard
1.5 This standard does not purport to address all of the
ASQ C-1 Specification of General Requirement For A Qual-
safety concerns, if any, associated with its use. It is the
ity Program
responsibility of the user of this standard to establish appro-
2.5 AWS Standards:
priate safety, health, and environmental practices and deter-
A3.0/A3.0M Standard Welding Terms and Definitions
mine the applicability of regulatory limitations prior to use.
A5.01/A5.01M Procurement Guidelines for Consumables—
1.6 This international standard was developed in accor-
Welding and Allied Processes
dance with internationally recognized principles on standard-
A5.02/A5.02M Specification for Filler Metal—Standard
ization established in the Decision on Principles for the
Sizes Packaging and Physical Attributes
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
1 3
This guide is under the jurisdiction of ASTM Committee F42 on Additive Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
Manufacturing Technologies and is the direct responsibility of Subcommittee 4th Floor, New York, NY 10036, http://www.ansi.org.
F42.05 on Materials and Processes. Available from American Society for Quality, P.O. Box 3005, Milwaukee, WI
Current edition approved Dec. 15, 2023. Published January 2024. Originally 53201-3005.
approved in 2016. Last previous edition approved in 2016 as F3187 – 16. DOI: Available from American Welding Society (AWS), 8669 NW 36 St., #130,
10.1520/F3187-16R23. Miami, FL 33166-6672, http://www.aws.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3187 − 16 (2023)
A5.14/A5.14M Specification for Nickel and Nickel-Alloy 3.2.4.1 Discussion—Arc processes suitable for DED are
Bare Welding Electrodes and Rods based ostensibly on the gas shielded processes, namely GTA,
A5.16/A5.16M Specification for Titanium and Titanium- PA, PTA, and GMA, and variants thereof.
Alloy Welding Electrodes and Rods
3.2.5 as built, adj—see as built, ISO 52900, and 3.3.
2.6 DIN Standard:
3.2.6 build platform, n—see build platform. ISO/ASTM
DIN 4188 Screening Surfaces; Wire Screens for Test Sieves,
Dimensions
3.2.6.1 Discussion—In ISO/ASTM 52900, the build plat-
2.7 ISO Standards:
form of a machine is defined as the base which provides a
ISO 9001 Quality Management Systems: Requirements
surface upon which the building of the part/s is started and
ISO 6983-2 Numerical control of machines – Program
supported throughout the build process. In DED, the build
format and definition of address words – Part 1: Data
platform can also be a component that is to be repaired, and
format for positioning, line motion and contouring control
may also be non-planar.
systems
3.2.7 capture effıciency, n—fraction of powder ejected from
ISO 565:1990 Test sieves – Metal wire cloth, perforated
the deposition head that is incorporated into the built structure.
metal plate and electroformed sheet -- Nominal sizes of
Usually expressed in percent.
openings
3.2.8 carrier gas, n—gas, typically inert, used to transport
2.8 NFPA Standard:
the powder from the deposition head to the melt pool and also
NFPA 484 Standard for Combustible Metals
in some systems to assist the transport of powder from the
2.9 OSHA Standards:
storage system to the deposition head.
CFR Title 29, Chapter XVII, Part 1910 Occupational Safety
3.2.9 cast, n—of a wire, diameter of the circle formed by a
and Health Standards
length of wire thrown loosely on the floor.
OSHA Standards Checklist: Volume 15 Welding, Cutting
3.2.10 cladding, n—see cladding, AWS A3.0/A3.0M.
and Brazing
3.2.11 cross stream, n—flow, normally of inert gas, directed
3. Terminology
perpendicular to the optical axis of the lens being protected.
3.1 DED Technology draws its terminology from several
3.2.12 cycle, n—single cycle in which one or more
sources, particularly from the 3D printing and welding indus-
components, features or repairs are built up in layers in the
tries. Section 3.2 lists the terminology used in this guide, with
build space of the machine. ISO/ASTM 52900
many definitions referring simply to other standards issued by
3.2.12.1 Discussion—DED is well suited to repair, feature
ASTM, ISO or AWS. Section 3.3 is then provided for the
addition and remanufacturing applications. Throughout this
reader’s convenience, re-listing some of the definitions most
guide, the use of the terms “DED Build Cycle” and “DED
important to an understanding of DED so the reader of this
Deposition Cycle” are synonymous, irrespective of whether a
guide does not have to cross-reference numerous other sources
complete part is built, or a portion thereof, or a repair.
of information simply be able to read this guide. Please note,
3.2.13 defect, n—see defect, Terminology E1316.
however, that the definitions given in 3.3 are NOT kept
3.2.14 deposition head, n—the device that delivers the
up-to-date as the official definitions of these terms. The reader
energy and feedstock to the melt pool.
needing the most up-to-date definition should reference the
3.2.15 deposition rate, n—see deposition rate, AWS A3.0/
other sources listed.
