AMSC Gaps Portal

Precursor Materials Section


Existing standards for flowability do not account for the range of conditions that a powder may encounter during shipment, storage, and the AM process.

R&D Needed: Yes. R&D is needed to measure and quantify flowability, especially with powder bed processing.

Recommendation: Standards are needed to address test methods which encompass the variety of flow regimes encountered in AM processes. Recommend completion of ASTM WK55610, New Test Methods for the Characterization of Powder Flow Properties for Additive Manufacturing Applications, (not specific to metal powders) which addresses dynamic flow, aeration, permeability, consolidation and compressibility test procedures using, for example, a powder rheometer. Recommend also completion of ISO/ASTM DIS 52907, Additive Manufacturing Technical Specifications on Metal Powder, which points to published standards for flowability tests along with consideration of how the state of the powder would affect the flowability measurement. See also Gap PC12 on precursor material flow monitoring.

Priority: Medium

Organization: ASTM F42/ISO TC 261, NIST, ASTM B09, ASTM E29

Status of Progress: Green

Update: As noted in the text, ASTM WK55610 and ISO/ASTM DIS 52907 are in development. Completion of those work items may partially but not fully address the gap.

7/18/2019, JM: ISO/ASTM 52907, Additive Manufacturing Technical Specifications on Metal Powder appears to be nearing publication

There is no known description of spreadability or standard for how to quantitatively assess powder spreadability.

R&D Needed: Yes. R&D is needed to measure and quantify spreadability, as well as to correlate powder characteristics with spreadability.

Recommendation: A standard should be created that guides the measurement of a powder’s spreadability. This standard may be comprised of a series of tests that together describe a powder’s spreading performance.

Priority: Medium

Organization: ASTM F42/ISO TC 261, NIST, universities, ASTM B09, ASTM E29

Status of Progress: Not Started, Or Unknown

Update: There are no ASTM standard test methods for spreadability.

While current standards for measurement of particle size and particle size distribution exist for powder metallurgy and can be leveraged for AM powders, the reliability and repeatability of different testing methodologies is currently unacceptable.

R&D Needed: Yes. Validation of various measurement techniques for reliability, repeatability, and correlation is required, possibly defining best measurement techniques for different build systems.

Recommendation: See R&D needed. For metal PBF, recommend completion of ISO/ASTM DIS 52907, Additive Manufacturing Technical Specifications on Metal Powder, which points to published standards for particle size analysis and discusses advantages and limitations of each referenced test method.

Priority: Medium

Organization: ASTM F42/ISO TC 261 JG 66, ASTM B09, ASTM E29

Status of Progress: Green

Update: As noted, ISO/ASTM DIS 52907 is in development as JG 66. Completion of this work item may partially but not fully address the gap.

7/18/2019, JM: ISO/ASTM 52907, Additive Manufacturing Technical Specifications on Metal Powder appears to be nearing publication

No standards exist giving users of AM criteria for use of a particular powder feedstock based on the powder morphology.

R&D Needed: Yes. R&D is needed to measure and quantify particle morphology.

Recommendation: Based on the results of R&D, a standard may be needed to define accepted test methods for powder morphology and criteria for determining acceptable powder morphology characteristics. Because powder morphology may affect powder flow, powder spreadability, and density of the AM built object, it could possibly be addressed indirectly by standards governing flow and spreadability requirements for a powder, taking into account the density of the powder. Recommend completion of ISO/ASTM DIS 52907, Additive Manufacturing Technical Specifications on Metal Powder, which points to published standards for describing particle morphology.

Priority: Low

Organization: NIST, ASTM F42/ISO TC 261 JG 66, ASTM B09, ASTM E29

Status of Progress: Green

Update: As noted, ISO/ASTM DIS 52907 is in development as JG 66.

7/18/2019, JM: ISO/ASTM 52907, Additive Manufacturing Technical Specifications on Metal Powder appears to be nearing publication

While existing powder metallurgy standards may be leveraged for AM use, they require tailoring for AM-specific situations. For example, sampling practices for reused powder that has been through an AM build cycle are needed to establish how to collect representative powder samples. These practices should take into account the variation caused by build exposure on powder in multiple locations.

R&D Needed: Yes, with respect to the re-use of powder during the build. See also Gaps PC7, PC10 and PC11.

Recommendation: Standards are needed for sampling of powders used for AM, with considerations for unique aspects of AM not considered in powder sampling standards for general powder metallurgy, including re-use of powder.

Priority: High.

Organization: NIST, SAE AMS-AM, ASTM B09, MPIF, ASTM D20 (for polymers), ASTM F42, ASTM E29

Status of Progress: Green

Update: SAE AMS7003, Laser Powder Bed Fusion Process was published in June 2018 and addresses this issue. For metals specifically, members of MPIF's Association for Metal Additive Manufacturing (AMAM) technical committee reviewed MPIF Standard Test Method 01, Method for Sampling Metal Powders (2016) and noted that challenges with standardizing powder sampling include variations for different powder alloy systems, additive manufacturing technologies, and the importance of powder purity to the application. ASTM B09 is currently reviewing the MPIF Std. Test Method 01. For polymers, there may be interest from ASTM D20 working in conjunction with ASTM F42.

