Additive manufacturing - Design - Part 2: Laser-based powder bed fusion of polymers (ISO/ASTM 52911-2:2019)

This document specifies the features of laser-based powder bed fusion of polymers (LB-PBF/P) 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 2: Laserbasierte Pulverbettfusion von Polymeren (ISO/ASTM 52911-2:2019)

Dieses Dokument legt die Merkmale der laserbasierten Pulverbettfusion von Polymeren (LB PBF P) 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 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 2: Fusion laser sur lit de poudre polymère (ISO/ASTM 52911-2:2019)

Le présent document spécifie les caractéristiques de la fusion laser sur lit de poudre polymère (LB-PBF/P) et fournit des recommandations détaillées de conception.
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.

Aditivna proizvodnja - Konstruiranje - 2. del: Selektivno lasersko sintranje polimerov (ISO/ASTM 52911-2:2019)

Ta standard podaja priporočila za izbiro materiala, zahteve za proizvodnjo in izdelavo, preskušanje in kvalifikacijo jeklenih struktur ter sestavnih delov za obrate za predelavo nafte in zemeljskega plina na morju in kopnem, ki delujejo v arktičnem okolju ter drugih hladnih okoljih. Ta dokument se uporablja kot dodatek k obstoječim standardom za jeklene strukture, za katere določeni obratovalni pogoji na arktičnem območju niso zadovoljivo obravnavani. Ta dokument podaja določene zahteve, ki zagotavljajo varno delovanje v zvezi z nevarnostjo lomov pri nizkih temperaturah. Te zahteve vplivajo na izbiro kakovostnega razreda materiala in razreda načrtovanja ter na tehnične dobavne pogoje za jeklo. Prav tako vplivajo na zahteve glede izdelave ter preskušanja in kvalifikacije. V tem dokumentu so tudi podana priporočila: – za ublažitev operacijskih in integracijskih vidikov, povezanih s kopičenjem snega in ledu na palubnih konstrukcijah; – za upoštevanje določenih obratovalnih pogojev v arktičnem območju pri ocenjevanju korozije in zahtev za korozijske zaščitne sisteme; – za določene obratovalne zahteve, ki zagotavljajo varno obratovanje v arktičnih območjih. Zahteve v tem dokumentu se uporabljajo pri vseh obratovalnih temperaturah, vendar posamezne zahteve, ki so povezane z zmanjšano zmogljivostjo (izguba moči) pri visokih temperaturah, niso obravnavane. Obstajajo lahko omejitve za ustrezne najnižje načrtovane temperature, ki jih povzroči zmožnost učinkovitosti materiala pri nizki temperaturi, vendar te omejitve ne predstavljajo omejitev za področje uporabe tega dokumenta. Za namene praktične uporabe tega dokumenta so nizke temperature opredeljene kot najnižje pričakovane temperature med obratovanjem (LAST) pod –10 °C.

General Information

Status
Withdrawn
Publication Date
30-Jan-2020
Withdrawal Date
29-Apr-2020
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Start Date
23-Oct-2019
Completion Date
23-Oct-2019

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Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO/ASTM 52911-2:2020
01-januar-2020
Aditivna proizvodnja - Konstruiranje - 2. del: Selektivno lasersko sintranje
polimerov (ISO/ASTM 52911-2:2019)

Additive manufacturing - Design - Part 2: Laser-based powder bed fusion of polymers

(ISO/ASTM 52911-2:2019)

Additive Fertigung - Technische Konstruktionsrichtlinie für Pulverbettfusion - Teil 2:

Laserbasierte Pulverbettfusion von Polymeren (ISO/ASTM 52911-2:2019)

Fabrication additive - Conception - Partie 2: Fusion laser sur lit de poudre polymère

(ISO/ASTM 52911-2:2019)
Ta slovenski standard je istoveten z: EN ISO/ASTM 52911-2:2019
ICS:
25.030 3D-tiskanje Additive manufacturing
SIST EN ISO/ASTM 52911-2:2020 en,fr,de

