After the Kaprun cable car fire in November 2000 and the fire in the sleeping car of the DB night train from Paris to Munich in 2002 (two of the worst train fire disasters in Europe), calls for flame-retardant parts in rail vehicles became ever louder. Railroad operators and federal railroads wanted to respond with components made of certified materials to increase fire protection in trains. The European railroad standard EN 45545 was then introduced in 2013 and replaced the existing national standards from 2016 after a transitional phase.
EN 45545 brought significant strides forward in flame retardancy and, in the long term, greater safety. However, our world and especially our newer technologies are constantly evolving, meaning that EN 45545 can sometimes prove problematic for many parts manufacturers and railroad operators. Additive manufacturing in particular, which is often used for spare parts and short runs, is faced with an inadequate certified material supply. Railroad operators are therefore faced with a major challenge: the right partner with the right material is needed! The Austrian Federal Railways (ÖBB) found this partner in the material manufacturer and service provider TIGER Coatings, which was able to manufacture components from flame-retardant materials using 3D printing. So let’s take a closer look at this success story!
The flame-retardant material from TIGER Coatings complies with the EN 45545 standard (photo credits: TIGER Coatings)
EN 45545 – From Standard to Challenges
Protecting staff and passengers from fires is the primary objective of EN 45545, which was introduced to standardize fire and smoke standards in rail vehicles across Europe. In subsection EN 45545-2, these standards also relate to the materials used for parts. A distinction is made between three hazard levels: HL 1, HL 2 and HL 3, which are based on the type of train and its operation. The materials used for the train equipment must meet the requirements of these risk categories as well as the further defined criteria of the product classes and their place of use. For example, seals and hoses must have different values in terms of flammability, smoke emissions and toxicity depending on the hazard level HL 1, 2 or 3 and their use inside or outside the train. Finding materials that meet these criteria is the crux of the matter for rail operators and manufacturers.
ÖBB faced precisely this challenge. For several years now, Austrian Federal Railways has been using 3D printing to carry out maintenance work, manufacture spare parts and produce small runs of parts ecologically. One specific example of this is the baby carriage safety retrofit ring, which ensures that baby carriages in the ÖBB double-decker pushchair train 8633 do not open doors unintentionally. This ring had to be manufactured in a small series and at the same time meet the EN 45545 fire protection standards. ÖBB brought TIGER Coatings on board for this task and the company was able to successfully complete the job thanks to its expertise and its classified, high-performance materials.
The retrofit ring was manufactured in small quantities from the flame-retardant material from TIGER Coatings. (photo credits: TIGER Coatings)
The Wels, Austria-based company TIGER Coatings draws on over 50 years of experience and expertise with polymers. TIGER Coatings is not only a 3D printing service provider, but also offers innovative materials for SLS 3D printing and CBAM printing systems under the name TIGITAL® 3D.
Its SLS materials include various series that open up specific high-performance fields of application thanks to their extraordinary properties. The HPP series (High Performance Polymers) is characterized by its rigidity and improved print quality. The Top Performance Polymer series (TPP) comprises UV-resistant and insulating materials, which are used in transportation and electronics, among others. However, the PPP series is particularly relevant for use on rails.
These premium performance polymers meet international and European standards in terms of fire protection. The flame-retardant materials are not only EN-45545 certified, but are also UL 94-V0 certified materials. In fact, it is the only material in the world that can meet this standard with a wall thickness of 2 mm for SLS-printed parts. It was precisely this material that was used to print baby carriage safety retrofit rings for Austrian trains.
TIGITAL® 3D Materials for SLS Printing
3D printing, in particular the SLS process, proved to be a suitable method due to its productivity, high reproducibility, precision and dimensional accuracy. Thanks to the existing standards, TIGER Coatings and its TIGITAL® 3D material already met one of ÖBB’s key criteria for this order.
However, anyone who has already taken a closer look at the SLS process is also aware of its high costs. SLS powder is very expensive, so it is an advantage if a large proportion of the non-sintered powder can be reused. The material portfolio of TIGER Coatings has a very high re-use rate of the residual powder, while at the same time retaining the properties achieved (flame retardancy, UV protection, etc.).
TIGER Coatings produced the spare parts on a Farsoon HT252P (photo credits: TIGER Coatings)
For printing, TIGER Coatings used the HT252P printer from Farsoon, a company with which it has a close working relationship. 110 parts were produced for ÖBB in this way and the necessary post-processing also took place in-house. Although the parts were printed in black, TIGER Coatings was able to use its background as a powder coating manufacturer to ensure that components could be coated with multifunctional coatings and that coatings in several colors were possible.
The manufactured retrofit rings are now being installed in ÖBB’s 8633 commuter double-decker reversible train and prevent the unintended opening of the doors by baby carriages. This component is a prime example of the use of the TIGITAL® 3D material, which is also suitable for similar components, including ventilation grilles, housings, handles and any spare parts. As a 3D printing material it is perfect for this application as the demand from rail operators for small quantities with complex geometries or individual dimensions is constantly increasing, while at the same time having to comply with existing standards.
However, rail vehicles are only one possible area of application for TIGITAL® 3D materials. In the future, TIGER Coatings wants to further improve its material portfolio through higher temperature stability and elasticity and thus open up new fields of application. You can find out more about the company and its plans HERE.
The manufactured part ensures that the buttons for opening the doors cannot accidentally be pushed by a baby carriage, which are attached next to doors in Austrian trains (photo credits: TIGER Coatings)
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*Cover Photo Credits: Double-decker push-pull train (DOSTO) at the platform, ÖBB – Harald Eisenberger