A3.0M.
3.2 Definitions of Terms Specific to This Standard:
3.2.16 directed energy deposition (DED), n—see ISO/
3.2.1 active gases, n—gases, including those containing
ASTM 52900 and 3.3.
carbon dioxide, oxygen, hydrogen and, in some cases, nitro-
gen. Most of these gases, which in large quantities, would
3.2.17 feed, n—a mechanism which delivers material, in the
damage the deposit, when used in small, controlled quantities,
form of wire or powder, to the melt pool.
can improve deposit characteristics.
3.2.18 filler metal, n—see filler metal, AWS A3.0/A3.0M.
3.2.2 agglomerates, n—cluster of primary particles held
3.2.19 flaw, n—see flaw, Terminology E1316.
together by weak physical interactions.
3.2.20 focal spot, n—see focal spot, AWS A3.0/A3.0M.
3.2.3 alloy, n—see alloy, AWS A3.0/A3.0M.
3.2.21 functionally graded material, n—depostied material
3.2.4 arc plasma, n—an ionized gas, used in all arc welding
that varies spatially in composition or structure, or both,
process, through which an electric current flows.
resulting in corresponding changes in the properties of the
material.
3.2.22 gas metal arc (GMA), n—see gas metal arc welding
Available from International Organization for Standardization (ISO), ISO
(GMAW), AWS A3.0/A3.0M.
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
Geneva, Switzerland, http://www.iso.org.
3.2.22.1 Discussion—The word “welding” in the AWS defi-
Available from National Fire Protection Association (NFPA), 1 Batterymarch
nition conveys the joining of two or more pieces of material.
Park, Quincy, MA 02169-7471, http://www.nfpa.org.
As this is not the case for DED, the word “welding” is dropped.
Available from National Safety Council (NSC), 1121 Spring Lake Dr., Itasca,
IL 60143-3201, http://www.nsc.org. The remaining term characterizes the arc physics.
F3187 − 16 (2023)
3.2.23 gas porosity, n—property, presence of small voids in 3.2.36 manufacturing lot, n—see ISO/ASTM 52900.
a part making it less than fully dense.
3.2.37 manufacturing plan, n—a document that the pur-
chaser may require in order to control the quality and repeat-
3.2.23.1 Discussion—gas-filled flaws can form during the
ability of a deposition. A plan includes, but is not limited to the
DED process or subsequent post-processing that remain in the
production sequence, machine parameters, manufacturing con-
metal after it has cooled. This occurs because most liquid
trol system used in the production run, and quality checks.
materials can hold a large amount of dissolved gas, but the
3.2.37.1 Discussion—Manufacturing plans are typically re-
solid form of the same material cannot, so the gas forms flaws
quired under a quality management system such as ISO-9001
within the material as it cools. Gas porosity may present itself
and ASQ C-1.
on the surface of the DED deposit or the flaw may be trapped
inside the metal, which reduces strength in that vicinity.
3.2.38 melt pool, n—the region of material melted by the
3.2.24 gas tungsten arc (GTA), n—see gas tungsten arc
heat source.
welding (GTAW), AWS A3.0/A3.0M.
3.2.39 minimum explosible concentration (MEC), n—the
3.2.24.1 Discussion—See Discussion in 3.2.22.
minimum concentration of a combustible dust cloud that is
3.2.25 glovebox, n—typically a hermetically-sealed build
capable of propagating a deflagration through a well dispersed
space or chamber, normally filled with an inert gas, within
mixture of the dust and air under the specified conditions of
which material processing may occur. The chamber usually
test. E1515
includes gloves, through which an operator may reach to
3.2.40 mixed powder, n—powder composed of two or more
manipulate components within the chamber without breaking
constituent powders of different compositions.
the seal, hence the name.
3.2.40.1 Discussion—The DED process allows both the use
3.2.26 hatch spacing, n—the lateral distance between
of powders mixed prior to the start of the deposition and also
subsequent, adjacent passes of the deposition head whilst
mixing of powders enroute to the deposition head during the
depositing a layer.
deposition.
3.2.27 heat, n—see definition for powder lot per ISO/ASTM
3.2.41 near net shape, n—condition where the components
52900.
require little post processing to meet dimensional tolerance.
