EN ISO/ASTM 52911-1:2019

Additive manufacturing - Design - Part 1: Laser-based powder bed fusion of metals (ISO/ASTM 52911-1:2019)

This document specifies the features of laser-based powder bed fusion of metals (PBF-LB/M) and provides detailed design recommendations.
Some of the fundamental principles are also applicable to other additive manufacturing (AM) processes, provided that due consideration is given to process-specific features.
This document also provides a state of the art review of design guidelines associated with the use of powder bed fusion (PBF) by bringing together relevant knowledge about this process and by extending the scope of ISO/ASTM 52910.

Additive Fertigung - Konstruktion - Teil 1: Laserbasierte Pulverbettfusion von Metallen (ISO/ASTM 52911-1:2019)

Dieses Dokument legt die Merkmale der laserbasierten Pulverbettfusion von Metallen (PBF LB/M) fest und bietet detaillierte Konstruktionsempfehlungen.
Einige der grundlegenden Prinzipien gelten auch für andere additive Fertigungsverfahren (AM Verfahren), vorausgesetzt, dass die prozessspezifischen Merkmale berücksichtigt werden.
Dieses Dokument bietet eine Übersicht von Konstruktionsleitfäden auf dem Stand der Technik im Zusammen¬hang mit pulverbettbasiertem Schmelzen (PBF), indem relevantes Wissen zu diesem Verfahren zusammengeführt und der Anwendungsbereich von ISO/ASTM 52910 erweitert wird.

Fabrication additive - Conception - Partie 1: Fusion laser sur lit de poudre métallique (ISO/ASTM 52911-1:2019)

Le présent document spécifie les caractéristiques de la fusion laser sur lit de poudre métallique (PBF-LB/M) et fournit des recommandations de conception détaillées.
Certains des principes fondamentaux sont également applicables à d'autres procédés de fabrication additive (FA), sous réserve que les caractéristiques spécifiques à un procédé soient dûment prises en compte.
Le présent document fournit également un État de l'Art des lignes directrices de conception associées à l'utilisation d'une fusion sur lit de poudre (PBF), en compilant des connaissances pertinentes sur ce procédé et en élargissant le domaine d'application de l'ISO/ASTM 52910.

Dodajalna izdelava - Konstruiranje - 1. del: Spajanje kovinskega prahu na podlagi z laserskim žarkom (ISO/ASTM 52911-1:2019)

Namen tega standarda je zagotoviti inženirjem za načrtovanje in proizvodnjo delovno podlago, ki jim omogoča sprejemanje utemeljenih odločitev glede uporabe laserske fuzije kovinskih prahastih plasti. Ta standard opisuje značilnosti laserske fuzije kovinskih prahastih plasti in podaja podrobna priporočila za načrtovanje. Nekatera temeljna načela je mogoče uporabiti tudi pri drugih procesih aditivne proizvodnje, pod pogojem, da se upošteva značilnosti procesa. Namen tega standarda je izvajalcem pomagati raziskati prednosti laserske fuzije kovinskih prahastih plasti ter prepoznati omejitve, povezane s procesi, pri načrtovanju delov.
Dokument ponuja tudi najsodobnejši pregled smernic za načrtovanje, povezanih z uporabo fuzije prahastih plasti, ki združujejo ustrezno znanje o tem procesu in razširjajo področje uporabe standarda ISO/ASTM 52910, »Standardnega vodila za načrtovanje aditivne proizvodnje«.

General Information

• Status: Published
• Publication Date: 24-Sep-2019
• Withdrawal Date: 30-Mar-2020
• ICS: 25.030 - Additive manufacturing
• Technical Committee: CEN/TC 438 - Additive Manufacturing
• Drafting Committee: CEN/TC 438 - Additive Manufacturing
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 25-Sep-2019
• Completion Date: 25-Sep-2019
• Ref Project: SIST EN ISO/ASTM 52911-1:2019 - Additive manufacturing - Design - Part 1: Laser-based powder bed fusion of metals (ISO/ASTM 52911-1:2019)

Overview

EN ISO/ASTM 52911-1:2019 - Additive manufacturing - Design - Part 1: Laser‑based powder bed fusion of metals (PBF‑LB/M) is a CEN-adopted international standard that consolidates design guidance and a state‑of‑the‑art review for laser-based powder bed fusion of metals. It specifies features of the PBF‑LB/M process and provides detailed, practical design recommendations to help engineers and designers exploit the capabilities of metal powder bed fusion while managing its process‑specific constraints.

Key topics and technical requirements

The standard covers design-related aspects and process characteristics without prescribing machine settings. Major technical topics include:

• Characteristics of powder bed fusion (PBF) - general process description, typical part sizes, benefits and limitations of PBF‑LB/M.
• Feature constraints - guidance on islands, overhangs, and the stair‑step effect that influence geometry and surface finish.
• Dimensional, form and positional accuracy - considerations for achievable tolerances and factors affecting part fidelity.
• Data quality and representation - recommendations for digital model resolution and build data preparation.
• Design guidelines for PBF‑LB/M - material and structural considerations, recommended approaches to support structures, build orientation, part positioning and powder spreading.
• Thermal and mechanical effects - discussion of curl/warpage, anisotropy of material properties and their design implications.
• Surface roughness and post‑processing - strategies for surface finishing, powder removal, support removal, heat treatment and achieving final geometric tolerances.
• Design considerations - advice on cavities, gaps, minimum wall thicknesses, holes, channels, and integrated markings.
• Examples and materials - practical design examples (e.g., integral designs, gear geometry) and an informative annex on materials suitable for PBF‑LB/M.

The document references and extends ISO/ASTM 52910 design guidance and includes normative references and a bibliography for further reading.

Applications

EN ISO/ASTM 52911-1:2019 is practical for organizations designing metal parts for additive manufacturing, particularly when using laser‑based powder bed fusion. Typical applications include:

• Complex, lightweight structural components
• Internal cavities and conformal channels (e.g., cooling, fluidics)
• Prototypes and low‑volume production parts with high geometric complexity
• Functional parts requiring post‑processing and tight integration with traditional manufacturing

Who should use this standard

• Design engineers and CAD specialists creating parts for PBF‑LB/M
• Additive manufacturing process engineers and build planners
• Quality and production managers implementing AM workflows
• AM service providers, OEMs and technical procurement teams seeking standardized design practices

Related standards

• ISO/ASTM 52910 - General design guidelines for additive manufacturing, which EN ISO/ASTM 52911-1:2019 extends for PBF‑LB/M
• The EN/ISO/ASTM 52911 series - for additional parts and complementary guidance

This standard is essential for practitioners aiming to optimize part performance and manufacturability with laser‑based powder bed fusion, improving design decisions and reducing iterative build cycles.

