prEN ISO/ASTM 52911-3

Additive Manufacturing - Design - Part 3: Electron beam powder bed fusion of metals (ISO/ASTM 52911-3:2021)

This document specifies the features of electron beam powder bed fusion of metals (EB-PBF-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 3: Pulverbettbasiertes Schmelzen von Metallen mittels Elektronenstrahl (ISO/ASTM DIS 52911-3:2021)

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

Fabrication additive - Conception - Partie 3: Fusion par faisceau d'électrons sur lit de poudre métallique (ISO/ASTM 52911-3:2021)

[Not translated]

General Information

• Status: Not Published
• ICS: 25.030 - Additive manufacturing
• Technical Committee: CEN/TC 438 - Additive Manufacturing
• Drafting Committee: CEN/TC 438 - Additive Manufacturing
• Ref Project: oSIST prEN ISO/ASTM 52911-3:2022 - Additive Manufacturing - Design - Part 3: Electron beam powder bed fusion of metals (ISO/ASTM 52911-3:2021)

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN ISO/ASTM 52911-3:2022
01-februar-2022
[Not translated]

Additive Manufacturing - Design - Part 3: Electron beam powder bed fusion of metals

(ISO/ASTM 52911-3:2021)
Additive Manufacturing - Konstruktion - Teil 3: Standardrichtlinie für das

pulverbettbasierte Elektronenstrahlschmelzen von Metallen (ISO/ASTM 52911-3:2021)

Fabrication additive - Conception - Partie 3: Fusion par faisceau d'électrons sur lit de

poudre métallique (ISO/ASTM 52911-3:2021)
Ta slovenski standard je istoveten z: prEN ISO/ASTM 52911-3
ICS:
25.030 3D-tiskanje Additive manufacturing
oSIST prEN ISO/ASTM 52911-3:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO/ASTM 52911-3:2022
DRAFT INTERNATIONAL STANDARD
ISO/ASTM DIS 52911-3
ISO/TC 261 Secretariat: DIN
Voting begins on: Voting terminates on:
2021-12-13 2022-03-07
Additive Manufacturing — Design —
Part 3:
Electron beam powder bed fusion of metals
Fabrication additive - Conception —
Partie 3: Fusion par faisceau d'électrons sur lit de poudre métallique
ICS: 25.030
This document is circulated as received from the committee secretariat.
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
ISO/CEN PARALLEL PROCESSING
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/ASTM DIS 52911-3:2021(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. © ISO/ASTM International 2021
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oSIST prEN ISO/ASTM 52911-3:2022
ISO/ASTM DIS 52911-3:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/ASTM International 2021

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

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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 ........................................................................... 4

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 electron beam powder bed fusion of metals (PBF-EB/M) ............................8

6.1 General ........................................................................................................................................................................................................... 8

6.1.1 Selecting PBF-EB/M ......................................................................................................................................................... 8

6.1.2 Design and test cycles .................................................................................................................................................... 8

6.2 Material and structural characteristics ........................................................................................................................... 8

6.3 Build orientation, positioning and arrangement ..................................................................................................... 9

6.3.1 General ........................................................................................................................................................................................ 9

6.3.2 Powder spreading .............................................................................................................................................................. 9

6.3.3 Support structures design ...................................................................................................................................... 10

6.3.4 Part nesting ..........................................................................................................................................................................12

6.3.5 Build plate part design considerations........................................................................................................ 13

6.3.6 Curl effect ............................................................................................................................................................................... 13

6.3.7 Melt parameters ............................................................................................................................................................... 14

6.4 Anisotropy/heterogeneity of the material and part characteristics ..................................................15

6.4.1 General .....................................................................................................................................................................................15

6.4.2 Grain morphology .......................................................................................................................................................... 15

6.4.3 Porosity ........................................................................................................................................... .........................................15

6.4.4 Intermetallic diffusion layer ................................................................................................................................. 16

6.4.5 Chemistry heterogeneity ......................................................................................................................................... 16

6.4.6 Thermal history ............................................................................................................................................................... 16

6.5 Surfaces ...................................................................................................................................................................................................... 17

6.6 Post-production finishing .......................................................................................................................................................... 17

6.6.1 General ..................................................................................................................................................................................... 17

6.6.2 Surface finishing .............................................................................................................................................................. 17

6.6.3 Removal of powder residue ................................................................................................................................... 17

6.6.4 Removal of support structures........................................................................................................................... 17

6.6.5 Geometric tolerances................................................................................................................................................... 18

6.6.6 Heat treatment .................................................................................................................................................................. 18

6.7 Design considerations ................................................................................................................................................................... 18

6.7.1 General ..................................................................................................................................................................................... 18

6.7.2 Cavities ..................................................................................................................................................................................... 18

iii
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6.7.3 Gaps ............................................................................................................................................................................................. 19

6.7.4 Wall thicknesses .............................................................................................................................................................. 19

6.7.5 Holes and channels ........................................................................................................................................................ 19

6.7.6 Integrated markings .................................................................................................................................................... 19

6.8 Example applications .....................................................................................................................................................................20

6.8.1 Topology Optimized Bracket Printed using Stacking Build Layout

(provided by GE Arcam) ........................................................................................................................................... 20

6.8.2 Acetabular cup stacking design (provided by LimaCorporate Spa) .................................. 21

6.8.3 Optimized elbow implant design (provided by LimaCorporate Spa) ...............................23

6.8.4 Lightweight pipe design (provided by JEOL) ......................................................................................... 23