3.2.28 helix, n—of a wire, the vertical distance between one
3.2.42 plasma arc (PA), n—see plasma arc welding (PAW),
end of a wire and the other end formed by a length of spooled
AWS A3.0/A3.0M.
wire thrown loosely on the floor. Helix can also be referred to
3.2.42.1 Discussion—See Discussion in 3.2.22.
as “pitch”.
3.2.43 plasma transferred arc (PTA), n—Plasma Trans-
3.2.29 hopper, n—the converging portion of a bin. D6128
ferred Arc (PTA) is a constricted arc process similar to Plasma
3.2.30 inert gas, n—see inert gas AWS, A3.0/A3.0M.
Arc Welding (PAW) in most respects. The arc is constricted
using a water-cooled small diameter nozzle which reduces the
3.2.31 intermetallic phases, n—compounds, or intermediate
arc diameter and increases its power density. PTA differs from
solid solutions, containing two or more elements, which
PAW inasmuch as it is used predominantly as a surfacing
usually have characteristic properties and crystal structures
process rather than a joining process. PTA also usually uses
different from those of the pure metals or the terminal solid
powder feed delivery (through powder ports in the nozzle or an
solutions. E7
annular feed around the nozzle) so is more flexible in terms of
3.2.32 interpass temperature, n—see interpass temperature,
the alloys that can be deposited, since more alloys tend to be
AWS A3.0/A3.0M.
commercially available in powder form than in wire form.
3.2.33 interpass time, n—the length of time between ending
3.2.44 powder blend, n—quantity of powder made by thor-
a particular layer and starting the next layer, or the length of
oughly intermingling powders originating from one or several
time between individual beads.
powder lots of the same nominal composition.
3.2.33.1 Discussion—Further to the AWS definition, in
3.2.44.1 Discussion—A common type of powder blend
DED a common practice is to deposit multiple adjacent
consists of a combination of virgin and used powder. The
deposition beads in succession (as when following a hatch
specific requirements for a powder blend are typically deter-
pattern on a layer), and then allow the entire layer to cool
mined by the application, or by agreement between the supplier
before commencing the next layer. When this term is used in
and end-user.
DED, it should be specified whether it refers to a dwell
3.2.44.2 Discussion—In traditional powder metallurgy, a
between the deposition of individual beads or entire layers.
distinction is made between blended powders and mixed
3.2.34 lack of fusion, n—flaws caused by incomplete fusion
powders, in which case blended powders start with nominally
between the deposited metal and previously-deposited metal.
identical composition and particle morphology, whereas mixed
3.2.35 layer thickness, n—programmed distance between powders are composed of powders of different compositions.
one layer of the deposited material and the subsequent layer. See definition for mixed powder.
3.2.35.1 Discussion—The programmed layer thickness may 3.2.44.3 Discussion—If combined during the deposition
differ from the actual layer thickness obtained. The actual layer process, for example by loading different powders into differ-
thickness is determined by factors such as the power, feedstock ent feeders and combining at the point of deposition, the
feed rate and travel speed. correct term is “mix”.
F3187 − 16 (2023)
3.2.45 powder feeder, n—see powder feeder, AWS A3.0/ 3.3.2.1 Discussion—Focused thermal energy means that an
A3.0M. energy source (for example, laser electron beam, or plasma arc)
is focused to melt the materials being deposited.
3.2.46 powder lot, n—see powder lot, ISO/ASTM 52900.
3.3.2.2 Discussion—In contrast, “powder bed” processes
3.2.47 pre-heat temperature, n—see pre-heat temperature,
lay powder material out in a layer in a first step, and then direct
AWS A3.0/A3.0M.
thermal energy to melt the material as a second, subsequent
3.2.48 pre-run step(s), n—controlled process steps to be
step. In directed energy deposition, the provision of feedstock
completed prior to commencing DED material deposition.
occurs at the same time as the provision of the focused thermal
3.2.49 production run, n—See ISO/ASTM 52900. energy.
3.4 Terminology relating to additive manufacturing in ISO/
3.2.50 purge, v—to flush a gas supply system or component
ASTM 52900 shall apply.
with a regulated flow of gas F327
3.2.51 repair lot, n—repaired components having common-
4. Summary of Guide
ality between feedstock lot, production run, machine, and
post-processing steps (if required) as reported in single repair 4.1 This guide is intended to provide users of directed
work order. energy deposition technology information useful for the speci-
fication or use of the technology, including technology appli-
3.2.52 residual stress, n—see residual stress, AWS A3.0/
cation and limits, DED system set-up, machine operation,
A3.0M.
documentation, work practices, and system and process moni-
3.2.53 reused powder, n—see ISO/ASTM .
toring.
