Metal Additive Manufacturing: Why standards lay the foundation for continued industry growth

As the metal Additive Manufacturing industry evolves towards widespread use for series production, the need for globally-recognised standards is also increasing. In this article, Prof Dr-Ing Christian Seidel, Chairman of ISO Technical Committee (TC) 261 ‘Additive Manufacturing’ and Member-at-Large on the Executive Committee of the ASTM F42 ‘Additive Manufacturing’ Committee, outlines why standards are so important, presents an overview of the current AM standards ecosystem, and highlights current key areas of standardisation activity. [First published in Metal AM Vol. 7 No. 1, Spring 2021 | 20 minute read | View on Issuu | Download PDF]

Fig. 1 Market potential of the prototyping, tooling and Direct Manufacturing application of Additive Manufacturing (qualitative, size indicates market potential)

In recent years, more and more organisations have started to develop standards for Additive Manufacturing. This is because the size of the industry has now reached a level where effective business is only possible on the basis of a reliable and complete set of accepted industry standards.

I write this article as Chairman of ISO Technical Committee (TC) 261 ‘Additive Manufacturing’ and Member-at-Large on the Executive Committee of the ASTM F42 ‘Additive Manufacturing’ Committee. These two committees have been cooperating since 2011 to provide the Additive Manufacturing industry with the needed standards. In this article I intend to outline recent progress and some fundamental aspects of standards. An overview on the organisation of ISO/ASTM joint standard development is provided, and the current strategic direction of standardisation is introduced.

What readers will discover is that, on the one hand, a powerful structure for international standardisation has been built up in recent years and is now available and, on the other hand, a large number of relevant standards is already available.

The need for standards in Additive Manufacturing

The Additive Manufacturing industry as a whole is rather niche and still in its infancy. However, the market has recorded high growth rates in recent years and has, therefore, received a lot of attention. A comprehensive set of industry standards is a requisite if this is to remain the case. Most recently, Additive Manufacturing technologies have gained significance as production technologies. Originally, the only field of application for AM was the time-efficient production of prototypes – also known as Rapid Prototyping. During the last five to ten years, a significant increase in applications for direct part production can be observed, especially in the aerospace and medical industries, as well as in general engineering.

This extension in application from prototyping to manufacturing is crucial to continue the growth rates seen in recent years, because prototyping often does not require the production of more than ten parts. However, to achieve a double-digit compound annual growth rate over the coming years and to further mature Additive Manufacturing technologies, it is necessary to identify and exploit business cases within small- and medium-scale series. As a result, machine and material sales will increase and Additive Manufacturing technologies will further establish themselves as production technologies.

Fig. 1 is intended to show, qualitatively, that the market potential for direct manufacturing is many times greater than that of prototyping and tooling. In addition, the growth potential in prototyping applications has largely been exploited at this point. Standards can be seen as a key enabler for the transition towards direct manufacturing; economic utilisation of AM processes in a production environment on an increasing scale simply isn’t possible without a comprehensive set of industry-specific standards.

The role of standards

The foremost aim of international standardisation is to facilitate the exchange of goods and services by eliminating technical barriers to trade. Standards serve as a common language that promotes the flow of goods between buyer and seller and protects their general welfare. Typical benefits of standardisation in the field of AM comprise:

  • Providing a common language (e.g., terms & definitions)
  • Assisting users with the assessment of different AM processes, resulting in the use of appropriate technology for specific product demands
  • Specifying requirements for processes, materials, design, and test methods
  • Standardising data formats, structures and metrics for AM models
  • Providing guidance on environment, health and safety concerns
  • Providing qualification schemes and defining requirements for personnel qualification
  • Standardising the process chains of AM technologies, securing functionality, compatibility and easing the design of efficient global and local supply chains
  • Communicating guidance and possible courses of actions
  • Documenting best practices.

Thereby, standards can help accelerate the adoption of new technologies and ease international collaboration. In the field of Additive Manufacturing, standards are a key enabler for the upscaling of the industry. However, standards should not be confused with laws and regulations; compliance is not compulsory (Fig. 2).