Bibliography .............................................................................................................................................................................................................................25

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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 Committee 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 2021 – All rights reserved
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Introduction

Powder bed fusion of metals (PBF/M) is an additive manufacturing (AM) process that offers additional

manufacturing options alongside other established AM processes. PBF/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/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/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. In addition

to this document on PBF-EB/M, the series is made up of ISO 52911-1 on laser-based powder bed fusion

of metals (PBF-LB/M) and ISO 52911-2 on laser-based powder bed fusion of polymers (PBF-LB/P). 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 provides support to technology users, such as design and production engineers, when

designing parts that need to be manufactured by means of PBF-EB/M. It will help practitioners to

explore the benefits of PBF-EB/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.
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oSIST prEN ISO/ASTM 52911-3:2022
DRAFT INTERNATIONAL STANDARD ISO/ASTM DIS 52911-3:2021(E)
Additive Manufacturing — Design —
Part 3:
Electron beam powder bed fusion of metals
1 Scope

This document specifies the features of electron beam powder bed fusion of metals (PBF-EB/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

ISO 17296-2, Additive manufacturing — General principles — Part 2: Overview of process categories and

feedstock

ISO/ASTM 52915, Specification for additive manufacturing file format (AMF) Version 1.2

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:

— IEC Electropedia: available at https:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1
curl effect
thermal and residual stress effect

dimensional distortion as the melted material cools and solidifies

after being built or by poorly evacuated heat input
3.2
downskin area
(sub-)area where the normal vector n projection on the z-axis is negative
Note 1 to entry: See Figure 1.
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3.3
downskin angle

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
(sub-)area where the normal vector n in relation to z-axis is positive
Note 1 to entry: See Figure 1.
3.5
upskin angle

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.
[1]
Note 2 to entry: Source: VDI 3405 Part 3:2015 .
Key
δ downskin angles U Upskin (right) areas
normal vector υ Upskin angles
D downskin (left) areas Z_ build direction
[1]
Note 1 to entry Source: VDI 3405 Part 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.
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Table 1 — Symbols
Symbol Designation Unit
a overhang mm
D downskin area mm
I island mm
normal vector —
U upskin area mm
δ downskin angle °
υ upskin angle °
4.2 Abbreviated terms
The following abbreviated terms are used in this document.
CT computed tomography
DICOM digital imaging and communications in medicine
PBF-EB/M electron beam powder bed fusion of metals
HIP hot isostatic pressing
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)
MRI magnetic resonance imaging
5 Characteristics of powder bed fusion (PBF) processes
5.1 General

Consideration should 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. Electron

beam powder bed fusion for polymers is not usually considered because the negative charge from the

electron beam will accumulate in non-conductive polymer powder and cause repulsive events that

will ruin powder layer continuity and make any controlled sintering or melting impossible. As with

polymer powders PBF, metals PBF includes varying processing techniques. Like polymers, metals PBF

often requires the addition of support structures (see 6.3.3). Metals PBF processes may use low-power

lasers to bind powder particles by only melting the surface of the powder particles or high-power

(approximately 200 W to 1 kW) energy beams to fully melt and fuse the powder particles together.

PBF-EB/M and PBF-LB/M have similar capabilities, although differences between these processes leads,

in general, to PBF-EB/M supporting faster build rates at lower feature resolution compared to PBF-

LB/M. The beam energy from the electron beam is of a higher intensity (due to a high energy source

3 to 6 kW), and the mechanism to raster the beam (i.e. electromagnetics for PBF-EB/M, optics for PBF-

LB/M) differs between the two types of PBF processes. PBF-EB/M also tends to utilize a larger beam

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spot size, larger powder size distribution, and larger layer thickness. In general, PBF-EB/M subjects

parts to less thermal stresses (as powder layers are preheated before melting) and have faster build

rates, but the trade-off often comes with general greater minimum feature sizes and greater surface

roughness compared to PBF-LB/M.
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 maximal part

size. Another important practical factor that can limit the maximal 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.

Also, the volume of powder needed to fill the bed to required volume (part depth x bed area) may be

a consideration. Powder reuse protocols 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 higher. Limitations of conventional manufacturing

processes do not usually exist, e.g. for
— tool accessibility, and
— machining undercuts.
— A wide range of complex geometries can be produced, such as
— free-form geometries, e.g. organic structures,

— topologically optimised structures, in order to reduce mass and optimize mechanical properties,

— infill structures, e.g. honeycomb, and

— porous lattice structure on surface of otherwise solid component, e.g. osteosynthesis structures

in medical device industry.

— 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.
5.4 Limitations to be considered in regard to the PBF process

Certain disadvantages typically associated with AM processes should be taken into consideration

during product design.

— Shrinkage, residual stress and deformation can occur due to temperature differences. Preheating

of the powder bed (which is the normal procedure in PBF-EB/M) can be used to minimize these

effects.
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— The surface quality of AM parts is typically influenced by the layer-wise build-up technique (stair-

step effect) and utilized powder size distribution. Post-processing may be required, depending on

the application.

— Consideration should be given to deviations from form, dimensional and positional tolerances of

parts. A machining allowance should therefore be provided for post-production finishing. Specified

geometric tolerances can be achieved by precision post-processing operations.

— Anisotropic characteristics typically arise due to the layer-wise build-up and should 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.

— Unmelted powder removal after processing is necessary, and for PBF-EB/M this powder is often

lig
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