Additive manufacturing: new standard provides clarity

The manufacturers of 3D-printed implants, but also the suppliers as systemanbiers of additive manufacturing processes, must be able to guarantee that their products are safe and reproducible in the same quality. A new white paper from TÜV SÜD is designed to give them peace of mind. We spoke to Simon Schlagintweit and Julia Hoyer, who helped to produce it. 

Mr. Schlagintweit, why has there not yet been a standard on additive manufacturing in the medical technology sector?

Simon Schlagintweit: Published in 2009, ASTM F 2792 was the first additive manufacturing standard passed by ASTM International (formerly known as American Society for Testing and Materials). This standard primarily focused on the technology itself and thus had a different focus. The goal here was to first create the definition of AM. Over the next few years, subsequent standards answered a different set of questions. What materials can be used in AM and what are the materials requirements? How does the process work? What are the key features and core characteristics of this process?

Today we see the transition of the process to industrial application, not just as it pertains to the medical technology industry. This gave rise to ongoing standardization activities in additive manufacturing. One interesting aspect is that the ISO (International Organization for Standardization) and ASTM signed an agreement to increase their cooperation in the development of International Standards for additive manufacturing in 2011. The idea is to avoid the duplication of efforts and maximize knowledge and expertise on a global scale. At the time, it was something that had never been done before.

Medical devices are subject to strict controls and regulations. How does this affect the process?

Schlagintweit: Regulations specify the same requirements for all medical devices, regardless of the manufacturing method. The processes must always fulfill safety, reproduction, validation, and traceability requirements, which equally applies to AM, injection molding or any other technology used in this setting. Custom-made devices are a special case. This refers to a medical device made to meet the special needs of one individual. In the past, this meant true craftsmanship as there was a clear distinction between medical devices that are made via industrial manufacturing processes and custom-made products. That is why the latter had to meet different statutory requirements. These days, AM blurs the lines between the two because additive manufacturing enables the simultaneous creation of multiple different products. Yet they must meet the same requirements since they are made using the same industrial manufacturing process. This has prompted a heated debate regarding the classification of this situation. When is the device subject to all the requirements set out in the EU Medical Devices Regulation (MDR) and when do only the requirements for custom-made devices apply?

Julia Hoyer: Basically, medical devices are always subject to laws and regulations, which apply to both additively manufactured and conventionally manufactured medical products. The laws and regulations state that the latest information pertaining to a new standard must be addressed in a timely and relevant manner. This doesn’t necessarily mean that all companies will be able to achieve one hundred percent implementation, but they must include these guidelines in their design considerations. If a company cannot meet all the requirements, it must substantiate why certain aspects are not applicable to the product. As a Technical Inspection Association, we review and take a closer look at the situation. However, if a company has created a better solution for its device as it relates to the general safety and performance requirements and can justify its alternative approach to the applicable statute and regulations, it will be met with approval.

What is your experience when you visit companies? Do they understand and implement the relevant standards accordingly? Or are there moments when you must request adjustments and changes?

Schlagintweit: That depends on the company's focus. Some companies specialize in rapid prototyping or B2C, meaning the customer wants the company to quickly fabricate a scale model of a physical part or assembly, making certain characteristics and requirements not as imperative. Here, standardization and certification have different significance.

How do you develop a new standard?

Schlagintweit: To submit a proposal for a new standard, you can approach multiple committees including DIN (Deutsches Institut für Normung e.V., the German national organization for standardization) or ISO. For example, the Technical Committee 261 oversees additive manufacturing, while the TC 150 is all about implants. The two groups have recently created a “joint working group” that is developing a standard for additive implant manufacturing. The working group has many heated discussions and documents all events. This starts the process, which is followed by annotation phases and voting procedures. It can take months to years before the finished standard can be published.

Is there an automated mechanism that regularly reviews the standards?

Hoyer: Yes, there is. For example, DIN e.V. reviews norms and standards at least every five years after publication and specifications at the latest every 3 years. ISO or DIN define the respective specifications, for example.

Do you think additive manufacturing will experience even more growth in the medical device industry in the future? Could this possibly replace traditionally manufactured medical devices?

Schlagintweit: I don't think this will replace conventional medical devices. You must always assess whether AM is the right process to create a particular medical device. Admittedly, in conversations with customers, I notice that more and more think it is the best choice.

Hoyer: That being said, we emphasize that this is not just a matter of converting an existing design to produce it with additive manufacturing. It actually means adapting the construction and the design, which is a factor many underestimate. It’s not as easy as buying a printer and switching over the process. The first challenge is to rethink your overall product design. The process opens new opportunities, especially when it comes to custom-made devices. Think of tumor patients who need customized bone implants that cannot be made in industrial batch production.

What feedback did you receive on your white paper?

Schlagintweit: We have already received positive feedback though I would also welcome critical/constructive feedback and comments because it is the only way that allows us to promote continuous improvement of standards and foster innovation in technology!