Fig. 2 Simplified ranking between laws, regulations, standards and guidelines

Ecosystem of international standardisation for AM

We are currently seeing a lot of standardisation activity, with various Standards Development Organisations (SDOs), certification bodies and associations being active in the field of AM. Fig. 3 provides a partial overview of this, but, nevertheless, only contains an extract of the worldwide activities. In general, a distinction can be made between standardisation activities that are intended to bring national added value: for example, in Germany, the German Welding Society, versus those intended for international recognition, such as ISO/TC 261 and ASTM F42 on Additive Manufacturing.

Fig. 3 Selected worldwide standardisation activities covering selected associations, certification bodies and SDOs. Arrows indicate formal cooperation. TC =Technical Committee; FA & NA = German for Committee; AM = Additive Manufacturing; EHS = Environment, Health and Safety; PSDO = Partner Standards Developing Organization; SDO = Standards Development Organizations (Source USA: AMSC Standardization Roadmap for Additive Manufacturing, Version 2.0, June 2018, based on a graphic developed by Joerg Lenz, former chairman of ISO TC261)

Furthermore, it makes sense to picture SDOs, certification bodies and associations within one umbrella, as there is a close link between these organisations. SDOs intend to develop technical regulations, which are then used by certification bodies to develop their certification procedures. Associations serve as the voice of the industry and provide both SDOs and certification bodies with information on the needs of their members.
In addition, standards only become of value when applied in industry. For that reason, Associations also serve as information and marketing channels for SDOs as part of a win-win situation.

In Fig. 3, the text blocks are marked with logos or flags that indicate the origin of the above groupings. The upper row shows the situation for Germany, where, primarily, the DIN and VDI are promoting standardisation in the area of AM. The middle row contains information on AM-relevant committees within the ISO organisation and the EU. The bottom row gives an insight into the standardisation landscape in the USA.

Introducing ISO/TC261

ISO, the International Organisation for Standardization, is a legal association, the members of which are the National Standards Bodies (NSBs) of some 140 countries – organisations that represent a country’s social and economic interests at the international level. ISO is supported by a central secretariat based in Geneva, Switzerland. In total, 23,413 international standards have been published by ISO as of October 2020, covering almost all aspects of technology and manufacturing. In 2020, 792 Technical Committees (TC) and subcommittees took care of standards development.

ISO TC261 is the technical committee within ISO on Additive Manufacturing. The scope of ISO TC261 is stated as, “Standardisation in the field of Additive Manufacturing (AM) concerning their processes, terms and definitions, process chains (Hard- and Software), test procedures, quality parameters, supply agreements and all kind of fundamentals.”

As of Q1 2021, ISO TC261 had twenty-five participating and eight observing members. Moreover, nineteen ISO standards were published, with an additional 31 were under development, most of which were joint ISO/ASTM standards. The most current information on published documents and ongoing work can be found at [1].

The structure of ISO/TC261 is characterised by Working Groups (WGs). As of Q1 2021, five Working Groups are available (Table 1). Currently, there is no WG5 – this gap is a result of a renumbering of so called Joint Working Groups (JWGs), which operate as a collaboration between two committees to mutually benefit from domain-specific expertise. Cooperation with other ISO/TCs has always been in the DNA of ISO/TC261 in order to meet application-specific AM needs. For this reason, the three JWGs shown in Table 1 have been established so far. In addition, around twenty formal liaisons were established with other ISO/TCs and relevant organisations in order to ensure exchange of information and a foundation for collaboration.

Table 1 ISO/TC261 ‘Additive Manufacturing’ – Working Groups and Joint Working Groups

Introducing ASTM F42

ASTM International is a Standards Development Organisation (SDO) and has been developing standards for more than ninety industry sectors since 1898. Currently, there are more than 12,800 ASTM standards operating globally [2], including 140 technical committees with more than 30,000 volunteer members representing more than 140 countries.

