How To Strengthen 3D Printed Parts

  • The random act of “throwing fibres into the mix” to strengthen a part has been an expensive failure.
  • Additive Manufacturing has to all intents and purposes been accepted by the industry. Creating a 3D printed part is now relatively straightforward but strength and durability are still major hurdles.
  • Manual and automated fibre routing is an option for selective parts but is not yet scalable to an industry level.
  • Heat treatment, fibre supports and detailed layering in the 3D printing process would seem to be the way forward. Progress has been made in this area but more research and development is required.

Additive Manufacturing is gradually gaining inertia throughout the different branches of industry. However, one of the mains obstacles is the endurance and performance the parts deliver – the need to strengthen 3D printed parts is paramount. Since the most commonly used material in 3D printers is a form of polymer or plastic, the limitations in the type of parts that can be manufactured through the process, and their durability, are there for all to see. Thankfully, there have been a number of recent developments and future possibilities when it comes to manufacturing stronger parts – able to rival and compete with steel and composite ones. The ability to strengthen 3D printed parts would add a whole new layer of value to the 3D printing process.

New processes in Additive Manufacturing:

The first efforts to strengthen 3D printed parts were focused on simply using high strength material, and therefore adapting the 3D printers to the requirements of such deposition. SLS (there are other processes as well) is one method used in additive manufacturing to provide high strength parts and build components with very solicited working conditions. These processes are commercially available throughout different companies and are known as SLM (Selective Laser Melting), EBM (Electron Beam Melting) and DMLS (Direct Metal Laser Sintering). They rely on a powder deposition method to spread powder layers and construct layers that are either bound or melted together.

These processes are however very expensive and demanding in terms of resources and energy consumption. Moreover, their use is still restricted to a few components given the complexity of inspecting the parts and the expensive if not unavailable analysis protocols for them (required for certification and testing purposes).

Fibre reinforcing:

Since the composites’ surge, “everything is better with a handful of fibres thrown in” became a trend for some time. Therefore, throwing in short carbon fibres in the resin of the 3D printer was an understandable development. After all, the resin will act as a matrix and the fibres will provide the mechanical properties desired in a strong part. Needless to say, many learned to their expenses that no, throwing a handful of long, and even worse, short carbon/glass fibres in the cauldron won’t make your parts better. If anything, they can prove disastrous due to the negligence of the anisotropy of these components and the unawareness of the amount of calculations and study they require before including them in a composite and structuring them in a specific use. Research into the micromechanics of the layers and the fluid dynamics of the reinforced resin is ongoing to check the predictability of the fibres’ orientation and their properties within the FDM process.

Fibre routing:

There is a more informed way to include fibres in a 3D printed part: either through some brands of 3D printers that allow the user to choose the fibre routing and hence orientation while building the layers, or through manual composition by filling a 3D printed shell of the desired part. Both of these methods are used extensively by hobbyists. While these methods can give satisfactory results, they require extensive post-treatment, and aren’t used on large scale parts, let alone ones for industrial purposes.

Adaption of parts:

On occasion a complete revision of the parts’ model will be required when it is submitted to a slicer. From reconsidering the shapes to scaling the geometry and modifying certain features, there are several tricks to 3D printing.  To ensure a part is strong on its own, it will either be assembled using supports, or treated with heat and a special coating. These processes are the most common currently used and imply there is still work required to encourage widespread use of AM.

Even though research is ongoing through the viscoelastic aspect of mould flow, short fibre orientation and the degree of control we can have on it, there have been some promising results. Very soon we may be able to automatize the whole process and come to a situation where dumping a handful of short carbon fibres in the machine will result in adequate orientation within a 3D printed part. While there is much work still to do there is no doubt that the process required to strengthen 3D printed parts is moving in the right direction.

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3 thoughts on “How To Strengthen 3D Printed Parts”

  1. Some 3D printers have the ability to make parts of any type of material you want.such as J750 Stratasys with PolyJet technology.

    Each layer can have its own material and with GrabCAD Voxel take on a unique color.

  2. Reinforcement: Why not try glass flake instead of glass fibre. Glassflake has been shown to substantially improve modulus, reduce creep in compression, improve tensile strength along with tribological properties in thermoplastics.
    It is necessary to experiment with flake thickness and particle size of the flake, loading level and also chose the correct silane treatment to give good bonding to the thermoplastic. Addition by weight can be anything from as little as 4% to as high as 40% dependent upon the type of plastic and requirements. One down side is impact resistance is sometimes reduced in materials that would otherwise have exceptional impact resistance but it depends on what properties you are after. Silanes used can be on the flake itself (preferable) or added to the powder. Usually these are amino, vinyl or epoxy silanes but there are many can be used. HDT and fire resistance can also be significantly improved….take a look at it!

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