DB ESG, in collaboration with Angel Trains, were the first in the UK to produce 3D printed replacement parts and put them into commercial service on a passenger train. Our first project in 2018 was focused on seven grab handles and four armrests. For both of these parts, the cost to additively manufacture was comparable to the original manufacturing processes. However, the real advantage was a substantial reduction in lead time; the armrests were produced within 3 days, in comparison the original part lead time of 4 months. They were also able to be produced at a much lower minimum order quantity, as low as a single unit.
These parts were finished to such a standard that they were indifferentiable from the original components. The parts were fitted to a Class 165 train owned by Angel Trains and operated by Chiltern Railways in the summer of 2019. A visual inspection of the parts was conducted two years later, and the parts remain in operation to this date.
Since the introduction of the first additively manufactured part into the rail industry, we have rapidly expanded into the supply of additively manufactured parts for the purposes of prototyping, tooling, and final part manufacture. We now have several suppliers that provided a wide range of additive manufacturing technologies such as:
We also offer a wide variety of post processing options, including chemical and vibration smoothing to create smooth finishings in the natural colour, dyeing or painting, and electroplating. We have even produced parts with impact resistant coatings, to fit on the outside of vehicles and protect against ballast strikes. These post processed final parts can be indistinguishable from the original ones.
The project aim was to investigate the benefit of using additive manufacture (AM) to produce more complex assemblies, for this example, a Class 165 Power Brake Controller (PBC) cover.
The traditional cover was composed of:
It isn’t just the replacement of parts and components. The PCRB Installation Jig is a typical example of using 3D printing to increase the efficiency or repeatability of installations and maintenance procedures. This jig was created for exactly that – an installation that required tight tolerances in a confined area.
The purpose of this project was to provide the customer with an efficient, consistent and repeatable way to install the equipment.
Chiltern Railways’ Class 165s are fitted with cast aluminium grab handles, however the original manufacturer of these has ceased trading. The original engineering drawings are unavailable, and the last remaining spares have already been utilised.
A replacement handle therefore needed to be provided, ideally one that matched the existing part to avoid a wholesale change-out of grab handles.
Sourcing replacement parts that are manufactured via traditional methods, such as casting or injection moulding, for rail vehicles is prohibitive. These methods require large upfront investments in tooling and moulds, which if only a small number of parts are required, can significantly increase the cost. Using digital manufacturing mitigated these issues.
Seven grab handles have completed an in-service trial and will remain fitted for the duration of their component life with Chiltern Railways. The full cost of the 3D printed replacements, including design and prototyping was 78% cheaper than the cost of producing via the conventional method. This digital workflow also reduced lead times from 4-5 months to just a few days for production.
We are focused entirely upon problem solving. Whether the problem is obsolescence, long lead times, large minimum order quantities or price-rises. Our solutions are not merely centered around replacing parts and components, we can create bespoke items entirely from scratch; we have 3D printed new enclosures for test boxes and new wiring glands for engine bays with heat and chemical resistant rubber. Phones, paneling, cab-desks and impact-resistant exterior parts such as brake-box covers. Additive manufacturing allows for ultimate flexibility. This ultimate flexibility allows us to address the specific reason for your enquiry resulting in targeted problem solving.
We also use Additive Manufacturing to produce quick prototypes that can be sent to the end customer prior to production ordering. These prototypes can be produced by one of our suppliers or in- house using DB ESG’s 3D printer. Additively manufactured prototypes allow for iterative design changes to be carried out to meet the specific application requirements; ensuring that you’ve ordered a part you can rely on.
We were the first to put a 3D printed part on a rail vehicle in the UK and have gone from strength to strength in the 5 years since. The rail industry is quickly learning the huge benefits this technology can bring, particularly within obsolescence. We are very aware that the only way we can stay as the rail sector market leader in this area is by continued investment in research in development. We are continually investigating new methods and processes to deliver a wider number of solutions, provide even quicker response times and deliver even greater cost efficiency.
A key part of this is investigating new and different materials. Our initial projects were generally focused around using filament based thermoplastic materials such as Ultem™ 9085, Markforged Onyx FR and PETG which we used widely now for numerous applications,.
We have since 3D printed powder based Nylon materials such as PA12, PA11 and PA2200 which allows for complete design freedom due to not requiring support material. The latest 3D printing materials that we are researching and actively applying to new applications are various grades of metal in both powdered and wire from as well as, most recently 3D printing elastomers.
When we are first introduced to a new project one of the first considerations we make is regarding fire compliance. This is because any part that is to be installed on rail vehicles must be compliant with BS EN 45545 which can define what materials and, as a result, what manufacturing processes we can use. To determine what fire compliant materials we are able to use, we take the overall mass of the original part and where it is installed on the desired vehicle (either interior or exterior) and review this against BS EN 45545 to understand which requirement set it falls under.
Once we have defined which requirement set needs to be met, we then choose the suitable materials for the application. For example, if requirement set R1 is required (most strict level of fire compliance) we have a 3D printing material named Ultem™ 9085 as well as various metal alloys that would all be compliant. This would allow for many available manufacturing processes ranging from 3D printing to CNC machining and other alternative manufacturing processes to be used to produce a complaint part.
If the customer is required to process an engineering change to install re-engineered parts from DB ESG, we are also able to provide a technical report/letter to provide evidence on how the chosen material and manufacturing process for the part is compliant to BS EN 45545. As well as this information material datasheets can also be provided to the customer to validate the fire compliance of the chosen material.
If we have a part for a project that undergoes loading conditions whilst in service, we can carry out finite element analysis (FEA) to simulate a multitude of loading and boundary conditions. All FEA carried out by DB ESG is to railway standards GM/RT2100 ‘Requirements for Railway Vehicle Structures’ and BS EN 12663-1 ‘Structural Requirements for Railway Vehicle Bodies. Part 1 – Locomotives & Passenger Rolling Stock’. If required a structural analysis report can be provided to the customer to act as evidence if an engineering change is required for the installation of the re-engineered part(s).
Although the preconception is that only traditional manufacturing processes and materials such as metal allow welded fabrications can be structurally analysed using FEA, DB ESG have undertaken a significant amount of research and development into the FEA of 3D printed parts. Using the material properties provided by the 3D printing material manufacturers and correctly modelling the parts in the FEA software to simulate variable densities, an accurate representation of the in-service performance of a part can be achieved. This also includes 3D printed parts where a reinforcing glass or carbon fibre layer has been introduced to improve strength/stiffness.
However, the major limitation to 3D printing materials is the lack of fatigue properties available This means that when a part is required to undergo fatigue/cyclic loading whilst in service a 3D printing material is not always suitable. However, if this is the case we are still able to resolve your obsolescence issue. Instead, a metal alloy material with known fatigue properties would be selected. This would then allow DB ESG to undertake fatigue loading FEA analysis and provide this information to the customer for validation.