ASTM F3571-22

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F3571 − 22
Standard Guide for
Additive Manufacturing – Feedstock – Particle Shape Image
Analysis by Optical Photography to Identify and Quantify
the Agglomerates/Satellites in Metal Powder Feedstock
This standard is issued under the fixed designation F3571; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2.2 ISO Standards:
ISO 9276-6 Representation of results of particle size analy-
1.1 This guide explains how to characterize the quality of
sis — Part 6: Descriptive and quantitative representation
metal powder feedstock to additive manufacturing (AM) rela-
of particle shape and morphology
tive to the powder shape using automated static or dynamic
ISO 13322-1 Particle size analysis — Image analysis meth-
image analysis by optical photography. This guide will de-
ods — Part 1: Static image analysis methods
scribe the method(s) to measure powder shape parameters that
ISO 13322-2 Particle size analysis — Image analysis meth-
can identify potentially detrimental powder characteristics and
ods — Part 2: Dynamic image analysis methods
specifically describe how to identify and quantify the propor-
ISO 14488 Particulate materials — Sampling and sample
tion of agglomerates/satellites and other irregularly shaped
splitting for the determination of particulate properties
non-spherical powder particles in a powder batch.
2.3 ISO/ASTM Standard:
ISO/ASTM 52900 Additive Manufacturing — General prin-
1.2 The values stated in SI units are to be regarded as the
ciples — Fundamentals and vocabulary
standard. No other units of measurement are included in this
standard.
3. Terminology
1.3 This standard does not purport to address all of the
3.1 Definitions:
safety concerns, if any, associated with its use. It is the
3.1.1 For definitions of terms pertaining to this standard not
responsibility of the user of this standard to establish appro-
otherwise listed in 3.2, Definitions of Terms Specific to this
priate safety, health, and environmental practices and deter-
Standard, reference should be made to ISO/ASTM 52900.
mine the applicability of regulatory limitations prior to use.
3.1.2 For definition of terms pertaining to this standard not
1.4 This international standard was developed in accor-
otherwise listed in 3.2, Definitions of Terms Specific to this
dance with internationally recognized principles on standard-
Standard,referenceshouldalsobemadetoTerminologyB243.
ization established in the Decision on Principles for the
3.2 Definitions of Terms Specific to This Standard: (Key
Development of International Standards, Guides and Recom-
Parameters)
mendations issued by the World Trade Organization Technical
3.2.1 aspect ratio, n—parameter name that has the formula:
Barriers to Trade (TBT) Committee.
aspect ratio5 x ⁄x
Fmin Fmax
where:
2. Referenced Documents
2 x = shortest distance between parallel tangents, and
Fmin
2.1 ASTM Standards:
x = longest distance between parallel tangents.
Fmax
B215 Practices for Sampling Metal Powders
B243 Terminology of Powder Metallurgy 3.2.1.1 Discussion—All parameter names in this guide are
given in ISO 9276-6. The parameter name may be different
depending on the manufacturer of the analyzer, but it could be
used if it has the same formula or a formula that correlates
This guide is under the jurisdiction of ASTM Committee F42 on Additive
directly with it. Aspect ratio is on a scale of 0 to 1. A 2 by 4
Manufacturing Technologies and is the direct responsibility of Subcommittee
F42.01 on Test Methods.
shape has an aspect ratio of 0.5.Acircle has an aspect ratio of
Current edition approved July 15, 2022. Published August 2022. DOI: 10.1520/
1. The parameter names B/L (breadth/length), and W/L aspect
F3571-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3571 − 22
individual size ranges. Some manufacturers provide a software feature
ratio are also used by some manufacturers for aspect ratio and
that can combine the image files measured on more than one objective,
correlate directly with x /x .
Fmin Fmax
which gives the ability to measure broader distributions than only one
3.2.2 convex hull, n—The outer boundary of a particle
objective would be capable of performing. The narrower the particle
image, as a rubber band would fit around the image as shown
distribution and the smaller the mean value, the more particles can fit on
inFig.1.withtheconvexhullgoingfrompointtopointaround
the moving stage providing a more representative sample.
the star.
4.3 Dynamic image analysis (DIA) by optical photography
3.2.3 ellipse ratio, n—this parameter is given as x /x ,
provides a wet or dry sample dispersion system that flows the
Lmin Lmax
where x and x are the lengths of the axes of the particle stream between a high-speed pulsating source of light
Lmin Lmax
Legendre ellipse, whose calculation is given in Appendix X2.
on one side and a digital camera on the other. Many size and
3.2.3.1 Discussion—The axes of the Legendre ellipse are shape measurements for each test can result in millions of
always perpendicular to each other, but the axes of aspect ratio
particle images and records for analysis.
(x /x ) are not. They approach being perpendicular the 4.3.1 The standard wet DIA method generally recirculates
Fmin Fmax
higher the aspect ratio is, and the maximum deviation from
the sample from a stirred dispersion module. Good method
perpendicular is for the shape of a square, where the aspect development practice would measure different amounts of
ratio is 1/1.414 (0.707), because the diagonal of a square (or
samples for different time periods to reach a combination that
any rectangle) is x . The ellipse ratio of a square is 1.0.
gives high reproducibility on consecutive samples
Fmax
3.2.4 solidity, n—parameter name that has the formula:
4.4 The dry feeder DIA design generally provides a vibra-
tory feeder to a drop point where the particles fall vertically
Area of the Particle⁄Area within the convex hull A ⁄ A
~ !
C
through the sensing zone. There are sometimes free-fall (grav-
3.2.4.1 Discussion—Solidity is on a scale of 0 to 1. This
ity fall) feeders plus an option for applying downward extra
“star” particle (Fig. 1) would have a solidity less than 1. A
variable air pressure to disperse agglomerates that might be
value of 1 represents a particle whose area completely fills the
present. The dry feeder systems do not re-circulate material,
areaoftheconvexhull.Asparticlesfilllessandlessofthearea
and the sample can be fed to the vibratory feeder continually,
of the convex hull, the solidity value decreases and approaches
and therefore, it can measure a much larger, more representa-
0.Somemanufacturersusetheparameternameconvexitytobe
tive sample than a recirculating wet feed system can.
the square root of solidity, which correlates directly with
solidity. [ISO 9276-6 defines convexity as the perimeter of the
5. Significance and Use
convex hull divided by the perimeter of the particle (P /P)].
C
5.1 Particle characterization, especially particle size
4. Summary of Guide
distribution, has been an important parameter for quality
4.1 There are two types of automated particle image analy-
control (QC) and research and development (R&D) in a very
sis: static and dynamic. In this guide, both types use optical
wide variety of industries and markets, anywhere a particulate
photography as the analytical technique. The operation of a
system is a final product or an intermediate constituent
static image analyzer by optical photography is described in
somewhere in the process. But size alone is not a sufficient
ISO 13322-1. The operation of a dynamic image analyzer by
morphological measurement to use to understand many factors
optical microscopy is described in ISO 13322-2. In both cases,
of the complete particle morphology of particulate systems and
dig
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