SIST-TP CEN ISO/ASTM/TR 52906:2022
(Main)Additive manufacturing - Non-destructive testing - Intentionally seeding flaws in metallic parts (ISO/ASTM TR 52906:2022)
Additive manufacturing - Non-destructive testing - Intentionally seeding flaws in metallic parts (ISO/ASTM TR 52906:2022)
This document is intended to serve as a best practice for the identification and “seeding” of
nondestructively detectable flaw replicas of metal alloy PBF-LB and DED processes. Three
seeding categories are described: 1. process flaws through CAD design, 2. build parameter
manipulation, 3. subtractive manufacturing, and 4. depositing/inserting flaws after processing.
These include flaws present within as-deposited materials, post heat-treated or HIP processed
material, and those flaws made detectable because of post-processing operations. Geometrical
aspects or measurement are not the subjects of this document.
Additive Fertigung - Zerstörungsfreie Prüfung und Bewertung - Bewusstes Einbringen von Fehlern in Bauteilen (ISO/ASTM TR 52906:2022)
Dieses Dokument dient als Leitfaden für die Identifizierung und das „Einbringen“ von zerstörungsfrei nachweisbaren Nachbildungen von Fehlern bei PBF- und DED-Verfahren für Metalllegierungen. Es werden drei Kategorien zum Einbringen von Fehlern beschrieben:
a) Prozessmängel durch CAD-Design;
b) Manipulation der Bauparameter;
c) subtraktive Fertigung.
Dazu gehören Fehler, die in den Werkstoffen nach der Ablagerung, nach der Wärmebehandlung oder nach der HIP-Bearbeitung zu finden sind, sowie Fehler, die aufgrund von Nachbearbeitungsvorgängen festgestellt werden. Geometrische Aspekte oder Messungen sind nicht Gegenstand dieses Dokuments.
WARNUNG — Dieses Dokument erhebt nicht den Anspruch, alle Sicherheitsprobleme zu behandeln, die im Zusammenhang mit ihrer Anwendung, wenn überhaupt, auftreten. Es liegt in der Verantwortung des Anwenders dieses Dokuments, entsprechende Maßnahmen zum Arbeits- und Gesundheitsschutz zu ergreifen sowie vor der Verwendung die Anwendbarkeit von gesetzlichen Einschränkungen festzustellen.
Fabrication additive - Essais non destructifs - Implantation intentionnelle de défauts dans les pièces métalliques (ISO/ASTM TR 52906:2022)
Le présent document est destiné à servir de bonne pratique pour l'identification et «l'implantation» de répliques de défauts détectables de manière non destructive par les procédés PBF et DED en alliage métallique. Trois catégories d'implantation sont décrites:
a) les défauts du procédé par la conception CAO;
b) la manipulation des paramètres de fabrication;
c) la fabrication soustractive.
Cela comprend les défauts présents dans les matériaux tels que déposés, dans les matériaux traités par post-traitement thermique ou par HIP, et des défauts rendus détectables par les opérations de post-traitement. Les aspects géométriques ou les mesures ne font pas l'objet du présent document.
ATTENTION — Le présent document n'a pas pour but de traiter tous les problèmes de sécurité, le cas échéant, liés à son application. Il est de la responsabilité de l'utilisateur du présent document d'établir des pratiques de sécurité et d'hygiène appropriées, et de déterminer l'applicabilité des restrictions réglementaires avant utilisation.
Aditivna proizvodnja - Neporušitveno preskušanje - Namerno vnešene nepravilnosti v kovinskih delcih (ISO/ASTM TR 52906:2022)
Ta dokument je namenjen za uporabo kot primer najboljše prakse za ugotavljanje in »vnašanje« poustvarjenih nepravilnosti v procese laserskega pretaljevanja kovinskega prahu (PBF-LB) in laserskega navarjanja (DED) kovinskih zlitin, ki jih je mogoče zaznati z neporušitveno metodo. Opisane so tri kategorije vnašanja: 1. procesne nepravilnosti prek oblikovanja CAD; 2. manipuliranje s parametrom izdelave; 3. proizvodnja z odvzemom in 4) odlaganje/vstavljanje nepravilnosti po obdelavi. Slednje vključujejo nepravilnosti, prisotne v navarjenih materialih brez naknadne obdelave, v materialih z naknadno toplotno obdelavo ali obdelavo HIP, in nepravilnosti, zaznane zaradi postopkov naknadne obdelave. Ta dokument ne zajema geometrijskih vidikov merjenja.