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

---------------------- Page: 1 ----------------------
SIST EN ISO/ASTM 52911-2:2020
---------------------- Page: 2 ----------------------
SIST EN ISO/ASTM 52911-2:2020
EN ISO/ASTM 52911-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2019
EUROPÄISCHE NORM
ICS 25.030
English Version
Additive manufacturing - Design - Part 2: Laser-based
powder bed fusion of polymers (ISO/ASTM 52911-2:2019)

Fabrication additive - Conception - Partie 2: Fusion Additive Fertigung - Konstruktion - Teil 2:

laser sur lit de poudre polymère (ISO/ASTM 52911- Laserbasierte Pulverbettfusion von Polymeren

2:2019) (ISO/ASTM 52911-2:2019)
This European Standard was approved by CEN on 8 September 2019.

This European Standard was corrected and reissued by the CEN-CENELEC Management Centre on 6 November 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 NORMALISATIO N
EUROPÄISCHES KOMITEE FÜR NORMUN G
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 52911-2:2019 E

worldwide for CEN national Members.
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SIST EN ISO/ASTM 52911-2:2020
EN ISO/ASTM 52911-2:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO/ASTM 52911-2:2020
EN ISO/ASTM 52911-2:2019 (E)
European foreword

This document (EN ISO/ASTM 52911-2:2019) 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 April 2020, and conflicting national standards shall be

withdrawn at the latest by April 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 52911-2:2019 has been approved by CEN as EN ISO/ASTM 52911-2:2019

without any modification.
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SIST EN ISO/ASTM 52911-2:2020
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SIST EN ISO/ASTM 52911-2:2020
INTERNATIONAL ISO/ASTM
STANDARD 52911-2
First edition
2019-09
Additive manufacturing — Design —
Part 2:
Laser-based powder bed fusion of
polymers
Fabrication additive — Conception —
Partie 2: Fusion laser sur lit de poudre polymère
Reference number
ISO/ASTM 52911-2:2019(E)
ISO/ASTM International 2019
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SIST EN ISO/ASTM 52911-2:2020
ISO/ASTM 52911-2:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© 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: +41 22 749 01 11 Phone: +610 832 9634
Fax: +41 22 749 09 47 Fax: +610 832 9635
Email: copyright@iso.org Email: khooper@astm.org
Website: www.iso.org Website: www.astm.org
Published in Switzerland
ii © ISO/ASTM International 2019 – All rights reserved
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SIST EN ISO/ASTM 52911-2:2020
ISO/ASTM 52911-2:2019(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 ...................................................................................................................................................................................... 3

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) ................................................................................. 5

5.6.1 General...................................................................................................................................................................................... 5

5.6.2 Islands ....................................................................................................................................................................................... 5

5.6.3 Overhang ................................................................................................................................................................................. 6

5.6.4 Stair-step effect ................................................................................................................................................................. 6

5.7 Dimensional, form and positional accuracy ................................................................................................................... 6

5.8 Data quality, resolution, representation ........................................................................................................................... 6

6 Design guidelines for laser-based powder bed fusion of polymers (LB-PBF/P) ...............................7

6.1 General ........................................................................................................................................................................................................... 7

6.2 Material and structural characteristics .............................................................................................................................. 7

6.3 Anisotropy of the material characteristics...................................................................................................................... 8

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

6.4.1 General...................................................................................................................................................................................... 9

6.4.2 Powder coating .................................................................................................................................................................. 9

6.4.3 Part location in the build chamber ................................................................................................................... 9

6.4.4 Oversintering ...................................................................................................................................................................... 9

6.4.5 Packing parts efficiently in the build chamber ...................................................................................... 9

6.5 Surface roughness .............................................................................................................................................................................10

6.6 Post-production finishing ...........................................................................................................................................................10

6.7 Design considerations....................................................................................................................................................................11

6.7.1 Allowing for powder removal ............................................................................................................................11

6.7.2 Reducing warpage .......................................................................................................................................................11

6.7.3 Wall thickness .................................................................................................................................................................11

6.7.4 Gaps, cylinders and holes ......................................................................................................................................11

6.7.5 Lattice structures .........................................................................................................................................................12

6.7.6 Fluid channels .................................................................................................................................................................12