The ASTM F42 Technical Committee on Additive Manufacturing Technologies was formed in 2009. F42 is one of the technical committees within ASTM and it passed the thousand member mark in late 2020, with over twenty-eight countries contributing actively to its AM standards development work. The F42 committee meets in person twice a year, typically in conjunction with ISO/TC261, and there have been twenty-two meetings since 2009, ten outside of the US. To date, F42 meetings continue to attract large industry interest and participation from the AM community, including representatives from government agencies, industries, academia and trade associations. Besides the biannual meeting, members within each working group attend regular conference calls to progress standard development.

Generally, each main committee in ASTM is composed of subcommittees that address specific segments within the subject area covered by the technical committee. F42 follows the same structure and is composed of the subcommittees listed in Table 2. The general set-up is, intentionally, similar to the structure of ISO/TC261.

Table 2 F42 Additive Manufacturing subcommittees

ISO/ASTM collaboration

In 2011, ISO and ASTM signed a cooperative agreement to govern the ongoing collaborative efforts between the two organisations to adopt and jointly develop international standards that serve the global marketplace in the field of Additive Manufacturing. The purpose of this Partner Standards Developing Organisation (PSDO) cooperative agreement is to eliminate duplication of effort while maximising resource allocation within the industry.

ISO/TC 261 and ASTM F42 are striving for ‘dual logo’ standards, ‘ISO/ASTM’-standards, that reflect a strong international consensus, allowing these standards to be used by companies worldwide. For the development of these joint standards, a ‘Three Level Approach’ has been developed, as shown in Fig. 4.

Fig. 4 The three-level approach of joint standard development between ISO/TC261 and ASTM F42

Ideally, generic and generally relevant ‘general top-level AM standards’ are developed in all subject areas at the beginning. Building on this, the development of ‘category AM standards’ should then begin, which apply to specific material or process categories, for example. ‘Specialised AM standards’ can then be developed for specific needs, building on the first two levels. It is important to highlight the ‘etc.’ – boxes in Fig. 4: since ISO/TC 261 and ASTM F42 aim to serve all industries’ current needs, the topics mentioned in the chart are meant as examples. The fact that technologies are developing rapidly, as the latest research results on smart parts shown in Fig. 5 demonstrates, means that standardisation must also be organised in an adaptable manner and driven by market demand.

Fig. 5 Demonstrator for a sensor-integrated smart part, built on a modified PBF-LB machine, courtesy Fraunhofer IGCV, Augsburg, Germany

The objectives of this collaboration can be summarised as follows:

  • Deliver ISO/ASTM-standards needed for industry
  • Consider worldwide standard needs
  • Deliver comprehensive sets of industry-specific standards
  • Cooperate and collaborate with relevant players in the AM industry
  • Serve as a ‘melting pot’ for the international AM community.

As of Q1 2021, there are now sixteen published joint ISO/ASTM AM standards [3] and 50+ joint standards [4] under development. For 2021, projects will increasingly address standardisation requirements of the automotive, construction and space industries, as well as other sectors such as oil/gas, etc. To meet standards demand from the automotive industry, Joint ISO/TC 261 – ASTM F42 Group ‘Qualification for AM processes in automotive applications’ was established in late 2020.

Introducing terminology standard ISO/ASTM 52900

When a new technology emerges, the first topic to which technical regulations are devoted is always terminology. This is established practice, since without a common terminology, or language, no in-depth technical exchange is possible. For this reason, terminology was also addressed by the first standardisation project in the field of Additive Manufacturing. In 2015, the result was published as ISO/ASTM 52900 ‘Additive Manufacturing – General Principles – Terminology’. Within ISO/ASTM 52900:2015, for example, seven process categories were introduced to classify AM technologies (Fig. 6). Furthermore, new terms emerging from the further work in Additive Manufacturing will be included in upcoming amendments, such as the Draft International Standard update as of 2020.