General Information
Buy Standard
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TP CEN ISO/ASTM/TR 52906:2022
01-september-2022
Aditivna proizvodnja - Neporušitveno preskušanje - Namerno vnešene
nepravilnosti v kovinskih delcih (ISO/ASTM TR 52906:2022)
Additive manufacturing - Non-destructive testing - Intentionally seeding flaws in metallic
parts (ISO/ASTM TR 52906:2022)
Additive Fertigung - Zerstörungsfreie Prüfung und Bewertung - Bewusstes Einbringen
von Fehlern in Bauteilen (ISO/ASTM TR 52906:2022)
Fabrication additive - Essais non destructifs - Implantation intentionnelle de défauts dans
les pièces métalliques (ISO/ASTM TR 52906:2022)
Ta slovenski standard je istoveten z: CEN ISO/ASTM/TR 52906:2022
ICS:
19.100 Neporušitveno preskušanje Non-destructive testing
25.030 3D-tiskanje Additive manufacturing
SIST-TP CEN ISO/ASTM/TR 52906:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
---------------------- Page: 2 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
CEN ISO/ASTM/TR
TECHNICAL REPORT
52906
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
May 2022
ICS
English Version
Additive manufacturing - Non-destructive testing -
Intentionally seeding flaws in metallic parts
(ISO/ASTM/TR 52906:2022)
Fabrication additive - Essais non destructifs - Additive Fertigung - Zerstörungsfreie Prüfung und
Implantation intentionnelle de défauts dans les pièces Bewertung - Bewusstes Einbringen von Fehlern in
métalliques (ISO/ASTM/TR 52906:2022) Bauteilen (ISO/ASTM/TR 52906:2022)
This Technical Report was approved by CEN on 28 April 2022. It has been drawn up by the Technical Committee CEN/TC 438.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/ASTM/TR 52906:2022 E
worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
CEN ISO/ASTM/TR 52906:2022 (E)
Contents Page
European foreword . 3
2
---------------------- Page: 4 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
CEN ISO/ASTM/TR 52906:2022 (E)
European foreword
This document (CEN ISO/ASTM/TR 52906:2022) 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.
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.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
Endorsement notice
The text of ISO/ASTM TR 52906:2022 has been approved by CEN as CEN ISO/ASTM/TR 52906:2022
without any modification.
3
---------------------- Page: 5 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
---------------------- Page: 6 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
TECHNICAL ISO/ASTM TR
REPORT 52906
First edition
2022-05
Additive manufacturing — Non-
destructive testing — Intentionally
seeding flaws in metallic parts
Fabrication additive — Essais non destructifs — Implantation
intentionnelle de défauts dans les pièces métalliques
Reference number
ISO/ASTM TR 52906:2022(E)
© ISO/ASTM International 2022
---------------------- Page: 7 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/ASTM International 2022
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: +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 2022 – All rights reserved
---------------------- Page: 8 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Typical AM flaws . 3
6 Procedure to produce replicas . 7
7 Seeding approaches .7
7.1 General . 7
7.2 CAD seeding . 8
7.3 AM process manipulation replicas . 10
7.3.1 General . 10
7.3.2 Entrapped unsintered powder. 11
7.3.3 Manual insertion of high-density inclusions . 11
7.4 Post-production mechanical introduction of replicas . 11
7.5 Significance and use for homogeneity .12
8 AM process manipulation for L-PBF and L-DED .14
8.1 General . 14
8.2 AM machine parameter manipulation . 14
8.3 Applicable flaw-seeding approaches as a function of desired flaw type .15
8.3.1 General .15
8.3.2 Porosity or voids (increased power density) . 15
8.3.3 Surface-connected flaws . 15
8.4 Applicable flaw-seeding approach as a function of AM process . 16
8.5 Applicable flaw-seeding approach as a function of AM material . 17
8.5.1 General . 17
8.5.2 High-density inclusions . 18
9 Applicable flaw-seeding approach as a function of post processing machining .18
9.1 General . 18
9.2 Mechanical machining . 18
9.3 Electrode discharge machining replicas . 18
9.4 Laser drilling replicas . 18
Bibliography .20
iii
© ISO/ASTM International 2022 – All rights reserved
---------------------- Page: 9 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2022(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 can 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 on 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 the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by 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, and in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 438, Additive manufacturing, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
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.
iv
© ISO/ASTM International 2022 – All rights reserved
---------------------- Page: 10 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2022(E)
Introduction
This document provides information for intentionally seeding flaws in additively manufactured parts
1)
and complements ISO/ASTM TR 52905 .
The different AM building descriptions can be found readily in published standards (see ISO 17296-2)
and scientific papers.
Jargon commonly used in the literature describing AM metal process defects includes “balling”,
“fireworks”, “smoke” and often are not specific to the morphology of the defect and often result from
widely differing mechanisms of formation.
When defining terms specific to AM metal flaws it may be useful to review some examples related to
welding technology.
This document is for the creation of seeded replicas supports the user’s understanding not only for the
characterization of actual flaws with respect to physical morphology but also for the materials and
mechanisms of formation, location, and orientation. In addition, the fundamentals of the processes
creating the replica (e.g. PBF or DED with regard to the heat sources electron beam (EB), laser beam
(LB) or AP (arc processes) also need to be considered). The intentional seeding to produce flaw replicas
can match the character of the actual flaw as closely as possible.
