ISO/ASTM TR 52952:2023

TECHNICAL ISO/ASTM TR
REPORT 52952
First edition
2023-06
Additive manufacturing of metals —
Feedstock materials — Correlating
of rotating drum measurement with
powder spreadability in PBF-LB
machines
Fabrication additive de métaux — Matières premières — Corrélation
de la mesure du tambour rotatif avec la capacité d'étalement de la
poudre dans les machines PBF-LB
Reference number
© ISO/ASTM International 2023
© ISO/ASTM International 2023
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Published in Switzerland
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© ISO/ASTM International 2023 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Designation . 2
5 Methodology .2
5.1 General principle . 2
5.2 Powder selection . 3
5.3 Layer homogeneity evaluation . 3
5.4 Rotating drum . 4
6 Results and discussion .5
6.1 Spreadability . 5
6.2 Rotating drum analysis . 7
6.2.1 Experimental protocol . 7
6.2.2 Experimental results . 7
6.3 Discussion . 9
7 Conclusions .10
8 Additional data .11
9 Perspectives .12
Bibliography .13
iii
© ISO/ASTM International 2023 – All rights reserved

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
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different types of ISO documents should be noted. This document was drafted in accordance with the
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 261, Additive manufacturing, in
cooperation with ASTM Committee F42, Additive Manufacturing Technologies, on the basis of a
partnership agreement between ISO and ASTM International with the aim to create a common set of
ISO/ASTM standards on additive manufacturing, 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).
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iv
© ISO/ASTM International 2023 – All rights reserved

Introduction
Granular materials and fine powders are widely used in industrial applications. To support control and
optimize processing methods, these materials have to be precisely characterized. Characterization
methods are related either to the properties of the grains (granulometry, morphology, chemical
composition, etc.) or to the behaviour of the bulk powder (flowability, density, blend stability,
electrostatic properties, etc.). The complex behaviours of granular and powder materials have motivated
the development of numerous techniques to obtain reproducible and interpretable results. Many
industries are concerned in different fields: additive manufacturing, food processing, pharmaceuticals,
bulk material handling. This document is focused on Additive Manufacturing (AM).
Metallic powders are widely used in AM processes involving powder bed fusion (PBF-LB/M PBF-EB/M
etc.) or binder jetting. During such operations, successive thin layers of powder are deposited with a
blade or with a rotating cylinder. Each layer is then fused (most commonly melted) by an energy beam
or joined by an adhesive binder to build the parts. The layer thickness defines the vertical resolution
of the process; a thin layer leads to a better resolution. In order to obtain a thin layer, the powder is as
fine as possible. However, if it is assumed that among the cohesive forces, the Van der Waal forces are
[25]
predominant, it can be stated that as the grain size decreases, cohesiveness typically increases . This
increase in cohesiveness could have an impact on the spreadability of a powder.
The quality of the parts built with AM is thus directly influenced by powder flow properties.
According to ISO/ASTM 52900, spreadability is the ability of a feedstock material to be spread out in
layers that fulfil the requirements for the AM process; this includes the ability to form a flat powder-
atmosphere interface without waves and irregularities.
Visual observation of layer homogeneity is usually the only way for operators to assess the spreadability
of powders during the spreading of new layers. However, linking the powder characteristics to its
spreadability during the layer deposition beforehand can provide a more cost-effective way to classify
and select the optimal powder and layer deposition speed combinations.
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© ISO/ASTM International 2023 – All rights reserved

TECHNICAL REPORT ISO/ASTM TR 52952:2023(E)
Additive manufacturing of metals — Feedstock materials
— Correlating of rotating drum measurement with powder
spreadability in PBF-LB machines
1 Scope
This document provides an example of the relation between the characterization of certain macroscopic
properties of metallic powders and their spreadability in an PBF-LB/M AM machines.
This relation is based on a new technique combining measurements inside a PBF-LB/M machine and
image processing developed to quantify the homogeneity of the powder bed layers during spreading.
In this document, the flowability of five metal powders are investigated with an automated rotating
drum method, whose dynamic cohesive index measurement is shown to establish a correlation with
the spreadability of the powder during the layer deposition operation. Furthemore, the particule size
distribution (PSD) and morphology of each powder is characterized before testing by static image
analysis method (according to ISO 13322-1).
The general principle of the method is described in Figure 1.
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 https:// www .electropedia .org/
3.1
cohesiveness
physical powder behaviour relating to the degree to which the attractive forces between particles
exceed the average particle mass
Note 1 to entry: Cohesive powders are qualified as powders where the attractive force between particles exceed
the average particle mass
3.2
powder flowability
ability of a solid bulk material to flow
Note 1 to entry: Powder flowability is a function of multiple factors, and particularly powder size and distribution,
see also ISO/ASTM 52907.
© ISO/ASTM International 2023 – All rights reserved

4 Designation
In this document, five powders described in Table 1 are used:
Table 1 — Designation of powders
Denomination used in this
Common designation European spefication
document
1)
Scalmalloy® AlMgSc AlMgSc_Std
2)
Inconel® NiCr Mo Nb NiCr Mo Nb_Std
22 9 22 9
AlSi Mg AlSi Mg AlSi Mg_Std
7 7 7
Titanium Fine Ti Al V Ti Al V_Fine
6 4 6 4
Inconel® Fine NiCr Mo Nb NiCr Mo Nb_Fine
22 9 22 9
5 Methodology
5.1 General principle
The general principle for comparing rotating drum measurements with powder spreading in a
PBF-LB AM machine is described in Figure 1.
Key
1 AlSi Mg
2 NiCr Mo Nb (inconel® fine)
22 9
a
Good.
b
Bad.
c
Rotating drum.
d
PBF-LM machine.
e
Regular layer.
f
Irregular layer.
Figure 1 — General principle of comparing rotating drum measurements with powder
spreading in a PBF-LB AM machine
1)  Scalmalloy is an example of a suitable product available commercially. This information is given for the
convenience of users of this document and does not constitute an endorsement by ISO of this product.
2)  Inconel is an example of a suitable product available
...