3.2.54 screed, v—to remove excess material using a straight
4.2 This guide is arranged as follows:
edge to leave a uniform layer of powder on the build platform.
4.2.1 Section 5 contains a high-level description of the
3.2.55 secondary processing, n—manufacturing steps re-
features and benefits of DED, and makes some comparisons
quired to achieve a finished form that take place after the DED
between DED and other metal 3D printing technologies.
process is complete. Often also referred to as post-processing.
4.2.2 Section 6 describes the machines used to perform
3.2.56 shielding gas, n—see shielding gas, AWS A3.0/
DED. Since the DED process can take several forms, the reader
A3.0M.
should be careful to understand the different types of DED
(laser/powder, electron beam/wire, arc/wire, etc.) and note
3.2.57 sieve analysis, n—the particle size distribution of a
which pieces of equipment are normally required for each
particulate or granular solid or sample thereof, when deter-
process.
mined by passage through and retention on a graded set of
4.2.3 Section 7 discusses atmosphere control, which is an
sieves. C1145
important part of all DED processes. All materials and
3.2.58 substrate, n—the material, work piece, part, compo-
processes, to some extent, require the removal of air and
nent or substance which provides the area on which the
perhaps the addition of some inert gas to prevent oxidation.
material is deposited.
4.2.4 Section 8 concerns the feedback used for DED,
3.2.59 trailing shield, n—inert shielding gas applied to
principally metal powder or metal wire. The features of each
material trailing behind the melt pool, or a mechanical device
are discussed, and the importance of proper cleanliness and
or structure that helps contain inert shielding gas around
safety practices discussed.
material trailing the melt pool.
4.2.5 Section 9 details the DED process itself, particularly
3.2.60 virgin powder, n—see ISO/ASTM 52900.
how to define, measure and control the key process variables.
3.2.61 voids, n—flaws created during the build process that
4.2.6 Section 10 defines how to set-up, calibrate and main-
are empty or filled with partially or wholly unsintered or
tain a DED machine, so that the user can be sure that the DED
un-fused powder or wire creating pockets. Voids are distinct
process is operated in a reliable, repeatable manner in produc-
from gas porosity, and are the result of lack of fusion and
tion.
skipped layers parallel or perpendicular to the build direction.
4.2.7 Section 11 is concerned with post-processing of DED-
Voids are also distinct from intentionally added open cells that
produced material. A description of common inspection
reduce weight. Like gas porosity, voids cause a part to be less
techniques, heat-treatments, and surface finishing processes is
than fully dense.
provided.
3.3 Definitions:
4.2.8 Section 12 provides an overview of safety concerns to
3.3.1 as built, adj—refers to the state of components made be aware of when using DED. Note that this safety section
by DED before any post-processing, except where removal
provides an overview only, and does not provide complete
from a base plate is necessary, or powder removal or support safety practices to be employed.
removal is required. ISO/ASTM 52900
4.2.9 Section 13 describes how to put together a manufac-
turing plan that could be used to implement DED in a
3.3.2 directed energy deposition (DED), n—an additive
production setting.
manufacturing process in which focused thermal energy is used
to fuse materials by melting as they are being deposited. 4.2.10 Finally, Section 14 describes how to specify a DED
ISO/ASTM 52900 process. This can be used to assist in communication between
F3187 − 16 (2023)
suppliers, buyers, and users of DED technology to make sure source, and the deposition head (typically) indexes up from the
all important details are communicated, recorded, and imple- build surface with each successive layer.
mented.
5.3 Although DED systems can be used to apply a surface
cladding, such use does not fit the current definition of AM.
5. Significance and Use
Cladding consists of applying a uniform buildup of material on
5.1 This guide applies to directed energy deposition (DED)
a surface. To be considered AM, a computer aided design
systems and processes, including electron beam, laser beam,
(CAD) file of the build features is converted into section cuts
and arc plasma based systems, as well as applicable material
representing each layer of material to be deposited. The DED
systems.
machine then builds up material, layer-by-layer, so material is
only applied where required to produce a part, add a feature or
5.2 Directed energy deposition (DED) systems have the
following general collection of characteristics: ability to pro- make a repair.
cess large build volumes (>1000 mm ), ability to process at
5.4 DED has the ability to produce relatively large parts
relatively high deposition rates, use of articulated energy
requiring minimal tooling and relatively little secondary pro-
sources, efficient energy utilization (electron beam and arc
cessing. In addition, DED processes can be used to produce
plasma), strong energy coupling to feedstock (electron beam
components with composition gradients, or hybrid structures
and arc plasma), feedstock delivered directly to the melt pool,
consisting of multiple materials having different compositions
ability to deposit directly onto existing components, and
and structures. DED processes are also commonly used for
potential to change chemical composition within a build to
component repair and feature addition.