The reference photomicrographs or non-destructive testing images included in this document are in no
way to be construed as specifications. These reference photomicrographs and non-destructive testing
images are offered primarily to permit examples of “flaws” or replicate images thereof. They can be
used for comparison of reports. Flaw seeding will be discussed without context to a specific part,
location, or dimension. The material alloy will be provided as known. With some flaws the material
alloy may not be as important, for example, a pore may reside in any number of alloys. It can be noted
that there is currently no proven method for controlled and replicable seeding of intimate disbonds
(sometimes known as “kissing bonds”) – where two surfaces are in intimate or close contact, but with
compromised adhesion – in AM parts so this feature is, therefore, currently out of scope.
This document will not go into the fundamentals of each process but rather identify the parameters
within each process that can lead to the intentional seeding of AM structures.
1) In preparation. Stage at the time of publication ISO/ASTM DTR 52905:2022.
v
© ISO/ASTM International 2022 – All rights reserved
---------------------- Page: 11 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
---------------------- Page: 12 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
TECHNICAL REPORT ISO/ASTM TR 52906:2022(E)
Additive manufacturing — Non-destructive testing —
Intentionally seeding flaws in metallic parts
1 Scope
This document is intended to serve as a best practice for the identification and “seeding” of
nondestructively detectable flaw replicas of metal alloy PBF and DED processes. Three seeding
categories are described:
a) process flaws through CAD design;
b) build parameter manipulation;
c) subtractive manufacturing.
These include flaws present within as-deposited materials, post heat-treated or HIP processed
material, and those flaws made detectable because of post-processing operations. Geometrical aspects
or measurement are not the subjects of this document.
WARNING — This document does not purport to address all of the safety concerns, if any,
associated with its use. It is the responsibility of the user of this document to establish
appropriate safety and health practices and determine the applicability of regulatory limitations
prior to use.
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, Standard Terminology for Additive Manufacturing — General Principles —Terminology
ASTM B243, Standard Terminology of Powder Metallurgy
ASTM E7, Standard Terminology Relating to Metallography
ASTM E1316, Standard Terminology for Nondestructive Examinations
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/ASTM 52900, ASTM E7,
ASTM B243, ASTM E1316 and the following apply.
NOTE Terms for AM metal technology flaws are logically divided between PBF and DED categories of
processes.
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
coupon
piece of material from which a specimen is prepared
1
© ISO/ASTM International 2022 – All rights reserved
---------------------- Page: 13 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2022(E)
3.2
flaw classification
classification approach that provides a high-level system based on a primary characteristic or a
combination of characteristics
Note 1 to entry: Flaw classification may include similar flaw types that were created differently.
3.3
inclusion
foreign material held mechanically
Note 1 to entry: Inclusions are typically oxides, nitrides, hydrides, carbides, or combinations thereof being
formed due to contamination of the chamber gas, or already be present in the metal powder.
3.4
keyhole
type of porosity characterised by a circular depression formed due to instability of the vapour cavity
during processing
3.5
pore
inherent or induced cavity within a powder particle or within an object not connected to an exterior
surface
3.6
porosity
presence of small voids in a part making it less than fully dense
3.7
replica
intentional manipulated condition (flaw) to serve as the “seed” in a coupon (3.1) representing a known
flaw type
3.8
seeding
act of intentionally creating flaws, through CAD or manipulation of designated processing parameters,
that results in the placement of the anticipated replica (3.7) or the act of intentionally creating a replica
(3.7) through the insertion of a foreign object
3.9
sintering
process of heating a powder metal compact to increase density and/or improve mechanical properties
via solid state diffusion
3.10
surface-connected flaw
flaw that is in the body of the material but its boundaries reach to the material’s surface
3.11
unsintered
powder unaffected or affected but not fully consolidated during the additive manufacturing printing
process
4 Abbreviated terms
AM Additive Manufacturing
BM Base Metal
2
© ISO/ASTM International 2022 – All rights reserved
---------------------- Page: 14 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2022(E)
CAD Computer-Aided Design/Computer-Aided Drafting/Computer-Aided Drawing
CNC Computer Numerical Control
DDC Ductility-Dip Cracking
DED Directed Energy Deposition
EB-DED Electron Beam Directed Energy Deposition
DR Digital Radiography (non-film)
EB-PBF Electron Beam Powder Bed Fusion
EDM Electrode Discharge Machining
GMA-DED Gas Metal Arc Directed Energy Deposition
HAZ Heat Affected Zone
HIP Hot Isostatic Pressing
LC Liquation Crack
L-DED Laser Directed Energy Deposition
L-PBF Laser Beam Powder Bed Fusion
MB Metal Base
NDE Non-destructive evaluation
NDT Non-destructive Testing
OEM Original Equipment Manufacturer
PBF Powder Bed Fusion
PSD Particle Size Distribution
RT Radiography Testing(film)
RQI Representative Quality Indicator
SC Solidification Crack
T Temperature melting point
m
WM Weld Metal
XCT X-ray Computed Tomography
5 Typical AM flaws
Typically, additive manufacturing flaws in materials fabricated using optimised parameters have small
spherical flaws. Builds with less developed parameters may have a keyhole or larger angular pores.