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2019
Aditivna proizvodnja - Konstruiranje - 1. del: Selektivno lasersko pretaljevanje
kovinskega prahu (ISO/ASTM 52911-1:2019)
Additive manufacturing - Design - Part 1: Laser-based powder bed fusion of metals
(ISO/ASTM 52911-1:2019)
Additive Fertigung - Technische Konstruktionsrichtlinie für Pulverbettfusion - Teil 1:
Laserbasierte Pulverbettfusion von Metallen (ISO/ASTM 52911-1:2019)
Fabrication additive - Conception - Partie 1: Fusion laser sur lit de poudre métallique
(ISO/ASTM 52911-1:2019)
Ta slovenski standard je istoveten z: EN ISO/ASTM 52911-1:2019
ICS:
25.030 3D-tiskanje Additive manufacturing
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO/ASTM 52911-1
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2019
EUROPÄISCHE NORM
ICS 25.030
English Version
Additive manufacturing - Design - Part 1: Laser-based
powder bed fusion of metals (ISO/ASTM 52911-1:2019)
Fabrication additive - Conception - Partie 1: Fusion Additive Fertigung - Konstruktion - Teil 1:
laser sur lit de poudre métallique (ISO/ASTM 52911- Laserbasierte Pulverbettfusion von Metallen
1:2019) (ISO/ASTM 52911-1:2019)
This European Standard was approved by CEN on 21 July 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO/ASTM 52911-1:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO/ASTM 52911-1:2019) has been prepared by Technical Committee ISO/TC 261
"Additive manufacturing" in collaboration with Technical Committee CEN/TC 438 “Additive
Manufacturing” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2020, and conflicting national standards shall
be withdrawn at the latest by March 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO/ASTM 52911-1:2019 has been approved by CEN as EN ISO/ASTM 52911-1:2019
without any modification.
INTERNATIONAL ISO/ASTM
STANDARD 52911-1
First edition
2019-07
Additive manufacturing — Design —
Part 1:
Laser-based powder bed fusion of
metals
Fabrication additive — Conception —
Partie 1: Fusion laser sur lit de poudre métallique
Reference number
ISO/ASTM 52911-1:2019(E)
©
ISO/ASTM International 2019
ISO/ASTM 52911-1:2019(E)
© ISO/ASTM International 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be
reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester. In the United States, such requests should be sent to ASTM International.
ISO copyright office ASTM International
CP 401 • Ch. de Blandonnet 8 100 Barr Harbor Drive, PO Box C700
CH-1214 Vernier, Geneva West Conshohocken, PA 19428-2959, USA
Phone: [phone] Phone: [phone]
Fax: [phone] Fax: [phone]
Email: [e-mail] Email: [e-mail]
Website: www.iso.org Website: www.astm.org
Published in Switzerland
ii © ISO/ASTM International 2019 – All rights reserved

ISO/ASTM 52911-1:2019(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
4.1 Symbols . 2
4.2 Abbreviated terms . 3
5 Characteristics of powder bed fusion (PBF) processes . 3
5.1 General . 3
5.2 Size of the parts . 4
5.3 Benefits to be considered in regard to the PBF process . 4
5.4 Limitations to be considered in regard to the PBF process . 5
5.5 Economic and time efficiency . 5
5.6 Feature constraints (islands, overhang, stair-step effect) . 6
5.6.1 General. 6
5.6.2 Islands . 6
5.6.3 Overhang . 6
5.6.4 Stair-step effect . 6
5.7 Dimensional, form and positional accuracy . 7
5.8 Data quality, resolution, representation . 7
6 Design guidelines for laser-based powder bed fusion of metals (PBF-LB/M) .8
6.1 General . 8
6.1.1 Selecting PBF-LB/M . 8
6.1.2 Design and test cycles . 8
6.2 Material and structural characteristics . 8
6.3 Support structures . 9
6.4 Build orientation, positioning and arrangement .11
6.4.1 General.11
6.4.2 Powder spreading .11
6.4.3 Support structures design .12
6.4.4 Curl effect .13
6.5 Anisotropy of the material characteristics.14
6.6 Surface roughness .14
6.7 Post-production finishing .14
6.7.1 General.14
6.7.2 Surface finishing .15
6.7.3 Removal of powder residue .15
6.7.4 Removal of support structures .15
6.7.5 Adjusting geometric tolerances .15
6.7.6 Heat treatment.15
6.8 Design considerations.16
6.8.1 General.16
6.8.2 Cavities .16
6.8.3 Gaps .16
6.8.4 Wall thicknesses .16
6.8.5 Holes and channels .17
6.8.6 Integrated markings .17
6.9 Example applications .17
6.9.1 General.17
6.9.2 Integral design (provided by CETIM — Technical Centre for Mechanical
Industry) .17
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ISO/ASTM 52911-1:2019(E)
6.9.3 Gear wheel design (provided by Fraunhofer IGCV) .19
6.9.4 Impossible crossing (provided by TNO — The Netherlands Organisation
for applied scientific research) .20
Annex A (informative) Materials for PBF-LB/M .22
Bibliography .23
iv © ISO/ASTM International 2019 – All rights reserved

ISO/ASTM 52911-1:2019(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 261, Additive manufacturing, in
cooperation with ASTM F42, Additive Manufacturing Technologies, on the basis of a partnership
agreement between ISO and ASTM International with the aim to create a common set of ISO/ASTM
standards on additive manufacturing.
A list of all parts in the ISO 52911 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
© ISO/ASTM International 2019 – All rights reserved v

ISO/ASTM 52911-1:2019(E)
Introduction
Laser-based powder bed fusion of metals (PBF-LB/M) describes an additive manufacturing (AM)
process and offers an additional manufacturing option alongside established processes. PBF-LB/M has
the potential to reduce manufacturing time and costs, and increase part functionality. Practitioners
are aware of the strengths and weaknesses of conventional, long-established manufacturing processes,
such as cutting, joining and shaping processes (e.g. by machining, welding or injection moulding), and
of giving them appropriate consideration at the design stage and when selecting the manufacturing
process. In the case of PBF-LB/M and AM in general, design and manufacturing engineers only have
a limited pool of experience. Without the limitations associated with conventional processes, the
use of PBF-LB/M offers designers and manufacturers a high degree of freedom and this requires an
understanding about the possibilities and limitations of the process.
The ISO 52911 series provides guidance for different powder bed fusion (PBF) technologies. It is
1)
intended that the series will include this document on PBF-LB/M, ISO 52911-2 on laser-based powder
2)
bed fusion of polymers (PBF-LB/P), and ISO 52911-3 on electron beam powder bed fusion of metals
(PBF-EB/M). Each document in the series shares Clauses 1 to 5, where general information including
terminology and the PBF process is provided. The subsequent clauses focus on the specific technology.
This document is based on VDI 3405-3:2015. It provides support to technology users, such as design
and production engineers, when designing parts that need to be manufactured by means of PBF-LB/M.
It will help practitioners to explore the benefits of PBF-LB/M and to recognize the process-related
limitations when designing parts. It also builds on ISO/ASTM 52910 to extend the requirements,
guidelines and recommendations for AM design to include the PBF process.
1) Under preparation.
2) Under preparation.
vi © ISO/ASTM International 2019 – All rights reserved