6.7.7 Springs and elastic elements ..............................................................................................................................13

6.7.8 Connecting elements and fasteners..............................................................................................................13

6.7.9 Static assemblies ...........................................................................................................................................................14

6.7.10 Movable assemblies ...................................................................................................................................................15

6.7.11 Bearings ................................................................................................................................................................................15

6.7.12 Joints ........................................................................................................................................................................................15

6.7.13 Integrated markings ..................................................................................................................................................16

6.7.14 Cutting and joining ......................................................................................................................................................16

6.8 Example applications .....................................................................................................................................................................17

6.8.1 Functional toy car with integrated spring ..............................................................................................17

6.8.2 Robot gripper ...................................................................................................................................................................18

7 General design consideration ..............................................................................................................................................................19

© ISO/ASTM International 2019 – All rights reserved iii
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SIST EN ISO/ASTM 52911-2:2020
ISO/ASTM 52911-2:2019(E)

Bibliography .............................................................................................................................................................................................................................20

iv © ISO/ASTM International 2019 – All rights reserved
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SIST EN ISO/ASTM 52911-2:2020
ISO/ASTM 52911-2:2019(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
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SIST EN ISO/ASTM 52911-2:2020
ISO/ASTM 52911-2:2019(E)
Introduction

Laser-based powder bed fusion of polymers (LB-PBF/P) describes an additive manufacturing (AM)

process and offers an additional manufacturing option alongside established processes. LB-PBF/P 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 LB-PBF/P 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 LB-PBF/P 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

intended that the series will include ISO 52911-1 on laser-based powder bed fusion of metals (LB-

PBF/M), this document on LB-PBF/P, and ISO 52911-3 on electron beam powder bed fusion of metals

(EB-PBF/M). Clauses 1 to 5, where general information including terminology and the PBF process is

provided, are similar throughout the series. The subsequent clauses focus on the specific technology.

[8]

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 LB-PBF/P.

It will help practitioners to explore the benefits of LB-PBF/P and to recognize the process-related

[4]

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.
vi © ISO/ASTM International 2019 – All rights reserved
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SIST EN ISO/ASTM 52911-2:2020
INTERNATIONAL STANDARD ISO/ASTM 52911-2:2019(E)
Additive manufacturing — Design —
Part 2:
Laser-based powder bed fusion of polymers
1 Scope

This document specifies the features of laser-based powder bed fusion of polymers (LB-PBF/P) 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 https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
downskin area
(sub-)area where the normal vector n projection on the z-axis is negative
Note 1 to entry: See Figure 1.
3.2
downskin angle
angle between the plane of the build platform and the downskin area (3.1)

Note 1 to entry: The angle lies between 0° (parallel to the build platform) and 90° (perpendicular to the build

platform).
Note 2 to entry: See Figure 1.
© ISO/ASTM International 2019 – All rights reserved 1
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SIST EN ISO/ASTM 52911-2:2020
ISO/ASTM 52911-2:2019(E)
3.3
upskin area
(sub-)area where the normal vector n projection on the z-axis is positive
Note 1 to entry: See Figure 1.
3.4
upskin angle
angle between the build platform plane and the upskin area (3.3)

Note 1 to entry: The angle lies between 0° (parallel to the build platform) and 90° (perpendicular to the build

platform).
Note 2 to entry: See Figure 1.
Key
z build direction
SOURCE VDI 3405-3:2015.

Figure 1 — Upskin and downskin areas U and D, upskin and downskin angles υ and δ, normal

vector n
4 Symbols and abbreviated terms
4.1 Symbols
The symbols given in Table 1 are used in this document.
Table 1 — Symbols
Symbol Designation Unit
a overhang mm
D downskin area mm
I island mm
normal vector —
P part mm
2 © ISO/ASTM International 2019 – All rights reserved
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SIST EN ISO/ASTM 52911-2:2020
ISO/ASTM 52911-2:2019(E)
Table 1 (continued)
Symbol Designation Unit
Ra mean roughness µm
Rz average surface roughness µm
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
CAD computer aided design
EB-PBF/M electron beam powder bed fusion of metals
LB-PBF laser-based powder bed fusion

LB-PBF/M laser-based powder bed fusion of metals (also known as e.g. laser beam melting, selective

laser melting)

LB-PBF/P laser-based powder bed fusion of polymers (also known as e.g. laser beam melting,

selective laser melting)
MRI magnetic resonance imaging
PBF powder bed fusion
STL stereolithography format or surface tessellation language
3MF 3D manufacturing format
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.

