Modern FDM printing in engineering: From prototypes to durable functional parts
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FDM/FFF 3D printing has undergone a significant leap in professionalization in recent years – and noticeably in recent months as well: What used to often look like "visibly layered" PLA/ABS prototypes is now, in many cases, an industrially produced functional part. Surface finish, dimensional accuracy, process stability (drying, temperature control, sensors), and above all, the range of available materials have improved so dramatically that FDM components have become a genuine alternative to milled or cast parts for numerous applications.
A key point: Classic FDM anisotropy can now be significantly reduced. Improved temperature control (housing/chamber), optimized polymers, fiber fillers, process profiles, and post-processing (e.g., annealing) are bringing the properties between the axes closer together – many components behave "quasi-isotropically" in practical applications, even though the build direction (especially the Z-axis) remains a crucial design parameter. Studies on Onyx, for example, show significant effects depending on the orientation/positioning, while the deviation within the platform orientation angles can sometimes be relatively small.
Material reality: “Engineering filaments” instead of craft plastic
The biggest lever for "professional" today is not just the machine – but the material system:
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CF-reinforced copolymers (PETG-CF) provide good surface finishes, low shrinkage, improved stiffness, and robust process windows.
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CF-reinforced polyamides (PA12-CF, PA6-CF) deliver what was previously hardly expected of FDM: high strength/stiffness, usable temperature resistance and functional components in the direction of "lightweight metal replacement" (with suitable geometry design and load case).
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Special PLA variants such as "Aero/Lightweight-PLA" utilize foaming effects for low component density (e.g. UAV/model making), but are still thermally limited, as is typical for PLA.
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Composite base materials such as Onyx (nylon-based, micro-CF-filled) are an established “workshop currency” for many fixtures/tools – with strong heat resistance compared to standard thermoplastics.
| material | UV stability (trend) | Strength (tensile strength, MPa · Best-case) | Stiffness (Young's modulus, GPa · Best-case) | Density (g/cm³) | Moisture absorption (% m/m) | Temperature stability (HDT @0.45 MPa, °C) |
|---|---|---|---|---|---|---|
| PETG-CF | medium-good (possibly UV-stabilized) | ≈ 51 | ≈ 3.38 | ≈ 1.26 | ≈ 0.30 | ≈ 81 |
| PA12-CF | medium (highly dependent on additives) | ≈ 77 | ≈ 3.31 | ≈ 1.06 | ≈ 1.5 (Equilibrium) | ≈ 131 |
| PA6-CF | rather low to medium (additives/coating recommended) | ≈ 105 | ≈ 7.45 | ≈ 1.17 | ≈ 3.33 (Equilibrium) | ≈ 215 |
| Aero-PLA (foaming) | medium (PLA: UV often ok, heat limiting) | ≈ 26 | ≈ 1.67 | 1.21 (filament) Component: significantly reduced due to foaming |
≈ 0.48 | ≈ 54 |
| onyx | medium (nylon-based; for external use, usually protect) | ≈ 40 (Yield) | ≈ 2.4 | ≈ 1.2 (nominal) | ≈ 2–3 | ≈ 145 |
Note: These are manufacturer-neutral, practical upper limits (best-case scenario). Actual values depend heavily on the print profile, component geometry, orientation (XY vs. Z), drying, and any annealing.
Outlook: Special applications that are "easy" today
1) Flexible components with TPU (seals, protection, gripper pads, cable protection)
TPU has now become commonplace – from protective caps to functional sealing/damping elements. Typical Shore hardness ranges in the FDM environment are often between 85A and 95A.
2) Tribofilaments for plain bearings & wear parts (e.g. igus iglidur®)
One of the most exciting developments is tribofilaments (with solid lubricant systems), which enable FDM-printed plain bearings, guides, or wear-prone parts. igus describes, among other things, very high abrasion resistance and low coefficients of friction for its iglidur tribofilaments.
Conclusion
Modern FDM 3D printing is now an engineering tool, no longer just a prototyping gimmick. CF-reinforced polyamides deliver strengths and stiffnesses that, in suitable applications, come remarkably close to those of "classic" lightweight metal solutions – with the added benefits of design freedom and rapid iteration. At the same time, TPU and tribofilaments enable entirely new classes of components (flexible, sliding, wear-optimized) that would often be significantly more complex to produce using conventional manufacturing processes.