INTERNATIONAL STANDARD ISO/ASTM 52911-1:2019(E)
Additive manufacturing — Design —
Part 1:
Laser-based powder bed fusion of metals
1 Scope
This document specifies the features of laser-based powder bed fusion of metals (PBF-LB/M) and
provides detailed design recommendations.
Some of the fundamental principles are also applicable to other additive manufacturing (AM) processes,
provided that due consideration is given to process-specific features.
This document also provides a state of the art review of design guidelines associated with the use of
powder bed fusion (PBF) by bringing together relevant knowledge about this process and by extending
the scope of ISO/ASTM 52910.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/ASTM 52900, Additive manufacturing — General principles — Fundamentals and vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/ASTM 52900 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
curl effect
thermal and residual stress effect
dimensional distortion as the printed part cools and solidifies after
being built or by poorly evacuated heat input
3.2
downskin area
D

(sub-)area where the normal vector n projection on the z-axis is negative
Note 1 to entry: See Figure 1.
© ISO/ASTM International 2019 – All rights reserved 1

ISO/ASTM 52911-1:2019(E)
3.3
downskin angle
δ
angle between the plane of the build platform and the downskin area (3.2) where the value lies between
0° (parallel to the build platform) and 90° (perpendicular to the build platform)
Note 1 to entry: See Figure 1.
3.4
upskin area
U

(sub-)area where the normal vector n projection on the z-axis is positive
Note 1 to entry: See Figure 1.
3.5
upskin angle
υ
angle between the plane of the build platform and the upskin area (3.4) where the value lies between 0°
(parallel to the build platform) and 90° (perpendicular to the build platform)
Note 1 to entry: See Figure 1.
Key
δ downskin angle

normal vector
n
D downskin (left) area
U upskin (right) area
υ upskin angle
SOURCE VDI 3405-3:2015.
Figure 1 — Orientation of the part surfaces relating to the build platform
4 Symbols and abbreviated terms
4.1 Symbols
The symbols given in Table 1 are used in this document.
2 © ISO/ASTM International 2019 – All rights reserved

ISO/ASTM 52911-1:2019(E)
Table 1 — Symbols
Symbol Designation Unit
a overhang mm
D downskin area mm
I island mm

normal vector —
n
R mean roughness µm
a
R average surface roughness µm
z
U upskin area mm
δ downskin angle °
υ upskin angle °
4.2 Abbreviated terms
The following abbreviated terms are used in this document.
AM additive manufacturing
AMF additive manufacturing file format
CT computed tomography
DICOM digital imaging and communications in medicine
HIP hot isostatic pressing
MRI magnetic resonance imaging
PBF powder bed fusion
PBF-EB/M electron beam powder bed fusion of metals
PBF-LB laser-based powder bed fusion
PBF-LB/M laser-based powder bed fusion of metals (also known as, for example, laser beam melting,
selective laser melting)
PBF-LB/P laser-based powder bed fusion of polymers (also known as, for example, laser beam
melting, selective laser melting)
STL stereolithography format or surface tessellation language
5 Characteristics of powder bed fusion (PBF) processes
5.1 General
Consideration shall be given to the specific characteristics of the manufacturing process used in order
to optimize the design of a part. Examples of the features of AM processes which need to be taken into
consideration during the design and process planning stages are listed in 5.2 to 5.8. With regards to
metal processing, a distinction can be made between, for example, laser-based PBF (applied for metals
and polymers) and electron beam-based PBF (applied for metals only).
Polymers PBF uses, in almost every case, low-power lasers to sinter polymer powders together. As with
polymer powders PBF, metals PBF includes varying processing techniques. Unlike polymers, metals
PBF often requires the addition of support structures (see 6.4.3). Metals PBF processes may use low-
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ISO/ASTM 52911-1:2019(E)
power lasers to bind powder particles by only melting the surface of the powder particles or high-power
(approximately 200 W to 1 kW) beams to fully melt and fuse the powder particles together.
Electron beam-based melting and laser-based melting have similar capabilities, although the beam
energy transferred from the electron beam to the metal is of a higher intensity and the process
most commonly operates at higher temperatures than the laser counterpart, therefore typically also
supporting faster build rates at lower resolutions. In general, since the powder bed is preheated and
kept close to the melting temperature during the building operation, electron beam processes subject
parts to less thermal induced stresses and have faster build rates, but the trade-off often comes with
much longer times needed for the build chamber to cool down after the build cycle has been completed,
and in general larger minimum feature sizes and greater surface roughness than laser melting.
5.2 Size of the parts
The size of the parts is not only limited by the working area/working volume of the PBF-machine. Also,
the occurrence of cracks and deformation due to residual stresses can limit the maximum part size.
Another important practical factor that can limit the maximum part size is the cost of production having
a direct relation to the size and volume of the part. Cost of production can be minimized by choosing
part location and build orientation in a way that allows nesting of as many parts as possible. The cost of
the volume of powder required to fill the bed should be considered. Powder reuse rules impact this cost
significantly. If no reuse is allowed then all powder is scrapped regardless of volume solidified.
5.3 Benefits to be considered in regard to the PBF process
PBF processes can be advantageous for manufacturing parts where the following points are relevant.
— Integration of multiple functions in the same part.
— Parts can be manufactured to near-net shape (i.e. close to the finished shape and size).
— Degrees of design freedom for parts are typically high. Limitations of conventional manufacturing
processes do not usually exist, e.g. for:
— tool accessibility, and
— undercuts.
— A wide range of complex geometries can be produced, such as:
— free-form geometries, e.g. organic structures,
— topologically optimized structures, in order to reduce mass and optimize mechanical
properties, and
— infill structures, e.g. honeycomb.
— The degree of part complexity is largely unrelated to production costs, unlike most conventional
manufacturing.
— Assembly and joining processes can be reduced through part consolidation, potentially achieving
en bloc construction.
— Overall part characteristics can be selectively configured by adjusting process parameters locally.
— Reduction in lead times from design to part production.
4 © ISO/ASTM International 2019 – All rights reserved