5.2 Size of the parts

The size of the parts is limited by the working area/working volume of the PBF-machine. Also, the

occurrence of cracks and deformation due to residual stresses limits the maximum part size. Another

important practical factor that limits 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. Also, the cost

of powder needed to fill the bed to the required volume (part depth × bed area) may be a consideration.

© ISO/ASTM International 2019 – All rights reserved 3
---------------------- Page: 15 ----------------------
SIST EN ISO/ASTM 52911-2:2020
ISO/ASTM 52911-2:2019(E)

Powder reuse rules impact this cost significantly. If no reuse is allowed, then all powder is scrapped

regardless of solidified volume.
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:

— Parts can be manufactured to near-net shape (i.e. close to the finished shape and size), without

further post processing tools, in a single process step.

— 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:
[17]
— free-form geometries, e.g. organic structures ,
— topologically optimized structures,
— infill structures, e.g. honeycomb, sandwich and mesh structures.
— The degree of part complexity is largely unrelated to production costs.

— Assembly and joining processes can be reduced through single-body construction.

— Overall part characteristics can be selectively configured by adjusting process parameters locally.

— Reduction in lead times until part production.
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 injection

moulding and casting. Material properties can be influenced significantly by process settings and

control.
4 © ISO/ASTM International 2019 – All rights reserved
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SIST EN ISO/ASTM 52911-2:2020
ISO/ASTM 52911-2:2019(E)
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 build costs.

Parts shall be oriented in such a way that the build height is kept to a minimum, provided that the

geometry permits such an orientation.

— If the intention is to manufacture a larger number of units, then the build space shall be used as

efficiently as possible. Provided that the part geometry permits such orientation, strategies for

reorientation and nesting shall be utilized to maximize the available build space.

— The powder that remains in the system after a build can be reused in some cases. Reuse depends

on the application, material, and specific requirements. Powder changes can be inefficient and

time consuming. Although they are necessary when changing material type, powd
...

SLOVENSKI STANDARD
SIST EN ISO/ASTM 52911-2:2020
01-januar-2020

Aditivna proizvodnja - Načrtovanje - 2. del: Laserska fuzija polimernih prahastih

plasti (ISO/ASTM 52911-2:2019)

Additive manufacturing - Design - Part 2: Laser-based powder bed fusion of polymers

(ISO/ASTM 52911-2:2019)

Additive Fertigung - Technische Konstruktionsrichtlinie für Pulverbettfusion - Teil 2:

Laserbasierte Pulverbettfusion von Polymeren (ISO/ASTM 52911-2:2019)

Fabrication additive - Conception - Partie 2: Fusion laser sur lit de poudre polymère

(ISO/ASTM 52911-2:2019)
Ta slovenski standard je istoveten z: EN ISO/ASTM 52911-2:2019
ICS:
25.030 3D-tiskanje Additive manufacturing
SIST EN ISO/ASTM 52911-2:2020 en,fr,de

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

---------------------- Page: 1 ----------------------
SIST EN ISO/ASTM 52911-2:2020
---------------------- Page: 2 ----------------------
SIST EN ISO/ASTM 52911-2:2020
EN ISO/ASTM 52911-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2019
EUROPÄISCHE NORM
ICS 25.030
English Version
Additive manufacturing - Design - Part 2: Laser-based
powder bed fusion of polymers (ISO/ASTM 52911-2:2019)

Fabrication additive - Conception - Partie 2: Fusion Additive Fertigung - Konstruktion - Teil 2:

laser sur lit de poudre polymère (ISO/ASTM 52911- Laserbasierte Pulverbettfusion von Polymeren

2:2019) (ISO/ASTM 52911-2:2019)
This European Standard was approved by CEN on 8 September 2019.