However, high value components are often screened for flaws at a level determined by fracture analysis
such as those described below. The ability to create replicas to support the NDT detection capability
of complex structures is unique to additive manufacturing and can be considered when standard
inspection techniques are not adequate to ensure inspection reliability.
3
© ISO/ASTM International 2022 – All rights reserved
---------------------- Page: 15 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2022(E)
The occurrence of unintentional flaws during the additive manufacturing build is a possibility. The flaw
classification has been laid out in ISO/ASTM TR 52905 both L-PBF and DED. These flaws are: layer-
defects (horizontal lack of fusion), cross-layer (vertical lack of fusion), unconsolidated powder, trapped
powder, inclusion, layer shift, porosity and void; moreover, incomplete fusion, hole and cracking. It is
important to highlight that some DED defects are similar to those produced during the welding process,
while for L-PBF some defects are unique.
In addition to flaws created to replicate naturally occurring anomalies, replicas may be generated
to serve as targets that can be used to understand x-ray, ultrasonic or other NDT capabilities (see
Figure 1). It is important that the fabricator of such replicas understands the physics of the NDT’s
method for which the flaws will be used. Capabilities demonstrations include detection in a specific
[5]
complex geometry such as a Representative Quality Indicator (RQI) according to ASTM E1817 , or
detection at a specific orientation relating to the radiation beam. This replica is “seeded” intentionally
around the needs of the demonstrations. Ultrasonic sensing may find applicability through the technical
[3]
approach of ASTM E127 . Additionally, some of these seeding methods are implemented and detection
capabilities of seven NDT methods are assessed in ISO/ASTM TR 52905.
It has been found that replica size, orientation, and location can be designed into the build model to
create shapes (spheres, cubes, and rectangular prisms), sizes (lengths and diameters), and depths. An
example is shown in Figure 1 where embedded defects were designed into the step wedge with CAD
software, and since they are embedded with no powder removal vent, they are filled with unmelted
powder (unconsolidated powder/trapped powder).
a) CAD model showing the set of clusters and dimensions of the holes in the airfoil
4
© ISO/ASTM International 2022 – All rights reserved
---------------------- Page: 16 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2022(E)
b) XCT scan displaying the visibility of the replicas seeded at different locations
and those that are not visible
Key
1 sets of holes containing 3 cluster
2 number of holes per cluster
3 holes dimensions per cluster
a
All 4 are visible.
b
⌀ 0,1 mm not visible.
Figure 1 — Example of RQI generic airfoil built on Ti-6Al-4V
With adjustments to the optimum build parameters, replicas can provide a desired off-nominal build
parameter. The shape of the replica can be planar, elliptical, rounded or another modelled configuration.
Two such off-nominal build parameters for seeding replicas are lowering laser power and increasing
the trace width to that which is greater than optimal.
Both of these types of replicas can be used to show the various NDT methods detection potentials. For
example, the computed tomography scans of the seeding replicas resulted in different yet detectable
material density changes created by each build parameter adjustment. The level of detail and different
views possible through computed tomography is shown in Figure 2 and Figure 3. The images in
both figures are not comparatives as those only illustrate differences in the detail when different
magnifications and methods are used.
5
© ISO/ASTM International 2022 – All rights reserved
---------------------- Page: 17 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2022(E)
a) Computed tomography (XCT) slice image b) Microscopy image at 50×: large hatch spac-
ing
Figure 2 — Example of the difference in image when different magnification
a) Computed tomography (XCT) slice image b) Microscopy image at 50×
Figure 3 — Example of the difference in image when different method
Replicas that are open to the surface are producible through the predetermined width dimension in the
model. Figure 4 shows a model used to determine the width capability of the L-PBF machine. These are
linear-type replicas which can have the powder removed. Figure 5 shows the surface in the as-built and
polished conditions.
6
© ISO/ASTM International 2022 – All rights reserved
---------------------- Page: 18 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2022(E)
Figure 4 — Open to the surface replica at different width dimensions
Figure 5 — As-built (left) and polished (right) coupon of the model in Figure 4
6 Procedure to produce replicas
The introduction of the AM process replicas can be accomplished through the changing of machine
parameters, feedstock conditions or mechanical procedures. The most representative methods are:
— seeding methods;
— AM process manipulation;
— mechanical procedures.
7 Seeding approaches
7.1 General
The following subsections provide seeding approaches for flaw replication using CAD insertion,
manipulation of off-nominal processing and mechanical machining.
