So that it rolls again quickly

Text: Frank Rößler; Photos: Siemens Mobility — 16/02/2019

Rolling stock must roll in order to earn money. To simplify and accelerate this process even in difficult cases, Siemens Mobility GmbH relies on 3D printing of parts and tools. Stratasys supplied the technology to the Rail Service Center in Dortmund.

It is an ambitious goal that Siemens Mobility GmbH has set itself: 99 percent of the 82 multiple units of the Rhein-Ruhr-Express (RRX) are to be ready for operation over the next 32 years. The Siemens Desiro HC trains will be maintained and serviced at the RRX maintenance plant on a former marshalling yard in Dortmund-Eving.

A major challenge in the maintenance and repair of »rolling stock« (locomotives, wagons, motor coaches) is the availability and stock-keeping of spare parts, especially for older models. In the past, Siemens Mobility was often confronted with the problem that spare parts were supplied only after long waiting periods or in too large quantities.

The railway companies and groups only earn money with the vehicles when they roll in daily operation.

For this reason, according to Michael Kuczmik, Head of Additive Manufacturing at Siemens Mobility GmbH, the decision was made to produce the required parts digitally on site - parts for locomotives, railcars and equipment from the 3D printer.

The purchase of the appropriate hardware, the creation of the digital infrastructure, and the training of the em-ployees cost time and money, but the result is worth the effort. Instead of waiting weeks or even months for a spare part, components can be produced in a few days or hours, even if the price for the spare part is higher. The railway companies and groups, with their own track systems and rail vehicles, only earn money with the vehicles when they roll in daily operation.

Since September 2018, a Stratasys' FFM printer Fortus 450MC has been in operation in Dortmund, Germany, using the Ultem 9085 material. According to Kuczmik, this plastic is ideal for high-strength parts that can also be used in places where fire protection regulations apply: e.g. wall coverings and furniture parts that have been damaged by vandalism. In Dortmund, tools and fixtures are also manufactured: These can be used, for example, to pull a bogie frame across the company premises or to store Tablet-PCs used for maintenance.

According to Kuczmik, additive manufacturing also places special demands on Siemens Mobility employees. In addition to knowledge in maintenance, an affinity for engineering or design and CAD is important. Stratasys also provides support here, for example in the data conversion of design and manufacturing data and through workshops for employees.

Database with 800 spare parts

The print data for the multiple units of the RRX project are completely available in a database. However, parts for older makes can also be manufactured using additives: They are measured and converted into a digital model in the computer, which then develops in several iterations into a ready-to-use spare part. Within a few days, a part is available for which you would have had to wait several weeks.

The database currently offers information on over 800 different spare parts for »Print on Demand«, which can then be available within a few hours. So far, about 7,500 parts have been printed, supplying about 100 customers.

Over the next few years, Siemens Mobility intends to create a globally distributed printer network in the repair locations, so that spare parts are available on call, so to speak. This significantly eases the supply of spare parts, which is difficult to plan. Over time, spare parts can also be replaced by improved versions and thus meet any changed or tightened standards.

Load-bearing components before approval

In Dortmund, only plastics have been additively processed so far, but load-bearing components such as brake components or bogies subject to higher loads can also come from the 3D printer. This requires metallic materials that are currently being used in the Siemens Mobility Center of Competence (COC) for additive production in Erlangen. A brake component and a bogie frame for the Deutsche Bahn (German Railway Company) are currently on their way to approval. The goal is for these parts to be at least as robust and durable as the original.

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