ISO/ASTM 52911-1:2019(E)
5.4 Limitations to be considered in regard to the PBF process
Certain disadvantages typically associated with AM processes shall be taken into consideration during
product design.
— Shrinkage, residual stress and deformation can occur due to local temperature differences.
— The surface quality of AM parts is typically influenced by the layer-wise build-up technique (stair-
step effect). Post-processing can be required, depending on the application.
— Consideration shall be given to deviations from form, dimensional and positional tolerances of
parts. A machining allowance shall therefore be provided for post-production finishing. Specified
geometric tolerances can be achieved by precision post-processing.
— Anisotropic characteristics typically arise due to the layer-wise build-up and shall be taken into
account during process planning.
— Not all materials available for conventional processes are currently suitable for PBF processes.
— Material properties can differ from expected values known from other technologies like forging and
casting. Material properties can be influenced significantly due to process settings and control.
— Excessive use and/or over-reliance on support structures can lead to both high material waste and
increased risk of build failure.
— Powder removal post processing is necessary.
5.5 Economic and time efficiency
Provided that the geometry permits a part to be placed in the build space in such a way that it can be
manufactured as cost-effectively as possible, various different criteria for optimization are available
depending on the number of units planned.
In the case of a one-off production, height is the factor that has the greatest impact on building time and
build costs. Parts should be orientated in such a way that the build height is kept to a minimum.
If the intention is to manufacture a larger number of units, then the build space should be used as
efficiently as possible. Parts should be orientated so as to minimize the number of build runs required.
Strategies for nesting can also be included to maximize the available build space. If the same parts are
oriented differently for best packing, i.e. results in building at different angles, then the mechanical
properties can vary from part to part.
The use of powder that remains in the system depends on the application, material and specific
requirements. Powder changes can be inefficient and time consuming. Though they are necessary
when changing material type, powders from same-material builds can be reused if permitted in
the governing specification. It is important to note, however, that recycling of powder can affect the
powder size distribution, surface characteristics and alloy composition, and this in turn affects final
part characteristics. In addition, the reusable powder characteristics and therefore recyclability can
be different for electron beam-based and laser beam-based powder bed fusion. The number of times a
powder can be recycled is dependent on the machine manufacturer and the part specification.
Many poorly designed parts (particularly those designed for conventional processes with little or no
adaptation) necessitate a specific orientation either to minimize the use of supports or to increase the
likelihood of build success. Indeed, parts designed for additive manufacture should be devised such
that build orientation is obvious and/or specified.
© ISO/ASTM International 2019 – All rights reserved 5

ISO/ASTM 52911-1:2019(E)
5.6 Feature constraints (islands, overhang, stair-step effect)
5.6.1 General
Since AM parts are built up in successive layers, separation of features can occur at some stage of the
build. This depends on the part geometry. The situations described in 5.6.2 to 5.6.4 can be regarded as
critical (the level of criticality depends on the PBF technology in focus) in this respect.
5.6.2 Islands
Islands (I) are features that connect to form a part (P) only at a later stage of the build process. How
this connection will occur shall be taken into consideration at the design stage. Parts that are stable in
terms of their overall design can be unstable during the build process (see Figure 2, left and centre).
NOTE In some circumstances, islands are not protected against mechanical damage during the powder
application process. This can lead to deformation of the islands.
Key
I islands
P part
a overhang
SOURCE VDI 3405-3:2015.
Figure 2 — Islands I (left) and overhang a (right) during the construction of part P in z-axis
5.6.3 Overhang
Areas with an overhang angle of 0° produce an overhang with length a (see Figure 2, right). Small
overhangs do not need any additional geometry in the form of support structures. In such cases, the
projecting area is self-supporting during manufacturing. The permissible values for a depend on the
specific PBF process, the material and the process parameters used. Significant overhangs can induce a
collapse or deformation of the length a of Figure 2, which can lead to the machine standstill.
5.6.4 Stair-step effect
Due to the layer-wise build-up, the 3D geometry of the part is converted into a 2,5D image before
production, with discrete steps in the build direction. The resulting error caused by deviation of this
2,5D image from the original geometry is described as the stair-step effect. The extent of this is largely
dependent on the layer thickness (see Figure 3).
6 © ISO/ASTM International 2019 – All rights reserved

ISO/ASTM 52911-1:2019(E)
SOURCE VDI 3405-3:2015.
Figure 3 — Impact of different layer thicknesses on the stair-step effect
5.7 Dimensional, form and positional accuracy
Typically, it is not possible to produce the tolerances that can be achieved with conventional tool-
based manufacturing processes. For this reason, post-processing can be necessary to meet (customer)
requirements. Post-processing may include subtractive manufacturing, surface finishing, thermal
processing, or other operations according to ISO/ASTM 52910.
In this respect, it is particularly important to be aware of and consider process parameters that
influence characteristics of the final part. For example, build orientation to some extent determines the
level of accuracy that can be achieved. Directionally dependent (anisotropic) shrinkage of the part can
occur due to the layer-wise build-up. As another example, layer-wise consistency can be affected by the
location of the part on the build platform.
5.8 Data quality, resolution, representation
The use of AM requires 3D geometric data which is typically represented as a tessellated model, but
other representations that can also be used include voxels or sliced layer representations. For tessellated
data, files describe the surface geometry of a part as a series of triangular meshes. The vertices of the
triangles are defined using the right-hand rule and the normal vector. The STL file format is recognized
as the quasi-industry data exchange format. Additional formats include AMF, which is described in
3)
ISO/ASTM 52915, and 3MF, which is being promoted by an industry consortium led by Microsoft .
In a tessellation, curved surfaces are approximated with triangles and the chosen resolution of the
tessellation determines the geometric quality of the part to be fabricated. If the resolution is too low,
the sides of the triangles defined in the STL file will be visible on the finished surface (i.e. it will appear
faceted). However, a tessellation with a resolution that is too high requires a lot of digital storage
space and is slow to transfer and handle using processing software. The resolution of a tessellation is
generally influenced by a tolerance measure, often called “chord height”, which describes the maximum
deviation of a point on the surface of the part from the triangle face. Therefore, smaller tolerance values
lead to lower deviations from the actual part surface. A typical rule of thumb is to set the tolerance to
be at least 5 times smaller than the resolution of the AM process. As a result, a chord height setting of
3) This information is given for the convenience of users of this document and does not constitute an endorsement
by ISO of the product named.
© ISO/ASTM International 2019 – All rights reserved 7

ISO/ASTM 52911-1:2019(E)
0,01 mm to 0,02 mm is recommended for most PBF processes. Other parameters can be used to set
mesh accuracy, depending on the system.
AMF supports the representation of information beyond just geometry. For example, part units
(millimetres, metres, inches), colours, materials and lattice structures are supported. STL files only
contain the tessellated geometry, while 3MF files have some of the metadata representation capabilities of
AMF. Having units incorporated into the data exchange file is very important in communicating part size.
If part geometry was imported from a 3D imaging modality, such as CT or MRI, then the data are
composed of voxels. The DICOM format is the standard used in the medical imaging industry and some
AM software tools read these files directly. Geometry resolution is controlled by the imager resolution.
6 Design guidelines for laser-based powder bed fusion of metals (PBF-LB/M)
6.1 General
6.1.1 Selecting PBF-LB/M
PBF-LB/M is a process with typical advantages and disadvantages. The technology offers opportunities
in complex design with integrated functions in one part, materials with internal structures or channels,
and/or features with undercuts or structures that cannot be realized by casting, forging or metal
cutting processes. The flexibility of PBF-LB/M offers opportunities for small series of unique products
with properties that cannot be realized with other technologies.
The advantages that occur in the use phase can be an important consideration when choosing PBF-
LB/M, even when PBF-LB/M has disadvantages in the production phase.
Important constraints can be the availability of the required materials, limited size of the part, the
approval of the technology in critical applications, the production costs and the possible need for post
processing treatments.
Some other technologies that can be applied in a similar field of application as PBF-LB/M are: PBF-EB/M,
directed energy deposition of metals, or lost model casting based upon a lost model produced by AM.
6.1.2 Design and test cycles
Part optimization can be constrained by current limits of the PBF-LB/M process. This can differ from
material to material, from machine to machine and from service provider to service provider. Often this
means that practical testing of part features can be a part of the design cycle.
6.2 Material and structural characteristics
Metals and metal alloys are the materials most commonly used for PBF-LB/M (see Annex A). Preferred
methods of production for metal powders typically include plasma or gas atomization in an argon
or nitrogen atmosphere. Because metal powders can vary significantly between suppliers, selection
should be done with care. Powder size distribution, chemistry, surface characteristics, and morphology
are just some examples of raw powder characteristics that should be considered during selection.
The successful processing of individual materials depends on a variety of factors, such as weldability,
melting temperature, thermal conductivity, melt viscosity and wetting angle (relating to the surface
[5]
tension of the melt) . These factors all affect the characteristics of the part being manufactured. For
this reason, design for PBF-LB requires taking processing environments into consideration as well.
Table A.1 shows a selection of the material classes that are available to PBF-LB/M processes. In addition
to this overview, there are some other materials that can be used such as copper alloys, gold and silver,
tungsten and tantalum. As AM technology advances, it is expected that other materials will become
available in the near future. As there are already metal powders available for processes like powder
8 © ISO/ASTM International 2019 – All rights reserved