7
© ISO/ASTM International 2022 – All rights reserved
---------------------- Page: 19 ----------------------
SIST-TP CEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2022(E)
7.2 CAD seeding
This is the simplest, most direct, and most accurate method to seed defects on AM parts. Defects of
specific geometries (cylinders, spheres, etc.) are added in the CAD design at specific locations. Some
defects are open to the surface allowing the powder to be released and some are closed geometries
which will have trapped powder. This method is used in ISO/ASTM TR 52905 where artefacts were
built with such seeded defects and then tested with several NDT methods.
The typical AM only flaws were intentionally seeded in the following manner: horizontal cylinders
open to the surface for layer-defects (horizontal lack of fusion), vertical cylinders open to the surface
for cross-layer defects (vertical lack of fusion), spheres and cylinders not connected to the surface for
unconsolidated powder or trapped powder. Inclusions are represented by inserting foreign material
into the surface open seeded defects. Table 1 shows more detail of how this is achieved, while Figure 6
and Figure 7 show examples of a design S1 and the corresponding build in Inconel.
Table 1 — General AM Seeding by CAD design
Defect Classification CAD seed into geometry
Layer defects (horizontal Add horizontally oriented geometrical features to the part geometry at desired locations
lack of fusion) in the part. Geometries can include but not limited to: cylinders, cuboids, etc. Ideally open
to the surface to allow the powder to be released.
Cross Layer (vertical lack Add vertically oriented geometrical features to the part geometry at desired locations in
of fusion) the part.
...
SLOVENSKI STANDARD
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
01-februar-2022
[Not translated]
Additive manufacturing - Non-destructive testing - Intentionally seeding flaws in metallic
parts (ISO/ASTM PRF TR 52906:2021)
Additive Fertigung - Zerstörungsfreie Prüfung und Bewertung - Bewusstes Einbringen
von Fehlern in Bauteilen (ISO/ASTM PRF TR 52906:2021)
Fabrication additive - Essais non destructifs - Implantation intentionnelle de défauts dans
les pièces métalliques ISO/ASTM PRF TR 52906:2021)
Ta slovenski standard je istoveten z: FprCEN ISO/ASTM/TR 52906
ICS:
19.100 Neporušitveno preskušanje Non-destructive testing
25.030 3D-tiskanje Additive manufacturing
kSIST-TP FprCEN ISO/ASTM/TR en,fr,de
52906:2022
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
---------------------- Page: 2 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
TECHNICAL ISO/ASTM TR
REPORT 52906
First edition
Additive manufacturing — Non-
destructive testing — Intentionally
seeding flaws in metallic parts
Fabrication additive — Essais non destructifs — Implantation
intentionnelle de défauts dans les pièces métalliques
PROOF/ÉPREUVE
Reference number
ISO/ASTM TR 52906:2021(E)
© ISO/ASTM TR 2021
---------------------- Page: 3 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2021(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
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: +610 832 9635
Email: copyright@iso.org Email: khooper@astm.org
Website: www.iso.org Website: www.astm.org
Published in Switzerland
ii
PROOF/ÉPREUVE © ISO/ASTM International 2021 – All rights reserved
---------------------- Page: 4 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Typical AM flaws . 3
6 Procedure to produce replicas . 7
7 Seeding approaches .7
7.1 General . 7
7.2 CAD seeding . 7
7.3 AM process manipulation replicas . 9
7.3.1 General . 9
7.3.2 Entrapped unsintered powder. 10
7.3.3 Manual insertion of high-density inclusions . 10
7.4 Post-production mechanical introduction of replicas . 10
7.5 Significance and use for homogeneity . 11
8 AM process manipulation for L-PBF and L-DED .13
8.1 General .13
8.2 AM machine parameter manipulation . 13
8.3 Applicable flaw-seeding approaches as a function of desired flaw type . 14
8.3.1 General . 14
8.3.2 Porosity or voids (increased power density) . 14
8.3.3 Surface-connected flaws . 14
8.4 Applicable flaw-seeding approach as a function of AM process . 15
8.5 Applicable flaw-seeding approach as a function of AM material . 17
8.5.1 General . 17
8.5.2 High-density inclusions . 17
9 Applicable flaw-seeding approach as a function of post processing machining .17
9.1 General . 17
9.2 Mechanical machining . 17
9.3 Electrode discharge machining replicas . 17
9.4 Laser drilling replicas . 17
Bibliography .19
iii
© ISO/ASTM International 2021 – All rights reservedPR OOF/ÉPREUVE
---------------------- Page: 5 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2021(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 can 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 on 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 the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by 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, and in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 438, Additive manufacturing, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
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
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.
iv
PROOF/ÉPREUVE © ISO/ASTM International 2021 – All rights reserved
---------------------- Page: 6 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2021(E)
Introduction
This document provides information for intentionally seeding flaws in additively manufactured parts
1)
and complements ISO/ASTM TR 52905 .
