Attempting to combine TPU and PETG in a single 3D print can often lead to frustration when the materials fail to bond, separating as if they were never meant to be joined. This is a common challenge in multi-material 3D printing. Whether you're a beginner or an experienced maker, classic adhesion often reaches its limits when flexible materials like TPU meet rigid plastics such as PETG.

Why do TPU and PETG struggle to bond?

The reason lies in their distinct material properties. TPU is flexible and elastic, behaving quite differently during the printing process than PETG, which is stiff and dimensionally stable. Because of these differences, the two materials barely form a bond at the contact surface. When printing TPU and PETG together, weak transitions are often created that can fail under even slight stress. This is why many multi-material projects do not perform as expected.

The solution: Beam Interlocking

There is a solution that approaches the problem from a completely different angle. Instead of attempting to improve the chemical adhesion between TPU and PETG, Beam Interlocking relies on a mechanical principle. This means the materials are not "glued" together but are instead intentionally interlocked.

With Beam Interlocking, the slicer creates small, interlocking structures at the transitions between the materials. You can think of these as tiny anchors that penetrate one another. This results in a stable connection, even though TPU and PETG do not naturally bond well. This technique is highly effective for multi-material 3D printing because it bypasses the adhesion issue entirely.

In practice, this technique FINALLY allows you to create functional components where flexible and rigid zones are combined effectively!

Implementing Beam Interlocking in the slicer

For Beam Interlocking to function effectively, proper application within the slicer is essential. The transition areas between TPU and PETG must be sufficiently large to allow mechanical interlocking to form correctly. If the contact surfaces are too small, the connection may remain weak. Load-bearing capacity is also important; while the connection is stable, it relies on a clever form-fit rather than complete fusion of the materials.

Component planning is another frequently underestimated factor. By carefully considering where TPU and PETG meet and how these areas are structured from the outset, the full potential of Beam Interlocking can be realised. Instead of simply allowing two materials to meet, a targeted mechanical connection is established.

To ensure a secure connection, take the following points into account:

• Activate Beam Interlocking in the slicer.
• Plan transition areas carefully.
• Ensure sufficient contact surfaces.
• Avoid making connecting sections too thin.

Following these steps will ensure a high-quality result.

Conclusion: Making multi-material printing work

Ultimately, Beam Interlocking changes the approach to multi-material 3D printing. There is no longer a total reliance on materials adhering perfectly to one another. Instead, their specific properties are utilised and joined through intelligent structures. For 3D printing with TPU and PETG, this is the key to achieving functional, stable results.

Beam Interlocking is ideal for:

• Combining TPU and PETG.
• Joining flexible and rigid components.
• Printing functional multi-material parts.
• Creating mechanical connections.

Typical applications include:

• Grips with flexible sections.
• Damping elements.
• Functional prototypes.
• Components with soft-touch zones.