No standards exist for measuring how to determine the presence and percentage of hollow particles and hollow particles with entrapped gas or their impact upon part properties and in-service performance.

R&D Needed: Yes. R&D is needed to establish the impact of hollow powder particles, if any.

Recommendation: Dependent upon R&D, a standard may be needed that specifies how to determine the percentage of hollow particles and hollow particles with entrapped gas in lots of metal powders. Testing may be needed to determine the level of hollow particles and hollow particles with entrapped gas that are acceptable without negatively affecting the properties and performance of finished parts. Recommend completion of ISO/ASTM DIS 52907, Additive Manufacturing Technical Specifications on Metal Powder and include measurement standards for powder internal porosity.

Priority: Low

Organization: For R&D: NIST, ASTM, America Makes, Oak Ridge National Laboratory, universities. For standards: ASTM F42/ISO TC 261, SAE, ASTM B09, ASTM E29

Status of Progress: Unknown

Update: None provided

7/18/2019, JM: ISO/ASTM 52907, Additive Manufacturing Technical Specifications on Metal Powder appears to be nearing publication

There is a need to develop AM process-specific metal powder specifications to ensure that a competitive supply of metal powder is available for procurement purposes. Further, vendors should be encouraged to use these industry powder specifications when testing their equipment and advertising final material properties.

R&D Needed: Yes. R&D is needed to determine the effect of powder parameters/characteristics on final part properties and on the suitability of a given powder for use in a given AM machine. Some of these powder parameters may include:

  • Particle Size Distribution
  • Particle Morphology
  • Flow Rate
  • Tap Density
  • Angle of Repose
  • Shear Stress
  • Chemistry
  • Specific Surface Area

Recommendation: Develop AM process-specific metal powder specifications to facilitate procurement of metal powders for use in AM machines. These specifications should describe the acceptable ranges of all relevant powder parameters that would impact the suitability of a given powder to be used in a given AM machine, and the effect it would have on final material properties.

Priority: Medium

Organization: ISO/ASTM, SAE AMS-AM, AWS, industry OEMs

Status of Progress: Green

Update: ASTM WK58219, New Guide for Additive Manufacturing - Feedstock Materials-Creating Feedstock Specifications for Metal Powder Bed Fusion, is in development. SAE AMS7001, Nickel Alloy, Corrosion and Heat-Resistant, Powder for Additive Manufacturing, 62Ni - 21.5Cr - 9.0Mo - 3.65 Nb has some of the parameters defined and was published in June 2018.

5/8/2019, LY: SAE has published the following metal powder material specifications for aerospace applications:

The following metal powder specifications for aerospace applications are under development:

4/4/2019, JM: A new powder specification AMS7013, Nickel Alloy, Corrosion and Heat-Resistant, Powder for Additive Manufacturing, 60Ni - 22Cr - 2.0Mo - 14W - 0.35Al - 0.03La was published in January 2019.   

Feedstock/precursor material can be sourced from either virgin polymer resin, recycled polymer resin, or a combination of the two. Recycled resin can be obtained from a number of different sources including in-house processed product of the same material which may not have met all the requirements when initially produced but is still functional, commercial recyclate from commercial sources, and post-consumer recyclate. Recycled feedstock, depending on its source and usage level, can introduce problems in the printing or end-use application due to the recyclate’s thermal/mechanical history, consistency and composition.

R&D Needed: Yes, to determine the acceptable limits and other constraints of incorporating reprocessed materials. This may be machine, material, and/or application specific.

Recommendation: Develop a general guidance document to address best practices in regard to sources, handling, and characterization of recycled materials. In some cases, such as medical and aerospace applications, more stringent guidelines may need to be developed such as identification of recycled material use.

Priority: Low

Organization: ASTM F42/D20, SAE AMS-AM

Status of Progress: New

Update: None provided

There are many classification systems and test procedures that are available and applicable to characterizing the feedstocks used for filaments or pellets. However, these are based on “conventional” processes and requirements and, in many cases, will need to be adapted to AM requirements and, in some cases, new, more specific systems and procedures may be required.

R&D Needed: Yes, to define the specific requirements and evaluate if these can be addressed by existing systems and procedures and, if not, to develop new ones.

Recommendation: Since this will be very dependent on specific materials and process requirements, existing documents need to be evaluated on a case-by-case basis, and, if necessary, new documents need to be developed. This is another aspect that needs to be considered by a possible ASTM F42 and D20 collaboration.

Priority: Low

Organization: ASTM F42/D20, SAE AMS-AM

Status of Progress: New

Update: None provided

There is a need to develop a standard for monitoring and sampling open liquid feedstock systems to ensure the consistent chemical composition and mechanical properties in the final AM part.

R&D Needed: Yes. R&D is needed to determine how much the viscosity can change before having a significant effect on the mechanical and chemical properties of the final AM part, how fast the change can happen and the frequency and method for sampling the open liquid feedstock system.

Recommendation: Develop a process-specific standard to indicate how often the liquid feedstock viscosity must be monitored throughout the feedstock’s lifetime (both in storage and in an open system).

Priority: Low

Organization: ISO/ASTM, Industry OEMs

Status of Progress: New

Update: None provided