ISO/ASTM 52911-1:2019(E)
metallurgy, metal injection moulding and cladding, it can be expected that there is a potential for use in
PBF-LB/M as well.
[6]
It is possible to achieve a relative part density close to 100 % . Figure 4 depicts a microstructure after
PBF-LB/M:
a) shows a longitudinal section (in the z–y plane) of a part made from material 1.2709 with the
overlapping tracks clearly visible;
b) shows the overlapping tracks of a single layer (x–y plane).
The microstructure created by the PBF-LB/M process is different from that observed in wrought materials,
and is heavily dependent on the processing environment, including those factors mentioned above. The
mechanical properties of the part correlates directly with the macro- and microstructure formed.
Post heat treatments of parts produced by metal AM are applied commonly for release of residual
stresses and tuning material properties.
a) Longitudinal section of a part made from material 1.2709
b) Overlapping tracks in a single layer
SOURCE VDI 3405-3:2015.
Figure 4 — Microstructure after PBF-LB/M
6.3 Support structures
The PBF-LB/M process requires the part to be securely connected to the build plate. The connections
can be made either directly (build directly on build platform) or by means of support structures.
Support structures in PBF-LB/M processes serve multiple functions, including
— dissipation of heat,
— securing the part to the build platform,
© ISO/ASTM International 2019 – All rights reserved 9

ISO/ASTM 52911-1:2019(E)
— compensating for residual stress-induced warping, and
— as a provisional support for a piece under construction.
While support structures are common in many AM processes, specific guidance on their application is
process dependent. Table 2 provides guidance on the use of support structures in PBF-LB/M processes.
The values used in Table 2 are general guidelines, and both process parameters and material specifics
affect the governing values.
Because support structures are so important when designing for AM, the designer should decide at an
early stage about the build orientation of the part for the particular PBF-LB/M machine and should be
aware of the central elements of the process chain needed for manufacturing. The effect of the support
design can therefore be taken into account when several design decisions are available. For instance,
a design configuration can lead to an increase in build time but can also sign
...

SLOVENSKI STANDARD
01-december-2019
Dodajalna izdelava - Konstruiranje - 1. del: Spajanje kovinskega prahu na podlagi z
laserskim žarkom (ISO/ASTM 52911-1:2019)
Additive manufacturing - Design - Part 1: Laser-based powder bed fusion of metals
(ISO/ASTM 52911-1:2019)
Additive Fertigung - Technische Konstruktionsrichtlinie für Pulverbettfusion - Teil 1:
Laserbasierte Pulverbettfusion von Metallen (ISO/ASTM 52911-1:2019)
Fabrication additive - Conception - Partie 1: Fusion laser sur lit de poudre métallique
(ISO/ASTM 52911-1:2019)
Ta slovenski standard je istoveten z: EN ISO/ASTM 52911-1:2019
ICS:
25.030 3D-tiskanje Additive manufacturing
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO/ASTM 52911-1
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2019
EUROPÄISCHE NORM
ICS 25.030
English Version
Additive manufacturing - Design - Part 1: Laser-based
powder bed fusion of metals (ISO/ASTM 52911-1:2019)
Fabrication additive - Conception - Partie 1: Fusion Additive Fertigung - Konstruktion - Teil 1:
laser sur lit de poudre métallique (ISO/ASTM 52911- Laserbasierte Pulverbettfusion von Metallen
1:2019) (ISO/ASTM 52911-1:2019)
This European Standard was approved by CEN on 21 July 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO/ASTM 52911-1:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO/ASTM 52911-1:2019) has been prepared by Technical Committee ISO/TC 261
"Additive manufacturing" in collaboration with Technical Committee CEN/TC 438 “Additive
Manufacturing” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2020, and conflicting national standards shall
be withdrawn at the latest by March 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO/ASTM 52911-1:2019 has been approved by CEN as EN ISO/ASTM 52911-1:2019
without any modification.
INTERNATIONAL ISO/ASTM
STANDARD 52911-1
First edition
2019-07
Additive manufacturing — Design —
Part 1:
Laser-based powder bed fusion of
metals
Fabrication additive — Conception —
Partie 1: Fusion laser sur lit de poudre métallique
Reference number
ISO/ASTM 52911-1:2019(E)
©
ISO/ASTM International 2019
ISO/ASTM 52911-1:2019(E)
© ISO/ASTM International 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be
reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester. In the United States, such requests should be sent to ASTM International.
ISO copyright office ASTM International
CP 401 • Ch. de Blandonnet 8 100 Barr Harbor Drive, PO Box C700
CH-1214 Vernier, Geneva West Conshohocken, PA 19428-2959, USA
Phone: [phone] Phone: [phone]
Fax: [phone] Fax: [phone]
Email: [e-mail] Email: [e-mail]
Website: www.iso.org Website: www.astm.org
Published in Switzerland
ii © ISO/ASTM International 2019 – All rights reserved