This European Standard was corrected and reissued by the CEN-CENELEC Management Centre on 6 November 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 NORMALISATIO N
EUROPÄISCHES KOMITEE FÜR NORMUN G
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 52911-2:2019 E

worldwide for CEN national Members.
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EN ISO/ASTM 52911-2:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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EN ISO/ASTM 52911-2:2019 (E)
European foreword

This document (EN ISO/ASTM 52911-2:2019) 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 April 2020, and conflicting national standards shall be

withdrawn at the latest by April 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 52911-2:2019 has been approved by CEN as EN ISO/ASTM 52911-2:2019

without any modification.
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SIST EN ISO/ASTM 52911-2:2020
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SIST EN ISO/ASTM 52911-2:2020
INTERNATIONAL ISO/ASTM
STANDARD 52911-2
First edition
2019-09
Additive manufacturing — Design —
Part 2:
Laser-based powder bed fusion of
polymers
Fabrication additive — Conception —
Partie 2: Fusion laser sur lit de poudre polymère
Reference number
ISO/ASTM 52911-2:2019(E)
ISO/ASTM International 2019
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ISO/ASTM 52911-2:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© 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
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Published in Switzerland
ii © ISO/ASTM International 2019 – All rights reserved
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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 ...................................................................................................................................................................................... 3

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) ................................................................................. 5

5.6.1 General...................................................................................................................................................................................... 5

5.6.2 Islands ....................................................................................................................................................................................... 5

5.6.3 Overhang ................................................................................................................................................................................. 6

5.6.4 Stair-step effect ................................................................................................................................................................. 6

5.7 Dimensional, form and positional accuracy ................................................................................................................... 6

5.8 Data quality, resolution, representation ........................................................................................................................... 6

6 Design guidelines for laser-based powder bed fusion of polymers (LB-PBF/P) ...............................7

6.1 General ........................................................................................................................................................................................................... 7

6.2 Material and structural characteristics .............................................................................................................................. 7

6.3 Anisotropy of the material characteristics...................................................................................................................... 8

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

6.4.1 General...................................................................................................................................................................................... 9

6.4.2 Powder coating .................................................................................................................................................................. 9

6.4.3 Part location in the build chamber ................................................................................................................... 9

6.4.4 Oversintering ...................................................................................................................................................................... 9

6.4.5 Packing parts efficiently in the build chamber ...................................................................................... 9

6.5 Surface roughness .............................................................................................................................................................................10

6.6 Post-production finishing ...........................................................................................................................................................10

6.7 Design considerations....................................................................................................................................................................11

6.7.1 Allowing for powder removal ............................................................................................................................11

6.7.2 Reducing warpage .......................................................................................................................................................11

6.7.3 Wall thickness .................................................................................................................................................................11

6.7.4 Gaps, cylinders and holes ......................................................................................................................................11

6.7.5 Lattice structures .........................................................................................................................................................12

6.7.6 Fluid channels .................................................................................................................................................................12

6.7.7 Springs and elastic elements ..............................................................................................................................13

6.7.8 Connecting elements and fasteners..............................................................................................................13

6.7.9 Static assemblies ...........................................................................................................................................................14

6.7.10 Movable assemblies ...................................................................................................................................................15

6.7.11 Bearings ................................................................................................................................................................................15

6.7.12 Joints ........................................................................................................................................................................................15

6.7.13 Integrated markings ..................................................................................................................................................16

6.7.14 Cutting and joining ......................................................................................................................................................16

6.8 Example applications .....................................................................................................................................................................17

6.8.1 Functional toy car with integrated spring ..............................................................................................17

6.8.2 Robot gripper ...................................................................................................................................................................18

7 General design consideration ..............................................................................................................................................................19

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Bibliography .............................................................................................................................................................................................................................20

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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 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.
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Introduction

Laser-based powder bed fusion of polymers (LB-PBF/P) describes an additive manufacturing (AM)

process and offers an additional manufacturing option alongside established processes. LB-PBF/P 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 LB-PBF/P 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 LB-PBF/P 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

intended that the series will include ISO 52911-1 on laser-based powder bed fusion of metals (LB-

PBF/M), this document on LB-PBF/P, and ISO 52911-3 on electron beam powder bed fusion of metals

(EB-PBF/M). Clauses 1 to 5, where general information including terminology and the PBF process is

provided, are similar throughout the series. The subsequent clauses focus on the specific technology.

