We're pushing the boundaries of FFF together with UltiMaker

"How strong are 3D printed parts?"

This is the question most engineers ask when considering 3D printing.

After all, it's extremely important to know what's possible with the tools at your disposal.

The engineers from Ultimaker, Covestro and the Royal Dutch Navy also got together to figure this out.

But not in the conventional way…

The traditional way to measure the strength of a material is by using a tensile testing machine. A small sample is printed and subjected to high force until it clicks. The force projected on the part divided by the surface of the central intersection at the time of fracture will express its strength.

While these numbers mean a lot to engineers, sometimes "seeing is believing." To really put an image in people's minds of just how tough 3D printed parts can be, Covestro, the Royal Netherlands Navy and Ultimaker have embarked on a unique collaboration to lift something seriously heavy.

But what will work? Weights for fitness? A motorcycle? A car? Maybe a big SUV? And then the Royal Dutch Navy asked:

„“““““““““ WHY NOT AN ARMORED CAR „“““““

You can watch the video here (Source: UltiMaker)

Creating the initial design

To lift a heavy vehicle using a 3D printed part, we first had to analyze the hardware we could use.

The Royal Dutch Navy had a special lifting tank that used two opening steel rings to connect to their crane and to the ropes attached to the vehicle to be lifted. An extended O-link could connect these two metal rings and lift the heavy vehicle.

The 3D printed link had to interact perfectly with these opening rings (Photo: UltiMaker)

After importing the geometry of the steel rings into the CAD software, Ultimaker application engineer Lars de Jongh was able to create the initial design for the connection. Lars first defined the design requirements:

  • The link had to have a flat side for stable 3D printing
  • The connection had to be printed with the layer lines in the same direction as the forces projected onto the part
  • The interacting surface of the printed part and the metal rings should be as large as possible to distribute the forces evenly
Their exact geometry was imported into CAD to inform the design of the part. (Photo: UltiMaker)

Finding the right material

The Ultimaker Marketplace is packed with hundreds of materials. Each of them has a unique combination of properties, making it highly likely that your part will meet the requirements. The material required for this test had to be extremely strong, but it also had to be able to absorb short peak forces. Addigy® F1030 CF10 from Covestro meets the requirements. This nylon-based polymer is loaded with carbon fiber and can be printed using the Ultimaker S5 and CC print core.

Design optimization through simulations

Covestro simulates the effect of forces on their material to optimize the design (Photo: UltiMaker)

It takes less time to 3D print a solid 2-kilogram link than to produce it using traditional methods. However, the number of iterations required to validate the correct geometry means that time is still a factor. Therefore, the design was optimized before printing using computer simulations.

This saved time as fewer iterations were needed to create the final part (Photo: UltiMaker)

Covestro digitally applies the forces to the design using software that knows the exact physical properties of their carbon fiber nylon material. By running simulations, we were able to determine where the design needed to be adjusted and where material could be removed. This created an optimized design that could lift more weight while requiring less material, resulting in faster production times with less cost.

Checking the simulation

Before we could lift our heavy vehicle, we had to physically verify the calculated strength of the printed part. Two designs were generated for two sizes. The first was a 1 kilo link which we believe can support 12 tonnes. The second, weighing approximately 2 kilograms, is believed to be able to support 38 tons. The Royal Netherlands Navy has an industrial tensile tester in place that can project up to 343 kilonewtons of force onto an object. Both the initial and optimized versions were tested.

The Royal Dutch Navy tested the 2-kilogram link to withstand 38 tons under perfect conditions (Photo: UltiMaker)

The optimized design was able to withstand higher force while weighing a third less. The difference between the tested results and the simulated numbers was also extremely close, with only an 1% reduction on average. This made this workflow accurate and profitable in time to market and increased productivity.

Lifting two vehicles

After a few months of designing, printing, testing and planning - it's time for action! Two links would lift a real military heavy machine. At a Dutch army base in the south of the Netherlands, the 13th Light Rhino Brigade helped us with their armored vehicle. Their Leopard 2 'Buffalo' has a front-mounted crane and is designed to extract heavy vehicles such as trucks and battle tanks.
For a warm-up, the 1-kilogram link was used to lift a military version of a Mercedes jeep weighing more than 2 tons. This was no problem at all: the vehicle lifted easily. Then it was time for something bigger.

The 1kg version of the 3D printed link was used to lift a military jeep as a warm-up (Photo: UltiMaker)

The 2-pound rigid carbon-fiber-reinforced nylon link was placed between the M113 armored vehicle and the Buffalo crane. The metal rings were tightened in place and four ropes were attached from the lower hook to the vehicle. The crane slowly began to move upwards, putting the ropes and the 3D printed part under tension. The 12-ton vehicle then slowly rose up, hovering above the ground, hanging on a 3D printed link! Buffalo drove around, backwards, forwards, reversed directions, but the connection held up perfectly. The cooperation gave a very successful result.

Lessons and key takeaways

The project was successful not only because of the working relationship. We also learned a lot along the way.

It was amazing to see that CAD simulations have come a long way, not only simulating shape, but giving accurate predictions taking into account material and even fiber direction. Being able to rely on such tools is a great benefit to engineers.

Although all parts were printed in properly maintained facilities and the materials were not exposed to moisture, there was still a noticeable difference between the versions printed in a dry warehouse and the parts printed with intentionally dried spools of filament in a heated, dry print room. Nylon absorbs moisture and this can lead to weaker prints. That is why it is very important to know the properties of materials and handle them accordingly.

Eye to see hand to touch

The technical data sheet will tell you the strength of the material in abstract numbers. But when you see what can be achieved with robust and optimized 3D printed parts, it's easier to understand the possibilities of additive technology and get inspired for new and exciting applications.


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