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sts.components.contact.mr.placeholder Sebastian Webel
Mr. Sebastian Webel

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sts.components.contact.mr.placeholder Arthur F. Pease
Mr. Arthur F. Pease

Executive Editor English Edition

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Pictures of the Future
The Magazine for Research and Innovation
 

Additive Manufacturing

A Print-on-demand Manufacturing Plant

Lars Buchmann, an expert in 3D printing, extracts a freshly produced component from a metal printer at Siemens' Competence Center for Additive Manufacturing.

Additive manufacturing opens up huge opportunities for companies such as Siemens — especially in the service business. The Siemens Competence Center for Additive Manufacturing in Erlangen, Germany already produces individually adapted spare parts for the rail industry — quickly and cost-efficiently.

The two-story building on the Siemens campus in Erlangen, a university town just north of Nurnberg, doesn’t exactly look like a production plant for spare parts. It has no smokestack, no machine hall, and no assembly line. Instead, it has large windows, pleated blinds, and sterile-looking corridors.

But behind the veneered corridor doors, Siemens’ Mobility Division is ushering in a new era for spare parts. That’s because it is printing parts instead of breaking them out of molds or milling them from metal blocks. Thanks to its expertise in 3D printing, in 2014 the company was able to set up the Erlangen facility, which is called the Competence Center for Additive Manufacturing.  

Ideal for the Railroad Industry

In the plant’s showroom, Tina Eufinger, who is in charge of business operations, takes a black plastic armrest out of a glass display case. At first glance, it appears to be simply an ergonomic component of a customer’s streetcar, but it’s actually much more than that. The component is the result of a pilot project run by the plant in order to demonstrate the advantages of 3D printing for spare parts.

A laser prints a metal part at Siemens' Competence Center for Additive Manufacturing.

3D printing is booming, and the U.S. market research institute IDC expects the sector’s global sales to increase by 30 percent annually between 2016 and 2019, to more than $26 billion. I Innovations in 3D printing are also helping industries to develop a new level of flexibility, allowing, for example,  design studies and prototypes to be created faster and thus more cost-efficiently and series-printed parts to be used in the engines and control systems of airplanes.  3D printing is also in demand for the production of small numbers of components. In the rail industry, for example, where vehicles are often used for more than 30 years, 3D printing can make it possible to quickly and economically produce plastic or metal spare parts that are seldom required. The resulting operating experience can lead to technical improvements. “That’s why this project is ideal for the Mobility Division,” says Maximilian Kunkel, who is responsible for research and development at the center. “We can produce complex parts without having to worry about minimum volumes or the cost of tools.”

Thanks to additive manufacturing, ersatz components can now be produced and delivered in just a few days, rather than weeks or months.

The municipal utility company in Ulm, a city in southern Germany, is one of the beneficiaries. After the company launched a small fleet of Siemens Combino streetcars in 2003, several streetcar drivers said they would like to have additional switches on the driver’s seat armrest for the turn signals and for setting switch rails. But because the number of units required was very small, conventional manufacturing methods would have been impractical. However, thanks to a digital model of the armrest, it was possible to redesign it with cavities into which switches could be installed. The production process used laser sintering to build up each armrest layer by layer from a bed of plastic powder in a 3D printer. Wherever the laser struck the plastic powder, the powder briefly became viscous before it hardened into a mass. After the excess powder was removed, the printer’s operators had a blank that was ready for use after being dyed and having its surface treated.

In the past, whenever spare parts were not available streetcar operators had to wait for weeks or even months before expensive tools could be manufactured. Moreover, they generally had to purchase a certain minimum number of parts. Today, in many cases, spare parts can be produced at the Erlangen Competence Center and delivered to the customer within a few days. 3D printing can also be used to quickly and easily manufacture components with complex geometries, which would be very difficult to produce with conventional methods. In fact, 3D printing is often more cost-efficient than producing parts by other methods and then storing them until they’re needed.

Components characterized by complex geometries, which would be very difficult to produce with conventional methods, can be produced easily and quickly using 3D printing.

More than Just Armrests

For an additive manufacturing job, the Siemens Competence Center team first creates a CAD (computer-aided design) model. This is often much better than the original, due to the use of an optimized design, better material, and an improved printing process. To create the model’s physical counterpart, the associated data is transmitted to one of the center’s three printers, which produce the parts from plastic, aluminum or stainless steel. This step is followed by tests for handling, stiffness, and, most importantly, fire protection. To prevent fires, the Center almost exclusively uses a high-performance plastic characterized by low flammability.  “While other manufacturers are still testing their parts, we are standardizing the printing processes for metals and plastic so that we can guarantee properties such as functionality and service life in advance,” says Maximilian Kunkel. “Our colleagues at Corporate Technology in Erlangen and Berlin have been giving us support ever since our center was established.”

Following up on requests from Combino streetcar drivers, a small number of armrests were redesigned to include integrated switches. The armrests were printed using additive manufacturing.

It goes without saying that the 11-member team, which is headed by 3D printing expert Michael Kuczmik, manufactures much more than just armrests. For example, Tina Eufinger points to a motor-bearings cover. Unlike the original part, the printed component is hollow inside and filled with powder. This results in a number of advantages, including the fact that it reduces vibrations and thus helps to prevent wear. Another example is a custom-tailored switching cabinet for the first generation of ICE high-speed trains (manufactured between 1989 and 1993), which is no longer in large-scale production. The German railway company Deutsche Bahn rarely needs this component and cannot plan its requirements in advance. Printing the switching cabinet reduces train downtimes and thus saves a lot of money.

Printed spare parts also have other advantages. Because of their improved design, they usually require less material than original components and therefore weigh less. Moreover, they are generally more robust and have a longer service life. And in some cases, additional functions can be integrated as well. There are also some drawbacks, of course. For example, spare parts can’t be bigger than the printer’s printing chamber. However, a part can sometimes be assembled from smaller components— as was the case, for example, with a streetcar fender that consists of three parts. Because traffic accidents with streetcars usually only damage the right side of the fender, only about a third of this component generally has to be replaced.

Virtual Warehouse

The orders received by the new Competence Center are also increasing its virtual warehouse of spare parts, which now stores 450 digital models. No physical warehouses are needed to store these parts, and the manufacturing process doesn’t require any welding machines spewing sparks, let alone a foundry. Instead, Siemens’ Erlangen campus boasts plenty of green areas and a facility that combines a development lab with a manufacturing plant that quickly and cost-efficiently supplies spare parts for rail vehicles in a print-on-demand process.

Hubertus Breuer