produce functionally graded materials. Feedstock for DED is
delivered to the melt pool in coordination with the energy 5.5 Fig. 1 gives a general guide as to the relative capabilities
FIG. 1 Comparison of Various Metal Additive Manufacturing Processes
NOTE 1—In this figure, Build Volume refers to the relative size of components that can be processed by the subject process. Detail Resolution refers
to the ability of the process to create small features. Deposition Rate refers to the rate at which a given mass of product can be produced. Coupling
Efficiency refers to the efficiency of energy transfer from the energy source to the substrate, and Potential for Contamination refers to the potential to
entrain dirt, gas, and other possible contaminants within the part.
F3187 − 16 (2023)
of the main DED processes compared to others currently used through rapid beam manipulation to allow for large bead sizes.
for metal additive manufacturing. The figure does not include One feature of this process is the large standoff distance from
all process selection criteria, and it is not intended to be used the gun to the work piece that can be employed, which can be
as a process selection method. over 300 mm. In contrast, the working distance for arc
processes is typically less than 25 mm. This large standoff can
6. Machine
provide room for sensors or other ancillary equipment, and can
help avoid collisions with the part, especially with non-planar
6.1 The machine is defined in ISO/ASTM 52900 as the
substrates. The vacuum in which the electron beam typically
section of the additive manufacturing system including
operates can result in marked evaporation of volatile alloying
hardware, machine control software, required set-up software
elements; hence feedstock chemistry may require modification
and peripheral accessories necessary to complete a build cycle
to achieve acceptable final chemistry.
for producing parts. The DED machine often includes hard-
6.3.1.3 Arc-based DED systems can function with a wide
ware and software of differing natures to other 3D printing
range of power densities and deposition rates, with high
equipment, and even differing substantially among the various
electrical power efficiency. Arc energy sources can provide a
types of DED.
low cost heat source that enables intermediate energy density.
6.2 A DED system comprises four fundamental subcompo-
The arc can be manipulated to deliver the heat in a variety of
nents: heat source, positioner, feedstock feed mechanism, and
ways including pulsing with a variety of waveforms and
a computer control system. DED systems come in many
frequency. This may help reduce overall heat input to the work
shapes, sizes, and types, and commonly use laser, electron
piece. Since arc welding power sources are readily available,
beam, or arc plasma heat sources. In all systems, the feedstock
they can be converted to a 3D build system by combining the
is fed directly to the junction of the heat source and the work
power source with an adequate controller and a multi-axis
piece. From there, the advantages of the different heat sources
positioner. Today’s computer control systems easily control the
begin to assert themselves. Laser and electron beam (EB) have
power source and positioner. System maintenance is often
significant standoff capability and have very high energy
straightforward since many organizations already have capa-
density at the work piece compared to arc sources. On the other
bility to maintain welding power sources. Arc sources are
hand, an arc system can be less costly. Thus, each system,
particularly useful for performing repair. This is true of all
distinguished by its heat source and feedstock, brings certain
DED systems but particularly so for arcs due to their low cost
capabilities to 3D building and repair. Those capabilities are
and flexibility of implementation.
briefly elaborated upon below and should be kept in mind when
6.4 Motion Device to Manipulate the Heat Source, the
procuring or using a system. The parts of the system are as
Substrate, or Both:
follows:
6.4.1 Motion is achieved either by moving the heat source
6.3 Directed Energy Deposition (DED) Heat Source:
relative to a stationary component, or moving the component
6.3.1 Common heat sources include a laser (CO , Nd:YAG,
relative to a stationary heat source, or a combination of these
fiber, disk or direct diode), electron beam, or arc plasma
methods. Motion is typically provided in at least three orthogo-
(typically GTA, GMA, PTA). Heat sources can range in power
nal axes. Linear motion elements may be ball screw, toothed
from less than 1 kW to 60 kW or more depending on the size,
belt, rack and pinion, or other types. In addition, rotary axes
shape and function of the intended part, and the desired
may be employed to rotate or tip and tilt the part, to tip and tilt
metallurgical structure for the particular application.
the end effector, or both. The molten pool can be affected by
6.3.1.1 Laser-based DED systems utilize laser beams, with
gravity, placing a limit on the substrate angle. For certain part
beam delivery or fiber delivery, or both, and focusing optics, to
geometries, therefore, it may be desirable to tip and tilt the part.
