Breaking the certification barrier in aerospace AM

The aerospace industry is a hotbed for manufacturing innovation and has been an early and frequent adopter of additive manufacturing (AM). However, while 78% of aerospace companies use AM for prototyping, only 18% are currently using the technology for flight-ready end part manufacturing.

The barrier to end-part AM isn’t an issue of application suitability, but one of standardization and certification. Materialise worked with aerospace suppliers and original equipment manufacturers (OEMs) to enable AM production in a wide range of aircraft parts through software and manufacturing solutions, from structural components, such as 3D printed turbine blades for GE’s GE9X jet engine, to aircraft cabin interiors where elements need to be functionally and aesthetically perfect. In the Airbus A350 ecosystem alone, we currently print around 100 different part numbers, totaling an estimated 26,000 parts per year.

Certification methods for aerospace AM

There are two overarching methods for the certification of flight-ready parts. In some cases, companies develop specific certification methods where the OEM or supplier provides tested parameters and processes for AM production to ensure parts meet their standards. Certification can also be achieved through data collected by AM companies and shared with design organizations (DOAs) for analysis and qualification to ensure part performance meets specifications for flight-ready parts.

Using Airbus as an example of the first method, the company develops its own qualification process where they own the production and performance data and set parameters for the AM process based on their own experience and analysis of AM builds. Last year, through this process, they reached an important milestone in receiving Airbus qualification to manufacture flight-ready parts using laser sintering technology in addition to a previous certification for fused deposition modeling (FDM) printing. While several companies implement this qualification process to maintain a competitive edge and ownership of the process, others with less AM experience may look to industry experts for guidance on part and process qualification.

In those cases, the AM industry can support more robust qualification methods by collecting and analyzing performance data from their own builds and providing this data to DOAs to guide the development of broader, more standardized certification standards. With sufficient performance and process data, these organizations can accurately predict and assess mechanical properties of parts produced with AM to ensure they meet requirements for flight-ready parts. Both approaches can advance the use of AM in aerospace, but there’s more work to be done before AM can reach its full potential in the industry.

Barriers to widespread AM adoption

The most significant barrier to widespread adoption of AM in flight-ready parts is the inability to consistently qualify and demonstrate part performance. Specifically, lack of standardized performance data for components produced with AM has led to varying views on data needed to qualify AM parts and processes, due in part to the lack of a standardized approach – industry must continuously reinvent the wheel when working to demonstrate consistency.

AM’s relative youth compared to other manufacturing technologies also means there isn’t as much production data available to prove parts built to a given specification will always behave in a certain way and therefore meet the safety criteria relevant to their functionality. However, there’s room for improvement in the approach to specifications to create less stringent qualification processes for low-criticality parts and more consistent processes for critical part qualification where there’s more significance behind part performance.

In low-criticality parts, regional agencies have taken steps to facilitate adoption of AM. In 2020, the European Union Aviation Safety Agency (EASA) issued a memorandum which recognized a distinction between low- and high-criticality parts and encouraged DOAs and production organizations (POAs) to collaborate on part qualification for the former.

This collaborative approach is equally applicable to critical part qualification, but given the importance of these parts, the process must be more stringent, and manufacturers must demonstrate parts will always meet performance and safety criteria. Without standardized processes for qualifying these parts, different DOAs often have varying views on the data needed. For a single part, it’s not uncommon for different DOAs to request entirely different sets of validation data. This creates a need for the AM industry to continuously adapt to varying criteria and additional barriers to the technology’s use in flight-ready parts.

Overcoming barriers to AM production

In the short term, we can look to low-criticality parts as the unsung heroes of AM in aviation and an area for exploration of new applications within the industry. Using valuable performance data from low-criticality part production, DOAs can validate AM parts in a safe environment, compile data on various processes, and eventually inform future standards for manufacturing critical, flight-ready parts with AM.

For POAs, there’s an emphasis on demonstrating reliability, repeatability, and delivering data for DOAs going beyond minimum requirements reached. Materialise recognized having been an EASA 21.G-certified Production Organization since 2015, they held a useful back catalog of information on part performance. In printing more than 700 different part series for the aerospace industry, we’ve been able to establish a data lake showing how design choices impact mechanical properties, part density, and tensile strength, but also – alongside process control documentation – results through time. The latter’s a crucial ingredient for DOAs looking for consistency. It’s our intention to keep this data lake dynamically updated, an ever-growing resource to support robust decision making.

DOAs have an important role to play, too. By working with each other, and with POAs taking this kind of proactive approach to data provision, a standardized part qualification process becomes a realistic destination.

Looking to the future, this could be addressed through introduction of industry standards for 3D-printed parts, outlining data and performance parameters for part qualification that work for everyone throughout the industry.

For those within the AM industry, further collaborative work will also be essential to fine-tune the processes and materials used for metal parts if AM is to play a more substantial role in critical component production. By ensuring data is collated and analyzed throughout production to demonstrate the performance of stabilized production processes, AM stakeholders can add to the repository of available data for regulators, organizations, and manufacturers to support informed, robust decision making. For monitoring, analysis and optimization, AM software platforms connecting the digital thread from design to delivery will prove to be an essential source for monitoring, analyzing, and optimizing part performance and AM processes.

These collective initiatives represent a significant undertaking, but one worth addressing given the advantages AM has demonstrated for aerospace suppliers, OEMs, and maintenance, repair, and overhaul (MRO) businesses. Essentially, the key will be collaboration between the aerospace and AM industries to identify and standardize part qualification and identify the aerospace applications where AM can provide the greatest value. The potential for AM to become a mainstream, transformative tool for aerospace already exists, and with initiatives already in place to support this goal, it’s only a matter of time before it’s achieved.

Materialise

About the author: Erik de Zeeuw is aerospace market manager at Materialise and can be reached at Erik.deZeeuw@materialise.be.