AMSC Gaps Portal

Finished Material Properties Section

Updates have been made to the following gaps:

Many machine manufacturers offer general values for parts made from select materials in their machines. However, these values are not statistically validated and do not have the pedigree required for material design. Standards for thermal properties and minimum mechanical properties that also contain qualification procedures cannot currently be produced for AM materials, given the current state of knowledge, for the reasons stated above. Testing standards modified for use with AM parts that are designed/built to be inhomogeneous are also not available at this time.

R&D Needed: Yes.

Recommendation: Develop standards that identify the means to establish minimum mechanical properties (i.e., AM procedure qualification requirements) for metals and polymers made by a given AM system using a given set of AM parameters for a given AM build design. Developing these standards will require generating data that currently doesn’t exist or is not in the public arena. Qualification requirements to establish minimum mechanical properties for AM parts, both homogeneous and deliberately inhomogeneous, need to be developed.

Priority: High (Metals, Polymers); Low (Ceramics)

Organization: ASTM F42/ISO TC 261, SAE AMS-AM, AWS D20, CMH-17, MMPDS, NIST

Status of Progress: Green

Update: Work in progress is noted in the text.

5/8/2019, LY: SAE has published the following specifications which contain statistically based minimum properties for lot acceptance:

Two metals specifications are under development which will contain statistically based minimum properties for lot acceptance:

4/4/2019, LY: The AWS recently published a new standard on AM, AWS D20.1/D20.1M:2019 Specification for Fabrication of Metal Components using Additive Manufacturing.

Like many medical devices, medical AM parts must be cleaned of manufacturing residues and contact materials prior to packaging or final use. For patient-contacting (both direct and indirect) devices this cleaning must allow the device to pass tests for biological reactivity such as cytotoxicity and inflammation as described in ISO 10993. They should also ensure that AM materials such as powder are removed before use. Residues left on the parts may include but are not limited to cooling fluids or AM materials (powder or uncured monomer), that may be stuck within small geometric features or lattice structures. There are no standardized protocols or acceptance criteria to reproducibly measure and evaluate the cleanliness of a part with relevant, risk-based acceptance criteria.

R&D Needed: Yes. R&D is needed to establish standards which discern clean from uncleaned parts; specifically, to reliably distinguish unsintered, unmelted, and uncured material from the intended part

Recommendation: Develop standard test methods, metrics, and acceptance criteria for measuring cleanliness of complex 3D geometries that are based on existing standards but focus on AM-specific considerations. ASTM F04 already has work in progress.

Priority: High

Organization: AAMI, ASTM F04, ASTM F42/ISO TC 261, ISO, ISO/TC 150, ISO/TC 194

Status of Progress: Green

Update: As noted, ASTM F04.15 is working on WK53082 and WK60265.

Current standards and underlying infrastructure/technology are not mature enough to support the development of design allowables. For metallic additively manufactured material, a guideline was published by the MMPDS Coordination Committee describing an exploratory study for developing a metallic design allowable entitled “11-40. Guidelines for Emerging Materials and Technologies.” This guideline includes potential procedures to publish design allowables in a handbook and illuminates the gaps that would need to be addressed before AM could be included. For polymer based additively manufactured materials, an FAA sponsored research program is currently developing statistical procedures for allowables that will eventually be submitted to CMH-17 for consideration to be published in a new volume.

R&D Needed: Yes. Recommended R&D required to fill this gap includes the generation of a set of initial seed data and subsequent statistical analyses. The initial data may be developed via round robin testing and procedures to capture the multiple sources of variability inherent in AM materials and processes. These data should result from programs through public-private partnerships or government laboratories to ensure the sharing of information. Separate test programs must be developed for different material types as the distributions may not be the same across all materials (i.e., metallic, polymer, etc.). The generation of data and subsequent analyses will help define the minimum requirements and statistical methods necessary for additive materials.

Recommendation: Multiple developments must take place prior to generation and acceptance of design allowables for additive materials.

