Deutsche Bahn Explains How Mobility Goes Additive is Driving Railway 3D Printing

Our industry pays very little attention to rail, an industry that has its very own certification requirements. What’s more, due to the nature of these large vehicles, rail parts are very larges ones for 3D printing. And, to top it all off, these components are expected to last for years and sometimes decades under immense forces. Safety concerns are critical in rail, since a single failed part could spell disaster.

Despite these substantial obstacles, German rail giant Deutsche Bahn wants to industrialize 3D printing for maintenance and repair of its rolling stock and infrastructure. In doing so Deutsche Bahn is a true pioneer and Stefanie Brickwede is the wise and driven Additive Manufacturing leader behind the initiative.

To sum up, Brickwede faced an enormous challenge to do this within the current confines of 3D printing as a technology. She chose to look beyond those confines, however, and, instead of going it alone, she decided to reshape the market with partners. Mobility Goes Additive was founded to bring like-minded firms together so that they can collectively learn how to cost-effectively and safely industrialize metal and polymer 3D printing for rail and other transport. If the market isn’t there yet, let’s create it.

Mobility Goes Additive now includes BASF, Knorr Bremse, SKF, BigRep, McKinsey, ExOne, Ultimaker, Baker Hughes, Materialise, Stratasys, Beam Machines, 3Yourmind and Aircraft Philipp. As well as Deutsche Bahn, it features the Dutch, Italian, Austrian, and Swiss national railways and Hamburg’s Hochbahn public transport system. Mobility Goes Additive is potentially one of the most audacious and impactful things happening in 3D printing. If we can cost-effectively make large critical parts, it could fundamentally change our industry. Therefore, I had to reach out to the charismatic Brickwede to find out more.

3D printed wheel set bearing cover, pallet in the background for scale.

Brickwede started with Additive Manufacturing at Deutsche Bahn in 2015.

“We came to the conclusion that we wanted to do spare parts, but we couldn’t get the parts that we needed at all. Sometimes we couldn’t even get prototypes made of the things that we needed. One company can’t solve problems of this scale on its own. We decided to seek contact with other companies to see if we could perform a knowledge exchange… There were no real networks at the time that did what we needed to do. We, therefore, founded Mobility Goes Additive in 2016 with nine partners.” 

With an industry focused on aerospace, the requirements for rail in part size and cost were not being met. “People were using AM to solve different problems than the rail sector and the rail sector had its own requirements.” 

“In rail, we need to be punctual…spare parts need to be on time…and we have big spare parts. Some Directed Energy Deposition parts we have ,for example, are 27 Kilos. Many parts are welded, while cost is an issue, as is the need for our own certification. Especially for safety-relevant parts, we have to simulate 30 years of operation.”

A 27 Kilo 3D printed part.

Later on Mobility Goes Additive would expand far beyond rail and include automotive companies, for example. Now, Mobility Goes Additive has 120 members. Initially, “we needed experience with materials and information,” Brickwede said. Deutsche Bahn turned to experienced service bureaus like Hoffman and companies such as Knorr Bremse for their expertise in manufacturing. Uniquely Deutsche Bahn does not want to print parts, but rather shape and form the ecosystem for services to then print the parts for them. Brickwede is adamant that, “we don’t want to focus on the machine aspect.” 

A hand rail 3D printed with braille.

Deutsche Bahn and Mobility Goes Additive started with polymer 3D printing technologies, such as sintering and HP’s Multi Jet Fusion (MJF). For items such as handrails, they’ve also looked at fused deposition modeling, laser powder bed fusion (LPBF) and MJF. Meanwhile, they’ve evaluated various directed energy deposition (DED) technologies for repairing turbine blades and have looked at metal LPBF, as well. The company has even explored concrete printing. Some of the parts that they’ve made include bearing caps, parts in rail interiors, small items, mechanical components and parts for refits.

A 3D printed polymer fan wheel.

Certification is difficult, of course, and one aspect of that difficulty is that “as a maintainer and operator of trains, slight changes have considerable notification requirements.” Brickwede sees her task as “to help other companies understand the secrets of AM…help them get an overview and help them scale up very fast.” It is not all just technical, with “change management in organizations being a big part of implementing AM.” 

A 3D printed turbine wheel for a steam locomotive

Brickwede believes that, working in tandem with the consortium partners, safely relevant parts will be produced using all of the necessary suppliers and the TUV Sud. There is a considerable amount of testing and approval, which requires a great deal of time on an existing part using an approved material, particularly with individually certified components.

Sometimes the Mobility Goes Additive cooperation is much like a relay race, where one company will take care of 3D printing hundreds of test specimens. The others will then share the costs and take the project to the next phase. Research and learning are exchanged, which enables everyone to improve their capabilities. With the bearing caps, for example, Deutsche Bahn performed the certification before handing it off to a partner to conduct the dynamic load testing.

Brickwede said of the consortium, “We all save time. The industry is moving so much faster. You simply can’t design all of those things as just one company. We need to collectively develop norms, work together on education, and build up everything through a joint approach.”

Mobility Goes Additive has made significant progress over the past several years. So much so that they were asked to form a Medical Goes Additive division as well ,in order to advance the adoption of medical 3D printing. Brickwede explained the reason behind this more recent initiative by saying, “Our network is quite fast and we are known for being efficient and pragmatic” and the need for such a network for medical was “urgently necessary.”