provide highly controllable energy to localized regions of the
Integrated motion of auxiliary axes (rotary, tilt axes), working
substrate. Feedstock can take the form of powder or wire. Laser
with the main motion control axis (Cartesian gantry or 6-axis
electrical efficiency can be as high as 30 %, and coupling
robotic arm), are typically used. Such systems provide for a
efficiency (that is, energy absorption by substrate) ranges from
wide array of working envelopes and thus the ability to build
5–40 % or higher depending on laser wavelength and
large or small parts, as desired, based on the motion system
feedstock/substrate material. Optics can be varied to produce
design and working envelope.
spots as small as 50 microns diameter to produce small
6.5 Device to Feed the Powder or Wire Feedstock:
features, or lines up to 25 mm wide or more for large
depositions. Typical laser powers for production AM systems 6.5.1 Powder Feeder:
currently range from 400–4,000 W, although higher power 6.5.1.1 The purpose of the powder feeder is to deliver
systems exist. Like arc-based systems, they can be operated in powder feedstock to the interaction zone in a robust and
non-vacuum environments and thus have potential for large consistent manner. Powder feed systems typically include a
volume builds (in certain materials) or for deposition in the powder hopper that serves as a reservoir for the powder,
field. plumbing to link the hopper to the nozzles, carrier gas, and a
6.3.1.2 DED electron beam systems are capable of provid- computer controlled feeding mechanism. Some require gravity
ing relatively high power compared to lasers, and consequent to aid in powder delivery, and others do not. If high pressure
high deposition rates with reasonable electrical power effi- carrier gas is employed, a pressure relief valve is incorporated
ciency. Generally, the energy density is very high compared to into the line to prevent blow-out in case of a clogged nozzle or
lasers. However, the average energy density is easily varied obstruction in the line. Powder capture efficiencies can vary
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widely (5–95 %), with 40–80 % being typical. Powder mass For precision feed, an auger-type feeder is usually employed,
flow rates fall typically between 1 and 50 g/min. with argon carrier gas to deliver the powder from the hopper to
the deposition head. Powder feed ports are typically single,
6.5.1.2 Powder feedstock works more reliably when applied
in a “down-hand” orientation; in other words, gravity assists triple (120 degrees apart), quad (90 degrees apart), or concen-
tric annular arrangements around the nozzle. Such systems
powder transport from the deposition head to the melt pool.
The powder enhances absorption, leading to robust production usually have integrated feed tubes and nozzles such that the
of low heat and low dilution depositions. Generally, not all powder can be accurately fed in the correct relationship to the
powder feedstock is melted and incorporated into the melt
melt pool to maximize powder capture and deposition efficien-
pool. Though reuse of powder is possible in many cases,
cies. Dual powder feeders can be employed to feed different
accidental powder contamination (for example from dirt,
powders and allow a metallurgically and functionally graded
lubricants, powder agglomerates, unfused powder exposed to
composition to be produced by varying the feed rate of each
high temperatures and thus oxidized, etc.) may yield undesir-
powder separately.
able material properties, and in some cases excess powder may
6.5.2 Wire Feeder:
not be able to be reused, and thus is wasted (unless it is fully
6.5.2.1 Wire feeder selection is dependent on the type of
recycled via remelting by the powder supplier). Powder can be
wire to be fed, the diameter of wire to be fed and other process
fed from the side of, or co-axial to, the energy source. Coaxial
considerations, for example, pulsing or hot wire capability.
feedstock delivery simplifies multi-directional depositions, and
Wire feeder systems generally utilize either two or four drive
can simplify motion programming. Powders can be mixed
rollers. Systems utilizing two drive rollers are usually used in
during delivery to produce unique alloy compositions or to
compact systems for feeding small diameter wire. Systems
grade materials to ensure material compatibility, for example,
utilizing four drive rollers are usually used in large systems for
from a low-cost substrate to a wear or corrosion-resistant layer,
feeding large diameter wire at high rates or longer distances, or
or both.
both. The system may also include a wire straightener to
6.5.1.3 There are a variety of commercially available pow-
remove the cast and helix resulting from winding the wire on
der feed technologies that can fulfill this need. Many
a spool. Drive roller selection is an important consideration and
accessories, such as vibrators to reduce clogging, heaters to
must be matched to wire type and diameter. Soft wires, such as
preheat the powder, and mixers to enable creation of unique
aluminum, typically use a U-groove to avoid flattening the
alloys or grading of materials to achieve locally engineered
wire. Harder wires, such as titanium or steel alloys, typically
properties, are common to the different powder feed options.