The different AM building descriptions can be found readily in published standards (see ISO 17296-2)
and scientific papers.
Jargon commonly used in the literature describing AM metal process defect include “balling”,
“fireworks”, “smoke” and often are not specific to the morphology of the defect and often result from
widely differing mechanisms of formation.
When defining terms specific to AM metal flaws it may be useful to review some examples related to
welding technology.
This document is for the creation of seeded replicas supports the user’s understanding not only for the
characterization of actual flaws with respect to physical morphology but also for the materials and
mechanisms of formation, location, and orientation. In addition, the fundamentals of the processes
creating the replica (e.g. PBF or DED with regard to the heat sources electron beam (EB), laser beam
(LB) or AP (arc processes) also need to be considered). The intentional seeding to produce flaw replicas
can match the character of the actual flaw as closely as possible.
The reference photomicrographs or non-destructive testing images included in this document are in no
way to be construed as specifications. These reference photomicrographs and non-destructive testing
images are offered primarily to permit examples of “flaws” or replicate images thereof. They can be
used for comparison of reports. Flaw seeding will be discussed without context to a specific part,
location, or dimension. The material alloy will be provided as known. With some flaws the material
alloy may not be as important, for example, a pore may reside in any number of alloys. It can be noted
that there is currently no proven method for controlled and replicable seeding of intimate disbonds
(sometimes known as “kissing bonds”) – where two surfaces are in intimate or close contact, but with
compromised adhesion – in AM parts so this feature is, therefore, currently out of scope.
This document will not go into the fundamentals of each process but rather identify the parameters
within each process that can lead to the intentional seeding of AM structures.
1) In preparation. Stage at the time of publication ISO/ASTM DTR 52905:2021.
v
© ISO/ASTM International 2021 – All rights reservedPR OOF/ÉPREUVE
---------------------- Page: 7 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
---------------------- Page: 8 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
TECHNICAL REPORT ISO/ASTM TR 52906:2021(E)
Additive manufacturing — Non-destructive testing —
Intentionally seeding flaws in metallic parts
1 Scope
This document is intended to serve as a best practice for the identification and “seeding” of
nondestructively detectable flaw replicas of metal alloy PBF and DED processes. Three seeding
categories are described:
a) process flaws through CAD design;
b) build parameter manipulation;
c) subtractive manufacturing.
These include flaws present within as-deposited materials, post heat-treated or HIP processed
material, and those flaws made detectable because of post-processing operations. Geometrical aspects
or measurement are not the subjects of this document.
WARNING — This document does not purport to address all of the safety concerns, if any,
associated with its use. It is the responsibility of the user of this document to establish
appropriate safety and health practices and determine the applicability of regulatory limitations
prior to use.
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, Standard Terminology for Additive Manufacturing — General Principles —Terminology
ASTM B243, Standard Terminology of Powder Metallurgy
ASTM E7, Standard Terminology Relating to Metallography
ASTM E1316, Standard Terminology for Nondestructive Examinations
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/ASTM 52900, ASTM E7,
ASTM B243, ASTM E1316 and the following apply.
NOTE Terms for AM metal technology flaws are logically divided between PBF and DED categories of
processes.
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
coupon
piece of material from which a specimen is prepared
1
© ISO/ASTM International 2021 – All rights reservedPR OOF/ÉPREUVE
---------------------- Page: 9 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2021(E)
3.2
flaw classification
classification approach that provides a high-level system based on a primary characteristic or a
combination of characteristics
Note 1 to entry: Flaw classification may include similar flaw types that were created differently.
3.3
inclusion
foreign material held mechanically
Note 1 to entry: Inclusions are typically oxides, nitrides, hydrides, carbides, or combinations thereof being
formed due to contamination of the chamber gas, or already be present in the metal powder.