ISO/ASTM 52911-1:2019(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
4.1 Symbols . 2
4.2 Abbreviated terms . 3
5 Characteristics of powder bed fusion (PBF) processes . 3
5.1 General . 3
5.2 Size of the parts . 4
5.3 Benefits to be considered in regard to the PBF process . 4
5.4 Limitations to be considered in regard to the PBF process . 5
5.5 Economic and time efficiency . 5
5.6 Feature constraints (islands, overhang, stair-step effect) . 6
5.6.1 General. 6
5.6.2 Islands . 6
5.6.3 Overhang . 6
5.6.4 Stair-step effect . 6
5.7 Dimensional, form and positional accuracy . 7
5.8 Data quality, resolution, representation . 7
6 Design guidelines for laser-based powder bed fusion of metals (PBF-LB/M) .8
6.1 General . 8
6.1.1 Selecting PBF-LB/M . 8
6.1.2 Design and test cycles . 8
6.2 Material and structural characteristics . 8
6.3 Support structures . 9
6.4 Build orientation, positioning and arrangement .11
6.4.1 General.11
6.4.2 Powder spreading .11
6.4.3 Support structures design .12
6.4.4 Curl effect .13
6.5 Anisotropy of the material characteristics.14
6.6 Surface roughness .14
6.7 Post-production finishing .14
6.7.1 General.14
6.7.2 Surface finishing .15
6.7.3 Removal of powder residue .15
6.7.4 Removal of support structures .15
6.7.5 Adjusting geometric tolerances .15
6.7.6 Heat treatment.15
6.8 Design considerations.16
6.8.1 General.16
6.8.2 Cavities .16
6.8.3 Gaps .16
6.8.4 Wall thicknesses .16
6.8.5 Holes and channels .17
6.8.6 Integrated markings .17
6.9 Example applications .17
6.9.1 General.17
6.9.2 Integral design (provided by CETIM — Technical Centre for Mechanical
Industry) .17
© ISO/ASTM International 2019 – All rights reserved iii

ISO/ASTM 52911-1:2019(E)
6.9.3 Gear wheel design (provided by Fraunhofer IGCV) .19
6.9.4 Impossible crossing (provided by TNO — The Netherlands Organisation
for applied scientific research) .20
Annex A (informative) Materials for PBF-LB/M .22
Bibliography .23
iv © ISO/ASTM International 2019 – All rights reserved

ISO/ASTM 52911-1:2019(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 261, Additive manufacturing, in
cooperation with ASTM F42, Additive Manufacturing Technologies, on the basis of a partnership
agreement between ISO and ASTM International with the aim to create a common set of ISO/ASTM
standards on additive manufacturing.
A list of all parts in the ISO 52911 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
© ISO/ASTM International 2019 – All rights reserved v

ISO/ASTM 52911-1:2019(E)
Introduction
Laser-based powder bed fusion of metals (PBF-LB/M) describes an additive manufacturing (AM)
process and offers an additional manufacturing option alongside established processes. PBF-LB/M has
the potential to reduce manufacturing time and costs, and increase part functionality. Practitioners
are aware of the strengths and weaknesses of conventional, long-established manufacturing processes,
such as cutting, joining and shaping processes (e.g. by machining, welding or injection moulding), and
of giving them appropriate consideration at the design stage and when selecting the manufacturing
process. In the case of PBF-LB/M and AM in general, design and manufacturing engineers only have
a limited pool of experience. Without the limitations associated with conventional processes, the
use of PBF-LB/M offers designers and manufacturers a high degree of freedom and this requires an
understanding about the possibilities and limitations of the process.
The ISO 52911 series provides guidance for different powder bed fusion (PBF) technologies. It is
1)
intended that the series will include this document on PBF-LB/M, ISO 52911-2 on laser-based powder
2)
bed fusion of polymers (PBF-LB/P), and ISO 52911-3 on electron beam powder bed fusion of metals
(PBF-EB/M). Each document in the series shares Clauses 1 to 5, where general information including
terminology and the PBF process is provided. The subsequent clauses focus on the specific technology.
This document is based on VDI 3405-3:2015. It provides support to technology users, such as design
and production engineers, when designing parts that need to be manufactured by means of PBF-LB/M.
It will help practitioners to explore the benefits of PBF-LB/M and to recognize the process-related
limitations when designing parts. It also builds on ISO/ASTM 52910 to extend the requirements,
guidelines and recommendations for AM design to include the PBF process.
1) Under preparation.
2) Under preparation.
vi © ISO/ASTM International 2019 – All rights reserved

INTERNATIONAL STANDARD ISO/ASTM 52911-1:2019(E)
Additive manufacturing — Design —
Part 1:
Laser-based powder bed fusion of metals
1 Scope
This document specifies the features of laser-based powder bed fusion of metals (PBF-LB/M) and
provides detailed design recommendations.
Some of the fundamental principles are also applicable to other additive manufacturing (AM) processes,
provided that due consideration is given to process-specific features.
This document also provides a state of the art review of design guidelines associated with the use of
powder bed fusion (PBF) by bringing together relevant knowledge about this process and by extending
the scope of ISO/ASTM 52910.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/ASTM 52900, Additive manufacturing — General principles — Fundamentals and vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/ASTM 52900 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
curl effect
thermal and residual stress effect
dimensional distortion as the printed part cools and solidifies after
being built or by poorly evacuated heat input
3.2
downskin area
D

(sub-)area where the normal vector n projection on the z-axis is negative
Note 1 to entry: See Figure 1.
© ISO/ASTM International 2019 – All rights reserved 1

ISO/ASTM 52911-1:2019(E)
3.3
downskin angle
δ
angle between the plane of the build platform and the downskin area (3.2) where the value lies between
0° (parallel to the build platform) and 90° (perpendicular to the build platform)
Note 1 to entry: See Figure 1.
3.4
upskin area
U

(sub-)area where the normal vector n projection on the z-axis is positive
Note 1 to entry: See Figure 1.
3.5
upskin angle
υ
angle between the plane of the build platform and the upskin area (3.4) where the value lies between 0°
(parallel to the build platform) and 90° (perpendicular to the build platform)
Note 1 to entry: See Figure 1.
Key
δ downskin angle

normal vector
n
D downskin (left) area
U upskin (right) area
υ upskin angle
SOURCE VDI 3405-3:2015.
Figure 1 — Orientation of the part surfaces relating to the build platform
4 Symbols and abbreviated terms
4.1 Symbols
The symbols given in Table 1 are used in this document.
2 © ISO/ASTM International 2019 – All rights reserved

ISO/ASTM 52911-1:2019(E)
Table 1 — Symbols
Symbol Designation Unit
a overhang mm
D downskin area mm
I island mm

normal vector —
n
R mean roughness µm
a
R average surface roughness µm
z
U upskin area mm
δ downskin angle °
υ upskin angle °
4.2 Abbreviated terms
The following abbreviated terms are used in this document.
AM additive manufacturing
AMF additive manufacturing file format
CT computed tomography
DICOM digital imaging and communications in medicine
HIP hot isostatic pressing
MRI magnetic resonance imaging
PBF powder bed fusion
PBF-EB/M electron beam powder bed fusion of metals
PBF-LB laser-based powder bed fusion
PBF-LB/M laser-based powder bed fusion of metals (also known as, for example, laser beam melting,
selective laser melting)
PBF-LB/P laser-based powder bed fusion of polymers (also known as, for example, laser beam
melting, selective laser melting)
STL stereolithography format or surface tessellation language
5 Characteristics of powder bed fusion (PBF) processes
5.1 General
Consideration shall be given to the specific characteristics of the manufacturing process used in order
to optimize the design of a part. Examples of the features of AM processes which need to be taken into
consideration during the design and process planning stages are listed in 5.2 to 5.8. With regards to
metal processing, a distinction can be made between, for example, laser-based PBF (applied for metals
and polymers) and electron beam-based PBF (applied for metals only).
Polymers PBF uses, in almost every case, low-power lasers to sinter polymer powders together. As with
polymer powders PBF, metals PBF includes varying processing techniques. Unlike polymers, metals
PBF often requires the addition of support structures (see 6.4.3). Metals PBF processes may use low-
© ISO/ASTM International 2019 – All rights reserved 3

