Additive manufacturing: when 2 become 1

Additive manufacturing has become an integral part of most development departments, production lines and workshops. While the technology was primarily used for prototypes due to the material development, this has evolved over the years.

Engineering plastics companies have been developing and producing 3D printing materials for years but igus® has taken this one step further in recent times. The development of functional high-performance polymers has always been at the forefront of everything igus® does.  Developing additive manufacturing a few years ago allowed igus® to include filament printers (FDM) and laser sinter printers (SLS).

This article highlights materials for moving applications in which friction and wear occur in contrast to static components.

Multi-material 3D printing

When discussing “multi-material components”, we are referring to 2-component parts. This introduces the possibility of manufacturing a product from two different materials in one production step, i.e. without subsequent joining. While on the one hand, designers are considering how additive manufacturing can be used as a replacement or supplement to existing manufacturing techniques, manufacturing technology is a bit ahead of product development so, trying to establish the profitability and suitability of using this technique is also open for consideration.

Processes that manufacture components from the liquid or powdered raw material have not offered this option for procedural reasons: it is reserved for 3D printers that use the strand deposition process (FDM/FFF). This is due to the method: the raw material – filament – is applied through a melting nozzle, of which almost any number can be arranged on one or more print heads. The second nozzle on the print head is usually used for processing support material that does not remain on the component after printing. However, different filaments can also be combined into one component in this way.

Since the 3D printer alternates between the two materials in each layer, there is no geometrical limitation as to how the two “phases” can be combined. The materials can be intertwined, used in an encompassing manner, alternating layers, etc. Depending on the 3D printing software, different features can be assigned to one or the other material, so that you can be very creative when combining the materials.

Different materials and filament variety

In order to recognise the potential of this manufacturing option, you need to consider the variety of materials that 3D printing with filament offers. Here is an overview of the different filament types and the functional properties of each type of filament:

  • Optics: filament in various colours, we can match RAL tones and different surface textures such as: glossy, matt, translucent and metal-filled
  • Mechanical properties: tough, temperature-resistant, fibre-reinforced, flexible
  • Special properties: fire retardant, anti-static or conductive, tribologically optimised and foaming

As already described, two filaments can theoretically be combined in any way on a commercially available printer. The only limiting factor is the significantly different processing temperatures. The materials do not necessarily have to fuse with each other at the interfaces. This is due to a structural fuse fit of the two materials, which can achieve an inseparable connection between the two phases as well.

Requirements for the combination of different materials

As established, two different filaments can be connected to each other in different ways to form a durable component. The materials in the interfaces fuse or “weld” in a manner similar to that between two layers of the same material. The more similar the filaments are in terms of the polymer compositions the better the fit, and the processing temperatures tend to be similar. Despite this, dissimilar materials can also have a structural bond. Limits are only set here if the processing temperature of one material exceeds that of the other to such an extent that the second material can no longer be processed in a dimensionally stable manner.

A form-fitting design of both phases can be used to create a connection that cannot be broken without being destroyed. There are different approaches to this, which are explained in more detail in the following section.

Construction for multi-material 3D printing implementation in the CAD system

If you want to start 3D printing of multi-material components, you need to establish how to teach the 3D printer where to use which material. Using the software and hardware used at igus®, it should be shown as an example how to proceed. Autodesk Inventor is used for the construction. As a 3D printer with two material nozzles, an Ultimaker of the newest generation, as well as the matching slicer software Cura, in the current version.

If you would like to explore the idea of a multi-material part that has all of the low wear benefits of our i150 print filament but has the housing strength of carbon fibre, get in touch. We can help with this and have been successful in supplying parts in this fashion.

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