use either a V-groove or textured surface to avoid slippage. In
Mass-based closed loop feedback control may also be avail-
order to avoid buckling, or “birdnesting”, it is important to
able.
provide support for the wire from the output of the drive rollers
6.5.1.4 Powder feeders that utilize a worm gear or screw to
to the delivery point. This becomes more important with softer
feed powder consistently have been used for many years for
wires such as aluminum alloys.
high mass flow rate processes such as plasma arc deposition
6.5.2.2 Due to a large arc welding market, wire feedstock is
and cold spray. They employ a carrier gas to feed the powder
readily available from a variety of sources in a wide range of
and are not gravity fed. They can operate with non-spherical
weldable alloys. Additionally, most of the feedstock is con-
powders (which are not optimal for delivery methods requiring
sumed during the process, so wasted material, process waste
flowability) between 5 and 150 microns in size. If the powder
stream, and any need to reuse or recycle feedstock are
hopper is located below the delivery area such that gravity is
minimized. Readily available wire diameters range from 0.75
not aiding powder flow, then high carrier gas flow rates may be
to 3 mm or greater for many materials. Smaller and larger
necessary, which can result in turbulence that is detrimental to
the deposition process. diameters can be custom made. Smaller diameter wires can
provide a higher level of detail in the deposit, but at a reduced
6.5.1.5 Gravity fed systems have also been developed, and
deposition rate. Larger diameters can help dramatically in-
come in two basic categories; mechanical wheel or disk-based
crease deposition rate, as the deposition rate is proportional to
systems and gas fluidized systems. Systems in the first category
the square of the diameter, with an appropriate increase in the
typically utilize wheels or disks that are fashioned with “cups”
energy input. However, this increase in deposition rate comes
that apportion a specific amount of powder each revolution,
at the cost of reduced level of detail in the deposit.
and whose speed is controlled by the operator to set powder
mass flow rate. Utilizing highly flowable, spherical powders is
6.5.2.3 Modern wire feeders provide the capability to pulse,
more important with these systems, and very small powder
where the wire feed rate is pulsed in the range of tens or
sizes can result in clogging within powder lines.
hundreds of Hz, in synch with the heat source. This enables an
6.5.1.6 The second category of gravity-fed powder feeders efficient use of energy during deposition, that is the maximum
uses gas coupled with vibrators to fluidize powder within the wire feed rate is used when the maximum heat pulse is
hopper, and another gas stream to feed the powder to the
employed. This can assist in minimizing total heat input. Wire
processing region. Due to the fluidizing action, these systems pulsing is limited by the capability of the electro-mechanical
can flow smaller diameter powders, in the range of 2–200
system to actually match the frequency of the heat pulse.
microns, at 5–300 g/min.
Finally, the pulsing of the wire can give a relatively fine surface
finish when used properly. Typically, finer surface finishes
6.5.1.7 For powder fed systems it is usual to employ a
powder feed configuration with a feed hopper and carrier gas. result from higher frequencies.
F3187 − 16 (2023)
6.5.2.4 In a hot wire feed system the wire is heated prior to thus keeping the interior components, particularly the optics,
entering the melt pool. This may improve deposition rate for a clean. The purge is also used to provide an inert shielding gas
given heat source power, as less heat is required to melt the
over the melt pool, thus reducing oxygen levels around the
wire. It may also improve the level of detail and surface melt pool (which reduces oxidation) and thereby improving the
appearance, as a smaller melt pool may be used. This approach quality of the deposited metal. This forced flow also serves to
may currently be used with laser, arc or electron beam heat increase convective cooling of the substrate, when compared to
sources. natural convection alone.
(g) Powder Delivery Nozzles—The powder may be deliv-
6.5.3 Deposition Head:
ered in several ways, but all are designed to provide a steady
6.5.3.1 The Deposition head, also sometimes known simply
stream of metal powder aimed generally at the melt pool. The
as the “head”, or the “end effector”, is the device that delivers
powder may be delivered through one or more discrete nozzles
the energy and feedstock to the melt pool. The deposition head
surrounding the purge nozzle or can be delivered from a single
is often only centimeters from the melt pool, and if so, must be
direction. Alternatively, there may be a cone arrangement
designed to be durable to withstand the heat and reflected
where there is effectively one powder nozzle that completely
energy from the melt pool.
surrounds the purge nozzle. This arrangement may be referred
6.5.3.2 Common Features—Laser powder deposition head.
to as a coaxial nozzle.