3.4
keyhole
type of porosity characterised by a circular depression formed due to instability of the vapour cavity
during processing
3.5
pore
inherent or induced cavity within a powder particle or within an object not connected to an exterior
surface
3.6
porosity
presence of small voids in a part making it less than fully dense
3.7
replica
intentional manipulated condition (flaw) to serve as the “seed” in a coupon (3.1) representing a known
flaw type
3.8
seeding
act of intentionally creating flaws, through CAD or manipulation of designated processing parameters,
that results in the placement of the anticipated replica (3.7) or the act of intentionally creating a replica
(3.7) through the insertion of a foreign object
3.9
sintering
process of heating a powder metal compact to increase density and/or improve mechanical properties
via solid state diffusion
3.10
surface-connected flaw
flaw that is in the body of the material but its boundaries reach to the material’s surface
3.11
unsintered
powder unaffected or affected but not fully consolidated during the additive manufacturing printing
process
4 Abbreviated terms
AM Additive Manufacturing
BM Base Metal
2
PROOF/ÉPREUVE © ISO/ASTM International 2021 – All rights reserved
---------------------- Page: 10 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2021(E)
CAD Computer-Aided Design/Computer-Aided Drafting/Computer-Aided Drawing
CNC Computer Numerical Control
CT Computed Tomography
DDC Ductility-Dip Cracking
DED Directed Energy Deposition
EB-DED Electron Beam Directed Energy Deposition
DR Digital Radiography (non-film)
EB-PBF Electron Beam Powder Bed Fusion
EDM Electrode Discharge Machining
GMA-DED Gas Metal Arc Directed Energy Deposition
HAZ Heat Affected Zone
L-DED Laser Directed Energy Deposition
L-PBF Laser Beam Powder Bed Fusion
NDE Non-destructive evaluation
NDT Non-destructive Testing
OEM Original Equipment Manufacturer
PBF Powder Bed Fusion
PSD Particle Size Distribution
RT Radiography Testing(film)
HIP Hot Isostatic Pressing
Tm Temperature melting point
WM Weld Metal
5 Typical AM flaws
Typically, additive manufacturing flaws in materials fabricated using optimised parameters have small
spherical flaws. Builds with less developed parameters may have a keyhole or larger angular pores.
However, high value components are often screened for flaws at a level determined by fracture analysis
such as those described below. The ability to create replicas to support the NDT detection capability
of complex structures is unique to additive manufacturing and can be considered when standard
inspection techniques are not adequate to ensure inspection reliability.
The occurrence of unintentional flaws during the additive manufacturing build is a possibility. The flaw
classification has been laid out in ISO/ASTM TR 52905 both L-PBF and DED. These flaws are: layer-
defects (horizontal lack of fusion), cross-layer (vertical lack of fusion), unconsolidated powder, trapped
powder, inclusion, layer shift, porosity and void; moreover, incomplete fusion, hole and cracking. It is
important to highlight that some DED defects are similar to those produced during the welding process,
while for L-PBF some defects are unique.
3
© ISO/ASTM International 2021 – All rights reserved PROOF/ÉPREUVE
---------------------- Page: 11 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2021(E)
In addition to flaws created to replicate naturally occurring anomalies, replicas may be generated to
serve as targets that can be used to understand x-ray, ultrasonic or other NDT capabilities (see Figure 1).
It is important that the fabricator of such replicas understands the physics of the NDT’s method for
which the flaws will be used. Capabilities demonstrations include detection in a specific complex
[5]
geometry such as a Representative Quality Indicator (RQI) according to ASTM E1817 , or detection
at a specific orientation relating to to the radiation beam. This replica is “seeded” intentionally around
the needs of the demonstrations. Ultrasonic sensing may find applicability through the technical
[3]
approach of ASTM E127 . Additionally, some of these seeding methods are implemented and detection
capabilities of seven NDT methods are assessed in ISO/ASTM TR 52905.
It has been found that replica size, orientation, and location can be designed into the build model to
create shapes (spheres, cubes, and rectangular prisms), sizes (lengths and diameters), and depths. An
example is shown in Figure 1 where embedded defects were designed into the step wedge with CAD
software, and since they are embedded with no powder removal vent, they are filled with unmelted
powder (unconsolidated powder/trapped powder).
a) CAD model showing the set of clusters and dimensions of the holes in the airfoil
4
PROOF/ÉPREUVE © ISO/ASTM International 2021 – All rights reserved
---------------------- Page: 12 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2021(E)
b) XCT scan displaying the visibility of the replicas seeded at different locations
and those that are not visible
Key
1 sets of holes containing 3 cluster
2 number of holes per cluster
3 holes dimensions per cluster
a
All 4 are visible.
b
⌀ 0,1 mm not visible.
Figure 1 — Model-designed replicas a), Computed tomography image of a generic airfoil built on
Ti-6Al-4V b)
With adjustments to the optimum build parameters, replicas can provide a desired off-nominal build
parameter. The shape of the replica can be planar, elliptical, rounded or another modelled configuration.
Two such off-nominal build parameters for seeding replicas are lowering laser power and increasing
the trace width larger than optimal.
Both of these types of replicas can be used to show the various NDT methods detection potentials. For
example, the computed tomography scans of the seeding replicas resulted in different yet detectable
material density changes created by each build parameter adjustment. The level of detail and different
views possible through computed tomography is shown in Figure 2 and Figure 3. The images in
both figures are not comparatives as those only illustrate differences in the detail when different
magnifications and methods are used.
Figure 2 — Computed tomography (CT) slice (left) with microscopy image at 50× (right): large
hatch spacing
5
© ISO/ASTM International 2021 – All rights reserved PROOF/ÉPREUVE
---------------------- Page: 13 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2021(E)
Figure 3 — Computed tomography (CT) slice (left) with microscopy image at 50× (right): lower
laser power
Replicas that are open to the surface are producible through the predetermined width dimension in the
model. Figure 4 shows a model used to determine the width capability of the L-PBF machine. These are
linear-type replicas which can have the powder removed. Figure 5 shows the surface in the as-built and
polished conditions.
