Faced with the challenge of producing replacement parts for a diverse fleet of trains, UK firm Angel Trains found a powerful cost-effective solution in 3D printing.

Founded in 1994, Angel Trains is a leading rolling stock provider for the UK rail industry, financing and delivering high-quality trains to UK passenger service operators. Each year, it makes significant investment in innovative solutions to modernise train fleets. One of its biggest challenges is finding an alternative to the traditional supply chain for replacement parts, which struggles to cope with growing demands.

Unlike the automotive industry, where vehicles are mass produced in millions each year, rail industry fleets are comparatively small, and in some cases more than 30 years old. This combination presents several challenges for train operators, especially regarding vehicle maintenance and part replacement.

“In recent times, we’ve seen growing concern among operators that sourcing replacement parts for older train fleets at a reasonable cost and in a short timeframe is proving increasingly difficult,” explained James Brown, Data & Performance Engineer at Angel Trains. “The problem is that traditional manufacturing methods only make it cost-effective to produce high volumes of spare parts, even though an operator may only need a few obsolete train parts replaced. Lead times can also take months, exacerbating the issue even further.”

As a result, Angel Trains teamed up with Stratasys and engineering consultancy DB ESG to show train operators how they can overcome these hurdles by 3D printing lower quantities of parts in a fraction of the time and cost of traditional methods. This cross-industry collaboration soon resulted in the first 3D-printed parts ever deployed within an in-service passenger train in the UK. They included four passenger armrests and seven grab handles, installed on Chiltern Railways trains.

Cutting production costs and lead times

Stratasys’ Rail Industry Solution comprises rail-qualified materials and production-grade fused deposition modelling (FDM) 3D printing. This lets Angel Trains achieve major time and cost efficiencies in part replacement.

Using conventional manufacturing, the lead time for the armrest would be approximately four months. However, according to Brown, the final part can be produced within one week with Stratasys, representing a lead-time decrease of almost 94%, with cost savings of up to 50% per part.

Similarly, in the case of the on-seat grab handle, the replacement part was obsolete, and the original supplier was no longer in operation. To make new grab handles, a new manufacturing tool would have been required, costing up to £15,000 ($27,500) with an expected lead time of two-and-a-half months. With the Rail Industry Solution, the grab handles were produced in just three weeks at a significantly lower cost per part.

“With Stratasys’ Rail Industry Solution, train operators can be much more responsive to replacing passenger-facing parts that get damaged or vandalised,” said Brown. “An obsolete replacement part can be 3D printed on demand and installed immediately, enabling operators to get vehicles back into service quicker and better maintain their trains – improving the quality of service for passengers.”

To overcome the challenge of certifying 3D printed parts for use in passenger trains, DB ESG conducted comprehensive testing on a range of industrial-grade 3D printing materials. The final parts were printed in ULTEM 9085 resin using a Stratasys Fortus 450mc 3D printer. The highly accurate production printer features a large heated build chamber, so parts meet the strict tolerances and repeatability requirements of industry, as well as allowing large single parts or multiple smaller parts to be printed in one run. Last year, ULTEM 9085 resin was certified to the rail industry’s fire, smoke and toxicity standard, EN45545-2, a first for the rail industry.

Martin Stevens, Mechanical Engineering Manager at DB ESG, commented: “Gaining this certification removes a major barrier that has prevented more widespread implementation of 3D printing across UK trains.”

Improving passenger experience

With low-volume production now achievable, Angel Trains is already exploring how it can leverage Stratasys’ Rail Industry Solution to customise interiors better suited to the passenger commute.

“We’ve tested 3D-printed seat-back tables with braille, informing the passenger that the toilet is ten rows back from that particular seat,” said Brown. “This level of customisation is unprecedented and can only be enabled by 3D printing, offering the potential to significantly improve passenger experience in the future.”

Following the success of the Chiltern Railways trial, the group has established a repeatable process for future projects that produces parts compliant with rail industry standards and suitable for use in passenger vehicles. With positive responses from train operators, the deployment of 3D printed parts will now be extended onto trains with another UK passenger train operator.