ISO/ASTM 52911-1:2019(E)
power lasers to bind powder particles by only melting the surface of the powder particles or high-power
(approximately 200 W to 1 kW) beams to fully melt and fuse the powder particles together.
Electron beam-based melting and laser-based melting have similar capabilities, although the beam
energy transferred from the electron beam to the metal is of a higher intensity and the process
most commonly operates at higher temperatures than the laser counterpart, therefore typically also
supporting faster build rates at lower resolutions. In general, since the powder bed is preheated and
kept close to the melting temperature during the building operation, electron beam processes subject
parts to less thermal induced stresses and have faster build rates, but the trade-off often comes with
much longer times needed for the build chamber to cool down after the build cycle has been completed,
and in general larger minimum feature sizes and greater surface roughness than laser melting.
5.2 Size of the parts
The size of the parts is not only limited by the working area/working volume of the PBF-machine. Also,
the occurrence of cracks and deformation due to residual stresses can limit the maximum part size.
Another important practical factor that can limit the maximum part size is the cost of production having
a direct relation to the size and volume of the part. Cost of production can be minimized by choosing
part location and build orientation in a way that allows nesting of as many parts as possible. The cost of
the volume of powder required to fill the bed should be considered. Powder reuse rules impact this cost
significantly. If no reuse is allowed then all powder is scrapped regardless of volume solidified.
5.3 Benefits to be considered in regard to the PBF process
PBF processes can be advantageous for manufacturing parts where the following points are relevant.
— Integration of multiple functions in the same part.
— Parts can be manufactured to near-net shape (i.e. close to the finished shape and size).
— Degrees of design freedom for parts are typically high. Limitations of conventional manufacturing
processes do not usually exist, e.g. for:
— tool accessibility, and
— undercuts.
— A wide range of complex geometries can be produced, such as:
— free-form geometries, e.g. organic structures,
— topologically optimized structures, in order to reduce mass and optimize mechanical
properties, and
— infill structures, e.g. honeycomb.
— The degree of part complexity is largely unrelated to production costs, unlike most conventional
manufacturing.
— Assembly and joining processes can be reduced through part consolidation, potentially achieving
en bloc construction.
— Overall part characteristics can be selectively configured by adjusting process parameters locally.
— Reduction in lead times from design to part production.
4 © ISO/ASTM International 2019 – All rights reserved

