UltiMaker Feature Highlight: Dual Extrusion & Material Interlocking

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Bennie Sham

December 30, 2024

In today’s fast-paced industrial landscape, innovation in 3D printing technology is driving efficiency and aims to transform key sectors such as manufacturing, packaging, defense, and medical industries. In this article, we aim to highlight the synergy between dual extrusion and material interlocking and showcase how UltiMaker’s 3D printers are redefining industry standards.

Dual Extrusion

Single extrusion was the initial standard in 3D printing, using one nozzle to print a single material per item. While sufficient for basic designs, it limits part complexity and requires additional steps such as manual support removal or assembly of multi-material parts.

The most common way of circumventing this limitation is through the use of automated filament handling technology that switches the filament type being fed into the extruder. However, this comes with its own inherent limitations, as these systems take time to switch between the different materials being fed and waste filament as part of the changing process.

This is where dual extrusion came in. Dual extrusion, which uses two independent nozzles to deposit filament within the same print, introduced the capability to print with multiple materials in one operation, allowing for greater versatility and complexity in the designs.

Applications include the ability to print assembly-free products such as parts with built-in hinges or snaps for immediate use, wearable parts that combine soft and hard materials (e.g. a soft gasket locked into a rigid frame), color-coded parts, and complex geometries through the use of soluble supports.

Let’s explore some of the key benefits and examples:

Multi-Material Printing for Functional Parts

The combination of different materials such as rigid and flexible or functional and structural has already seen success in the medical field as it allowed researchers at the University of Central Lancashire to develop a prototype exoskeleton using a combination of PLA for the internal core and Nylon and TPU for the external shell. This resulted in components that would conform to a person but also provide rigidity due to the soft exterior and hardened interior.

Another great example that we recently referenced in our Applications of 3D Printing in Manufacturing article showed how Volkswagen Autoeuropa developed liftage badge jigs using TPU for the surface in contact with the car in order to not scratch the paint and a hard structural filament for the frame.

Rendered liftage badge

3D printed liftage badge

Soluble Support Structures for Complex Geometries

A popular option for dual extrusion 3D printing, the use of soluble supports that dissolve in water allow for exceptional design freedom without adversely affecting the surface quality of the print. This si especially useful when printing moving assemblies or precision end-use parts.

A print with PVA supports submerged in water

After submerging in water, PVA material will dissolve

Optimization Through Multi-Material Combinations

We’ve covered a plethora of examples in our Applications of 3D Printing in Automated Packaging article where dual extrusion has been employed to create a wide variety of parts that were cheaper to produce when compared to traditionally sourced alternatives without compromising on functionality or part integrity. A common part in packaging lines, infeed starwheels, can be made out of a stiff high resistant material with a low friction outer wall.

Material Interlocking

A critical component for the majority of applications that benefit from dual extrusion is the ability to design parts or structures that lock together physically, either during or after the printing process. This enhances their mechanical and functional properties or allows assembly without adhesives or fasteners. It is important to understand the following concepts of material interlocking:

  • Geometric Interlocking: refers to the use of features like dovetails, snap-fits, or undercuts that physically restrict movement.
  • Multi-Material Interlocking: refers to the properties of two or more materials to be simultaneously printed together(e.g. rigid and flexible) to create functional or decorative connections.

We will focus on the latter as in the context of 3D printing this is usually achieved at the design phase through the inclusion of interlocking geometries between the different materials. While this is a viable and often employed method, it is also time-consuming and requires a high level of design engineering knowledge and a certain degree of familiarity with material compatibility, hindering its accessibility.

This is no longer an issue since we’ve included material interlocking as a feature in our Cura slicing software. Since version 5.3 Cura users have been able to use the “Generate Interlocking Structure” setting for any part designed for multiple material printing to automatically generate an overlapping pattern that physically “locks” the two materials together.

With applications constantly being explored, this feature allows for the design of parts without the need to consult a material compatibility chart, further expanding on the potential material combinations that would otherwise be chemically or thermally incompatible.

A great example on how this feature was leveraged is the Heineken can pusher which is a part that is used in the production line to push a series of 8 pack beverage cans from one conveyor to another three separate conveyors.

They needed to redesign the original part which caused issues as it pushed the 8 packs from the apex of the cans which sometimes resulted in the cans tipping over causing a stop in the production line. The new 3D printed part was designed to have a larger surface area and using the material interlocking feature they were able to print the inside of the part with a red PLA for the structure and the outer layer with a wear resistant material like Nylon.

3D render visualizing the Heinken can pusher

Interlocking geometries of Heinekens can pusher

The added benefit of using different colors for the materials was that it was a lot easier to know when the part needed to be replaced as when the outer layer wore down the internal red PLA material became more visible acting as a wear indicator.

Leveraging Dual Extrusion & Material Interlocking

The future of design and manufacturing lies in technologies that push boundaries and redefine possibilities. With dual extrusion and material interlocking, the UltiMaker Factor 4 empowers professionals across industries to create complex, high-performance parts that were once thought impossible. From multi-material prototypes to durable, assembly-free products, this cutting-edge 3D printer combines precision, versatility, and ease of use to meet the demands of modern manufacturing.

Contact UltiMaker and discover how the UltiMaker Factor 4 can revolutionize your workflow and transform your ideas into reality.

Learn more about Factor 4

The Factor 4 industrial-grade 3D printer streamlines production, simplifies processes, and keeps operations running.

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