[8]

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 LB-PBF/P.

It will help practitioners to explore the benefits of LB-PBF/P and to recognize the process-related

[4]

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.
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INTERNATIONAL STANDARD ISO/ASTM 52911-2:2019(E)
Additive manufacturing — Design —
Part 2:
Laser-based powder bed fusion of polymers
1 Scope

This document specifies the features of laser-based powder bed fusion of polymers (LB-PBF/P) 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 https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
downskin area
(sub-)area where the normal vector n projection on the z-axis is negative
Note 1 to entry: See Figure 1.
3.2
downskin angle
angle between the plane of the build platform and the downskin area (3.1)

Note 1 to entry: The angle lies between 0° (parallel to the build platform) and 90° (perpendicular to the build

platform).
Note 2 to entry: See Figure 1.
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3.3
upskin area
(sub-)area where the normal vector n projection on the z-axis is positive
Note 1 to entry: See Figure 1.
3.4
upskin angle
angle between the build platform plane and the upskin area (3.3)

Note 1 to entry: The angle lies between 0° (parallel to the build platform) and 90° (perpendicular to the build

platform).
Note 2 to entry: See Figure 1.
Key
z build direction
SOURCE VDI 3405-3:2015.

Figure 1 — Upskin and downskin areas U and D, upskin and downskin angles υ and δ, normal

vector n
4 Symbols and abbreviated terms
4.1 Symbols
The symbols given in Table 1 are used in this document.
Table 1 — Symbols
Symbol Designation Unit
a overhang mm
D downskin area mm
I island mm
normal vector —
P part mm
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Table 1 (continued)
Symbol Designation Unit
Ra mean roughness µm
Rz average surface roughness µm
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
CAD computer aided design
EB-PBF/M electron beam powder bed fusion of metals
LB-PBF laser-based powder bed fusion

LB-PBF/M laser-based powder bed fusion of metals (also known as e.g. laser beam melting, selective

laser melting)

LB-PBF/P laser-based powder bed fusion of polymers (also known as e.g. laser beam melting,

selective laser melting)
MRI magnetic resonance imaging
PBF powder bed fusion
STL stereolithography format or surface tessellation language
3MF 3D manufacturing format
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.

5.2 Size of the parts

The size of the parts is limited by the working area/working volume of the PBF-machine. Also, the

occurrence of cracks and deformation due to residual stresses limits the maximum part size. Another

important practical factor that limits 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. Also, the cost

of powder needed to fill the bed to the required volume (part depth × bed area) may be a consideration.

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Powder reuse rules impact this cost significantly. If no reuse is allowed, then all powder is scrapped

regardless of solidified volume.
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:

— Parts can be manufactured to near-net shape (i.e. close to the finished shape and size), without

further post processing tools, in a single process step.

— 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:
[17]
— free-form geometries, e.g. organic structures ,
— topologically optimized structures,
— infill structures, e.g. honeycomb, sandwich and mesh structures.
— The degree of part complexity is largely unrelated to production costs.

— Assembly and joining processes can be reduced through single-body construction.

— Overall part characteristics can be selectively configured by adjusting process parameters locally.

— Reduction in lead times until part production.
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 injection

moulding and casting. Material properties can be influenced significantly by process settings and

control.
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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 build costs.

Parts shall be oriented in such a way that the build height is kept to a minimum, provided that the

geometry permits such an orientation.

— If the intention is to manufacture a larger number of units, then the build space shall be used as

efficiently as possible. Provided that the part geometry permits such orientation, strategies for

reorientation and nesting shall be utilized to maximize the available build space.

— The powder that remains in the system after a build can be reused in some cases. Reuse depends

on the application, material, and specific requirements. Powder changes can be inefficient and

time consuming. Although they are necessary when changing material type, po
...

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