ISO/ASTM 52911-1:2019(E)
5.4 Limitations to be considered in regard to the PBF process
Certain disadvantages typically associated with AM processes shall be taken into consideration during
product design.
— Shrinkage, residual stress and deformation can occur due to local temperature differences.
— The surface quality of AM parts is typically influenced by the layer-wise build-up technique (stair-
step effect). Post-processing can be required, depending on the application.
— Consideration shall be given to deviations from form, dimensional and positional tolerances of
parts. A machining allowance shall therefore be provided for post-production finishing. Specified
geometric tolerances can be achieved by precision post-processing.
— Anisotropic characteristics typically arise due to the layer-wise build-up and shall be taken into
account during process planning.
— Not all materials available for conventional processes are currently suitable for PBF processes.
— Material properties can differ from expected values known from other technologies like forging and
casting. Material properties can be influenced significantly due to process settings and control.
— Excessive use and/or over-reliance on support structures can lead to both high material waste and
increased risk of build failure.
— Powder removal post processing is necessary.
5.5 Economic and time efficiency
Provided that the geometry permits a part to be placed in the build space in such a way that it can be
manufactured as cost-effectively as possible, various different criteria for optimization are available
depending on the number of units planned.
In the case of a one-off production, height is the factor that has the greatest impact on building time and
build costs. Parts should be orientated in such a way that the build height is kept to a minimum.
If the intention is to manufacture a larger number of units, then the build space should be used as
efficiently as possible. Parts should be orientated so as to minimize the number of build runs required.
Strategies for nesting can also be included to maximize the available build space. If the same parts are
oriented differently for best packing, i.e. results in building at different angles, then the mechanical
properties can vary from part to part.
The use of powder that remains in the system depends on the application, material and specific
requirements. Powder changes can be inefficient and time consuming. Though they are necessary
when changing material type, powders from same-material builds can be reused if permitted in
the governing specification. It is important to note, however, that recycling of powder can affect the
powder size distribution, surface characteristics and alloy composition, and this in turn affects final
part characteristics. In addition, the reusable powder characteristics and therefore recyclability can
be different for electron beam-based and laser beam-based powder bed fusion. The number of times a
powder can be recycled is dependent on the machine manufacturer and the part specification.
Many poorly designed parts (particularly those designed for conventional processes with little or no
adaptation) necessitate a specific orientation either to minimize the use of supports or to increase the
likelihood of build success. Indeed, parts designed for additive manufacture should be devised such
that build orientation is obvious and/or specified.
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ISO/ASTM 52911-1:2019(E)
5.6 Feature constraints (islands, overhang, stair-step effect)
5.6.1 General
Since AM parts are built up in successive layers, separation of features can occur at some stage of the
build. This depends on the part geometry. The situations described in 5.6.2 to 5.6.4 can be regarded as
critical (the level of criticality depends on the PBF technology in focus) in this respect.
5.6.2 Islands
Islands (I) are features that connect to form a part (P) only at a later stage of the build process. How
this connection will occur shall be taken into consideration at the design stage. Parts that are stable in
terms of their overall design can be unstable during the build process (see Figure 2, left and centre).
NOTE In some circumstances, islands are not protected against mechanical damage during the powder
application process. This can lead to deformation of the islands.
Key
I islands
P part
a overhang
SOURCE VDI 3405-3:2015.
Figure 2 — Islands I (left) and overhang a (right) during the construction of part P in z-axis
5.6.3 Overhang
Areas with an overhang angle of 0° produce an overhang with length a (see Figure 2, right). Small
overhangs do not need any additional geometry in the form of support structures. In such cases, the
projecting area is self-supporting during manufacturing. The permissible values for a depend on the
specific PBF process, the material and the process parameters used. Significant overhangs can induce a
collapse or deformation of the length a of Figure 2, which can lead to the machine standstill.
5.6.4 Stair-step effect
Due to the layer-wise build-up, the 3D geometry of the part is converted into a 2,5D image before
production, with discrete steps in the build direction. The resulting error caused by deviation of this
2,5D image from the original geometry is described as the stair-step effect. The extent of this is largely
dependent on the layer thickness (see Figure 3).
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ISO/ASTM 52911-1:2019(E)
SOURCE VDI 3405-3:2015.
Figure 3 — Impact of different layer thicknesses on the stair-step effect
5.7 Dimensional, form and positional accuracy
Typically, it is not possible to produce the tolerances that can be achieved with conventional tool-
based manufacturing processes. For this reason, post-processing can be necessary to meet (customer)
requirements. Post-processing may include subtractive manufacturing, surface finishing, thermal
processing, or other operations according to ISO/ASTM 52910.
In this respect, it is particularly important to be aware of and consider process parameters that
influence characteristics of the final part. For example, build orientation to some extent determines the
level of accuracy that can be achieved. Directionally dependent (anisotropic) shrinkage of the part can
occur due to the layer-wise build-up. As another example, layer-wise consistency can be affected by the
location of the part on the build platform.
5.8 Data quality, resolution, representation
The use of AM requires 3D geometric data which is typically represented as a tessellated model, but
other representations that can also be used include voxels or sliced layer representations. For tessellated
data, files describe the surface geometry of a part as a series of triangular meshes. The vertices of the
triangles are defined using the right-hand rule and the normal vector. The STL file format is recognized
as the quasi-industry data exchange format. Additional formats include AMF, which is described in
3)
ISO/ASTM 52915, and 3MF, which is being promoted by an industry consortium led by Microsoft .
In a tessellation, curved surfaces are approximated with triangles and the chosen resolution of the
tessellation determines the geometric quality of the part to be fabricated. If the resolution is too low,
the sides of the triangles defined in the STL file will be visible on the finished surface (i.e. it will appear
faceted). However, a tessellation with a resolution that is too high requires a lot of digital storage
space and is slow to transfer and handle using processing software. The resolution of a tessellation is
generally influenced by a tolerance measure, often called “chord height”, which describes the maximum
deviation of a point on the surface of the part from the triangle face. Therefore, smaller tolerance values
lead to lower deviations from the actual part surface. A typical rule of thumb is to set the tolerance to
be at least 5 times smaller than the resolution of the AM process. As a result, a chord height setting of
3) This information is given for the convenience of users of this document and does not constitute an endorsement
by ISO of the product named.
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ISO/ASTM 52911-1:2019(E)
0,01 mm to 0,02 mm is recommended for most PBF processes. Other parameters can be used to set
mesh accuracy, depending on the system.
AMF supports the representation of information beyond just geometry. For example, part units
(millimetres, metres, inches), colours, materials and lattice structures are supported. STL files only
contain the tessellated geometry, while 3MF files have some of the metadata representation capabilities of
AMF. Having units incorporated into the data exchange file is very important in communicating part size.
If part geometry was imported from a 3D imaging modality, such as CT or MRI, then the data are
composed of voxels. The DICOM format is the standard used in the medical imaging industry and some
AM software tools read these files directly. Geometry resolution is controlled by the imager resolution.
6 Design guidelines for laser-based powder bed fusion of metals (PBF-LB/M)
6.1 General
6.1.1 Selecting PBF-LB/M
PBF-LB/M is a process with typical advantages and disadvantages. The technology offers opportunities
in complex design with integrated functions in one part, materials with internal structures or channels,
and/or features with undercuts or structures that cannot be realized by casting, forging or metal
cutting processes. The flexibility of PBF-LB/M offers opportunities for small series of unique products
with properties that cannot be realized with other technologies.
The advantages that occur in the use phase can be an important consideration when choosing PBF-
LB/M, even when PBF-LB/M has disadvantages in the production phase.
Important constraints can be the availability of the required materials, limited size of the part, the
approval of the technology in critical applications, the production costs and the possible need for post
processing treatments.
Some other technologies that can be applied in a similar field of application as PBF-LB/M are: PBF-EB/M,
directed energy deposition of metals, or lost model casting based upon a lost model produced by AM.
6.1.2 Design and test cycles
Part optimization can be constrained by current limits of the PBF-LB/M process. This can differ from
material to material, from machine to machine and from service provider to service provider. Often this
means that practical testing of part features can be a part of the design cycle.
6.2 Material and structural characteristics
Metals and metal alloys are the materials most commonly used for PBF-LB/M (see Annex A). Preferred
methods of production for metal powders typically include plasma or gas atomization in an argon
or nitrogen atmosphere. Because metal powders can vary significantly between suppliers, selection
should be done with care. Powder size distribution, chemistry, surface characteristics, and morphology
are just some examples of raw powder characteristics that should be considered during selection.
The successful processing of individual materials depends on a variety of factors, such as weldability,
melting temperature, thermal conductivity, melt viscosity and wetting angle (relating to the surface
[5]
tension of the melt) . These factors all affect the characteristics of the part being manufactured. For
this reason, design for PBF-LB requires taking processing environments into consideration as well.
Table A.1 shows a selection of the material classes that are available to PBF-LB/M processes. In addition
to this overview, there are some other materials that can be used such as copper alloys, gold and silver,
tungsten and tantalum. As AM technology advances, it is expected that other materials will become
available in the near future. As there are already metal powders available for processes like powder
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ISO/ASTM 52911-1:2019(E)
metallurgy, metal injection moulding and cladding, it can be expected that there is a potential for use in
PBF-LB/M as well.
[6]
It is possible to achieve a relative part density close to 100 % . Figure 4 depicts a microstructure after
PBF-LB/M:
a) shows a longitudinal section (in the z–y plane) of a part made from material 1.2709 with the
overlapping tracks clearly visible;
b) shows the overlapping tracks of a single layer (x–y plane).
The microstructure created by the PBF-LB/M process is different from that observed in wrought materials,
and is heavily dependent on the processing environment, including those factors mentioned above. The
mechanical properties of the part correlates directly with the macro- and microstructure formed.
Post heat treatments of parts produced by metal AM are applied commonly for release of residual
stresses and tuning material properties.
a) Longitudinal section of a part made from material 1.2709
b) Overlapping tracks in a single layer
SOURCE VDI 3405-3:2015.
Figure 4 — Microstructure after PBF-LB/M
6.3 Support structures
The PBF-LB/M process requires the part to be securely connected to the build plate. The connections
can be made either directly (build directly on build platform) or by means of support structures.
Support structures in PBF-LB/M processes serve multiple functions, including
— dissipation of heat,
— securing the part to the build platform,
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ISO/ASTM 52911-1:2019(E)
— compensating for residual stress-induced warping, and
— as a provisional support for a piece under construction.
While support structures are common in many AM processes, specific guidance on their application is
process dependent. Table 2 provides guidance on the use of support structures in PBF-LB/M processes.
The values used in Table 2 are general guidelines, and both process parameters and material specifics
affect the governing values.
Because support structures are so important when designing for AM, the designer should decide at an
early stage about the build orientation of the part for the particular PBF-LB/M machine and should be
aware of the central elements of the process chain needed for manufacturing. The effect of the support
design can therefore be taken into account when several design decisions are available. For instance,
a design configuration can lead to an increase in build time but can also s
...