(1) A deposition head used for laser powder deposition
6.5.3.3 Important considerations for the laser powder depo-
may have the following common features:
sition head include:
(a) Laser Collimator—The laser is often delivered to the
(1) Heat Load—The deposition head may be heated by the
deposition head through a fiber, or direct from the laser in the
laser beam itself as it passes through the head, as well as by
case of CO lasers. If fiber delivered, the end of the deposition
heat radiating from the melt pool. As the laser power increases
head furthest from the melt pool often consists of the laser
beyond 1 kW, active cooling is typically required, and may
fiber, and a collimator. The collimator’s purpose is to expand
become a significant design consideration as the power in-
the laser beam and collimate it so that it moves straight through
creases beyond 4 kW. Heat can cause the laser optics to break,
the deposition head to the focusing lens. Collimators are often
or distort, and can increase the likelihood of powder becoming
provided by the laser manufacturer or specialty laser optics
stuck in and clogging the powder nozzles rather than exiting
providers.
freely.
(b) Beam Shapers/Redirection—After the collimator, the
(2) Atmosphere Control—When laser powder deposition
deposition head may contain other laser optical elements to
occurs in a fully contained inert atmosphere, such as provided
serve specific purposes. For example, the laser beam may be
by a glovebox, the deposition head may not need to provide
converted to a rectangular shape rather than a round beam, or
additional shielding gas. When laser powder deposition occurs
it may be turned by 90 degrees if necessary for the specific
in an open environment, the deposition head must be
configuration of the system.
employed, in part to provide a local shield of inert gas onto and
(c) Sensors—Many deposition heads contain sensors,
around the melt pool. Inert gas flowing through the deposition
such as vision cameras, thermal imaging cameras, or closed-
head to deliver feedstock or protect optics can also assist in
loop controls. The sensors may view the melt-pool directly, or
shielding the molten pool and substrate during deposition.
may view the melt pool via a beam-splitter, which can be used
(3) Alignment and Adjustability—Most deposition heads
to enable multiple sensors to view the melt pool together.
offer some degree of adjustability. These may include adjusting
(d) Focusing Optic—The focusing optic focuses the col-
the focal position of the laser, adjusting the focal position of the
limated laser beam onto the work piece. Typically, transmissive
powder, etc. It is usually important to ensure that the powder
optics are used for this purpose, though reflective optics are
focal point is coincident with the laser beam at the substrate.
sometimes used with high power laser beams. The focal length
6.5.3.4 Common Features—Electron beam wire deposition
for this optic is often in the range of 150–200 mm. The lens
head.
may be water-cooled, particularly if the deposition head is
(1) A deposition head used for electron beam wire deposi-
operating at high power. This water cooling is normally
tion may have the following common features:
provided by cooling the lens holder.
(a) Focusing Coils—Electron beam guns used for DED
(e) Cover Glass—After the focusing lens, the laser beam
typically use a focused electron beam, rather than a wide,
then typically passes through a cover glass slide, which is a
defocused beam, in order to control the size of the melt pool.
replaceable optic designed to keep the more expensive focus-
Electromagnetic coils are used to control beam focus over the,
ing optics clean. The cover glass may become dirty during use,
due to fumes and spatter from the melt pool. When overly dirty, typically, large working envelope of the electron beam gun.
Focal spot size can range from fractions of a millimeter to
the cover glass can affect the transmitted laser energy and must
be replaced. Some means to easily remove and replace the several millimeters in diameter.
(b) Deflection Coils—The electron beam may be magneti-
cover glass is often employed.
(f) Purge Nozzle—Close to the workpiece, the laser nor- cally deflected at very high rates to provide several process
functions. The focused beam may be deflected in a pattern
mally passes through a final orifice, through which inert gas is
usually flowing toward the workpiece. This inert gas purge can designed to control the width of the melt pool. The beam may
serve two purposes. The flow of gas impedes the ingress of also be “time shared” to provide pre- or post-heat of the
spatter and fumes from the workpiece into the deposition head, deposit, as well as other functionality.
F3187 − 16 (2023)
(c) Sensors—Modern electron beam guns typically have 6.5.4.1 All DED processes require careful control of the
coaxial camera systems, which provide a view of the melt pool. working environment. To ensure that the deposited metal is
free of gaseous contamination, appropriate processing environ-
Other sensors, such as IR cameras, spectrometers and closed
ments need to be considered for each type of heat source: laser
loop control systems may be incorporated.
beam, electron beam, and arc plasma.
(d) Wire Delivery Nozzles—One or more wire delivery
nozzles may be attached to the deposition head. Multiple wire 6.5.4.2 DED systems that use localized shielding will typi-
feeders provide increased process flexibility. cally be able to accommodate larger parts than
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