Fig. 6 Additive Manufacturing process categories defined by ISO/ASTM 52900:2015 (Courtesy Fraunhofer IGCV)

Spotlight on selected international Additive Manufacturing standards

As mentioned above, currently nineteen standards have been published by ISO/TC261. Fig. 7 allocates selected documents in a generic AM process chain and teasers in which areas the international standards could be applied. The following is a brief introduction to the standards published in 2020.

Fig. 7 Selected standards put into perspective with regards to generic AM process chain

Material Extrusion (MEX)

With ISO/ASTM 52903-1:2020 and ISO/ASTM 52903-2:2020, the first international standards on Material Extrusion processes are now available. Part 1 covers feedstock material and Part 2, corresponding process equipment. This is a significant milestone to enable extrusion-based technologies to further gain market relevance.

System performance and reliability

ISO/ASTM 52941:2020 covers an acceptance test for Laser Beam Powder Bed Fusion (PBF-LB) machines for metallic materials for aerospace application. Therefore, it eases and supports certification procedures in the aerospace industries. Though being specifically developed for the aerospace industry’s needs, it can also be used in other industries, if suitable.

Data format

ISO/ASTM 52915:2020 is an international standard covering a specification for the Additive Manufacturing File Format (AMF), version 1.2. AMF is a standardised open data format specifically designed for the needs of Additive Manufacturing processes. It is technically more suitable than the quasi-standard format STL, by far, but has not yet gained industrial significance. With the 2020-released AMF version 1.2, described in ISO/ASTM 52915:2020, this is likely to change.

Qualification principles for Additive Manufacturing

As Additive Manufacturing technologies are increasingly used in production, there is a demand for qualified staff. For that reason, six international standards are currently under development within ISO/TC 261 to provide qualification principles for several profiles. ISO/ASTM 52942:2020 is the first published international standard of a series of qualification principle standards to be followed in 2021. ISO/ASTM 52942 covers requirements for machine operators of PBF-LB machines and related equipment used in aerospace applications.

Design

ISO/ASTM TR52912:2020 is an international Technical Report that provides an overview on functionally graded Additive Manufacturing. As an ISO/ASTM Technical Report (TR) it is an informative and non-normative document. An example multi-material part is shown in Fig. 8.

Fig. 8 Multi-material part, consisting of tool steel (1.2709) and a copper alloy (Courtesy of Fraunhofer IGCV)

How to get involved?

The standardisation network is constantly growing and welcomes new interested experts. There is no defined group of experts that develops standards for everybody – it must be demand-driven and “for users, by users”. Fig. 9 shows a flowchart of how interested parties can get support if they are looking for a standard or wish to develop a standard.

Fig. 9 How to get involved? [1]

Author

Prof Dr-Ing Christian Seidel
[email protected]

Prof Dr-Ing Seidel is Chairman of ISO/TC261 ‘Additive Manufacturing’, Member-at-Large, ASTM F42 ‘Additive Manufacturing’ Executive Committee, Professor Manufacturing Technologies and Additive Manufacturing at Munich University of Applied Sciences, and Head of Additive Manufacturing at Fraunhofer IGCV.

References

[1] https://committee.iso.org/home/tc261

[2] www.astm.org

[3] www.iso.org/committee/629086.html

[4] https://committee.iso.org/home/tc261

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As well as an extensive AM industry news section, this 204-page issue includes articles and reports on:

  • Optimised thermal management in semiconductor fabrication using AI-enabled generative design and Additive Manufacturing
  • Forging a process for mass customisation via metal Additive Manufacturing
  • Bringing it all together: How Materialise is integrating manufacturing and software expertise to shape AM’s future
  • Pedal to the metal at the Digital Manufacturing Centre: Redefining what’s possible for AM in hypercars and beyond
  • The future is Additive Manufacturing – if we take a more holistic view of the design opportunities
  • Building a case for radical collaboration plus quality standards: The pathway to growing the AM industry
  • Distributed manufacturing: Old concept, new relevance, new technology?
  • Design for Additive Manufacturing: A workflow for a metal AM heat exchanger using nTopology (BJT)
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