  • Material specifications: SDOs involved in developing and publishing material specifications should continue their efforts to adequately capture the relevant material parameters and minimum mechanical properties required for a specification. These specifications can be used in the future to support testing that will lead to the level of data needed to support design allowable basis values. Currently, the SAE AMS-AM Committee is actively developing specifications for lot acceptance of metallic and polymer additive materials. ASTM F42.05 may also have interest.
  • Data requirements and statistical analyses: Established organizations, such as MMPDS and CMH-17, should be involved in establishing the methodology required for deriving the allowables through a statistical process that takes into account the variability and parameters associated with additively manufactured materials. The MMPDS General Coordinating Committee, CMH-17 Executive Group, and/or other steering groups of organizations familiar with curating design allowable databases should develop guidelines on minimum data requirements and statistical processes. Although the key material/process parameters affecting allowables and in some cases the required test methods will differ, it is recommended to start with the currently available statistical analysis methods for metals and polymer composites as a baseline.
  • Test methods: Test standards organizations, such as ASTM/ISO, should provide recommendations on established test methods with special considerations for AM materials. If necessary, new coupon or component test methods should be developed.

Priority: High (Material Specifications); Medium (Data Requirements and Statistical Analyses): Medium (Test Methods)

Organization: ASTM F42/ISO TC 261, SAE AMS-AM, AWS, NASA, ASME BPVC, MMPDS, CMH-17, NIST

Status of Progress: Green

Update: At this time, no publicly available methodology for design allowables of additively manufactured materials has been identified. However, the three sections listed above (Material Specifications, Data Requirements and Statistical Analyses, and Test Methods) are all being addressed throughout multiple SDOs and other programs.

Material specifications are being generated by multiple SDOs at this time. SAE has a Data Management Sub-Committee currently defining guidelines to generate specifications minimum values for both metals and polymers. In addition to the work in progress noted in the text and gap statement, ASME's BPVC committee is looking at this. Regarding characterization methods for metals, the MMPDS coordinating committee has concerns that existing data requirements and statistical analysis methods are not sufficient. Their primary concern is the level of maturity of standards and specifications needed to ensure consistent properties. Polymer AM material test methods have similar issues; methods can either be adopted from plastic or polymer matrix composites methods, both of which may need modification.

5/8/2019, LY: One non-metals specification under development is tied to an AM qualification program with NCAMP (see MRO Network article, Creating an Easier Qualification Path for 3D Printing, which references SAE AMS7100)

FMP4 Recommendation 1 for Material Specifications also encompasses the SAE specifications listed under FMP1

4/4/2019, JM: In late Jan/early Feb 2019, SAE International released a finished material specification, AMS7004, Titanium Alloy Preforms from Plasma Arc Directed Energy Deposition Additive Manufacturing on Substrate, Ti-6Al-4V, Stress Relieved as well as the associated process specification, AMS7005, Wire Fed Plasma Arc Directed Energy Deposition Additive Manufacturing Process. In addition, 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.

The CMH-17 Volume for Additive Manufacturing kicked off in October 2018 in conjunction with the FAA. The new volume will cover non-metallic AM. A Coordination Group was formed to guide this activity with Working Groups in the areas of Testing, Data Review, Design & Analysis, and Materials & Processes. This volume, when published, will include design allowables for non-metallic AM materials. The first data set that will be reviewed for inclusion in this new volume is ULTEM 9085. Test Standards for Polymer AM – F42 has started a new work item for a standard guide that addresses recommendations for mechanical test methods for polymer AM. The guide is being developed this year in conjunction with the ASTM AM Center of Excellence and draws upon research conducted through America Makes and the FAA.

There is an inherent heterogeneity in the microstructure of metallic alloys made by AM that requires a standard for identification and quantification of the spatial variability of various microstructure features.

R&D Needed: Yes. NIST should help develop Calphad databases suitable for non-equilibrium solidification.

Recommendation: ASTM should develop a standard for characterization and acceptance criteria of AM microstructures (both identification and quantification).

Priority: Medium

Organization: NIST, ASTM

Status of Progress: Not Started, or Unknown

Update: Nothing started in terms of ASTM work.