Figure 4 — Open to the surface replica at different width dimensions
The left image is “as built” and right image is polished.
6
PROOF/ÉPREUVE © ISO/ASTM International 2021 – All rights reserved
---------------------- Page: 14 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2021(E)
Figure 5 — As-built coupon of the model in Figure 4
6 Procedure to produce replicas
The introduction of the AM process replicas can be accomplished through the changing of machine
parameters, feedstock conditions or mechanical procedures. The most representative methods are:
— seeding methods;
— AM process manipulation;
— mechanical procedures.
7 Seeding approaches
7.1 General
The following subsections provide seeding approaches for flaw replication using CAD insertion,
manipulation of off-nominal processing and mechanical machining.
7.2 CAD seeding
This is the simplest, most direct, and most accurate method to seed defects on AM parts. Defects of
specific geometries (cylinders, spheres, etc.) are added in the CAD design at specific locations. Some
defects are open to the surface allowing the powder to be released and some are closed geometries
which will have trapped powder. This method is used in ISO/ASTM TR 52905 where artefacts were
built with such seeded defects and then tested with several NDT methods.
The typical AM only flaws were intentionally seeded in the following manner: horizontal cylinders
open to the surface for layer-defects (horizontal lack of fusion), vertical cylinders open to the surface
for cross-layer defects (vertical lack of fusion), spheres and cylinders not connected to the surface for
unconsolidated powder or trapped powder. Inclusions are represented by inserting foreign material
into the surface open seeded defects. Table 1 shows more detail of how this is achieved, while Figure 6
and Figure 7 show examples of a design S1 and the corresponding build in Inconel.
Table 1 — General AM Seeding by CAD design
Defect Classification CAD seed into geometry
Layer defects (horizontal Add horizontally oriented geometrical features to the part geometry at desired locations
lack of fusion) in the part. Geometries can include but not limited to: cylinders, cuboids, etc. Ideally open
to the surface to allow the powder to be released.
Cross Layer (vertical lack Add vertically oriented geometrical features to the part geometry at desired locations in
of fusion) the part. Geometries can include but not limited to: cylinders, cuboids, etc. Ideally open
to the surface to allow the powder to be released.
Trapped powder or un- Add geometrical features to the part geometry at desired locations in the part. Geome-
consolidated powder tries can include but not limited to: spheres, short cylinders, etc.
Layer shift Add such deviations to the CAD design of the part.
Inclusions Using any of the layer and/or cross layer defects insert a determined material in such cavity.
7
© ISO/ASTM International 2021 – All rights reserved PROOF/ÉPREUVE
---------------------- Page: 15 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2021(E)
Key
Diameter Length
Region Description
mm mm
Cylinders in various orientations
1 Region 1 (Unconsolidated/trapped powder). Orientation 0,3 2,0
offsets of 45° and 90° relative to the first instance
Vertical cylinders interconnected 0,1, 0,2, 0,3, 0,4, 0,5,
2 Region 2 5,0
and open at both top and bottom 0,6 and 0,7
Spheres (Voids/porosity, unconsolidated/ 0,1, 0,2, 0,3, 0,4, 0,5,
3 Region 3 -
trapped powder) 0,6 and 0,70
Horizontal cylinders open at 0,1, 0,2, 0,3, 0,4, 0,5,
4 Region 4 2,5
the outside edge (Layer defects) 0,6 and 0,7
Horizontal cylinders open at 0,1, 0,2, 0,3, 0,4, 0,5,
5 Region 5 2,0
the inside face of the pentagon (Layer defects) 0,6 and 0,7
Figure 6 — Example design for S1 version of seeded defects
8
PROOF/ÉPREUVE © ISO/ASTM International 2021 – All rights reserved
---------------------- Page: 16 ----------------------
kSIST-TP FprCEN ISO/ASTM/TR 52906:2022
ISO/ASTM TR 52906:2021(E)
Figure 7 — An example of an S1 design build on Inconel
7.3 AM process manipulation replicas
7.3.1 General
This seeding is perhaps the more common approach when discussing the seeding of replicas (flaws)
and represents as closely as possible the potential naturally occurring flaws. Table 2 provides a list
of parameter adjustments that can be used for replica creation. It can be understood that the severity
of the replica may or may not match the target flaw. For example, the lack of fusion-type flaw can
vary considerably based on the cause and length of processing time. To compensate for severity,
multiple replicas using a range of the primary process manipulations provide a broader approach to
understanding demonstrable detection.
Many studies have been conducted through the manipulation of off-nominal processing parameters
such as defects – holes or slots, delays – laser on and/or off delays, trace width increase or decrease,
and laser power decrease or increase. Associated with these manipulations is the reference power
or optimal build parameters. Based on the outcome and end-use of the replica, the
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.