Napoli buses rely on 3D printing

The Italian engineering company 3DnA uses 3D printing to help service public transport buses, including making replacement parts for the trolleybuses in the city of Napoli.

Napoli’s trolleybus fleet is dependent upon the overhead power supply lines.

The trolleybuses, along with the entire public transportation network in Napoli, are run by Azienda Napoletana Mobilità, or ANM. But the company found that many of the trolley heads for these buses were broken or had simply reached the end of their service life. The trolley head is a critical part that connects each trolleybus to the overhead power supply line, so the buses can’t function without it. However, neither the trolley buses nor the parts for them are still being manufactured so it’s difficult to find replacements, which would eventually have left the fleet inoperable.

Faced with this difficulty, ANM turned to 3DnA, which printed new parts using its Stratasys F900 3D printer. Alessandro Manzo, 3DnA’s General Director, says: “Creating the trolley heads with traditional manufacturing processes would have taken up to 12 months, resulting in a lengthy downtime for the vehicle that is simply not an option.”

Instead 3DnA re-engineered the part using 3D scanning. Importantly, by leveraging the geometric freedom enabled by additive manufacturing, the team was able to re-design the part so that in the event of damage, only a small component of the trolley head would need replacing – not the entire part, as previously.

Manzo explained: “Using our F900, we were able to produce and deliver about 20 of the most critical parts of the trolley head in two weeks, enabling ANM to eliminate further risk of downtime to its fleet and ensure reliable transportation for the three million citizens of Naples. Overall, having this level of production flexibility is extremely important to ANM, as it can now order parts based on actual needs as opposed to warehousing large quantities of costly inventory.”

This image shows the 3D-printed upper casing of the trolley head 3D, using Ultem 9085 resin on a Stratasys F900.

The new trolley head comprises a core metal structure, with the F900 used to produce the exterior casing that connects the trolley head to the overhead wires. Such has been the impact that it has now become the part of choice for the whole fleet.

For the exterior casing, 3DnA used Ultem 9085 resin, which is tough enough for everyday use and meets the necessary electrical insulation standards. Manzo notes: “The part cannot conduct electricity, so having this material is essential. In addition, Ultem 9085 resin provides us three key criteria required for end-use transportation applications: excellent heat resistance with a heat deflection temperature of 153°C, it is a flame-retardant thermoplastic, and offers a very high strength-to-weight ratio.”

Manzo adds: “Without the ability to produce parts with such a high-level of accuracy this would not have been possible. That is where the beauty of the F900 comes in – not only do you get supreme part accuracy, but it’s backed up by a level of repeatability unrivalled in the industry.”

He concludes: “We believe additive manufacturing will become the prominent spare part production method for the transportation sector. With low volume, on-demand production made cost-effective, the industry is ripe for transformation. Cases like ANM exemplify this, and as a result of this project, we’re already in advanced discussions with several transportation management companies across Italy to support their spare part requirements with this technology.”

You can find further details on this approach from, on the F900 and Ultem 9085 from, and on the trolleybuses from

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