FDM 3D printing builds parts from engineering-grade filament, one layer at a time, and we can vapour polish every FDM material we offer to take parts from good to great. Incremental-AM runs FDM alongside our HP Multi Jet Fusion systems. We use it where it is the better fit: specific engineering materials such as ASA and carbon fibre composites, larger chunky parts, and quick jigs and fixtures.
Vapour polished FDM: from good to great
Layer lines are the giveaway of an FDM part. Our vapour polishing smooths them away and seals the surface, so an FDM part looks and feels much closer to a moulded one. All of our FDM materials can be vapour polished, including the carbon fibre composites. Few FDM suppliers can offer this.
- Smoother surface: layer lines are softened, giving a more even, semi-gloss finish.
- Sealed: a closed surface that is easier to clean and less likely to trap dirt or moisture.
- Better looking: customer-facing parts, covers and housings that look finished, not printed.
Just choose vapour polishing when you ask for a quote. See also TN-005: Design tips for vapour polishing.
FDM materials
| Material | Best for |
|---|---|
| PETG | Tough, durable and good value, with good chemical and moisture resistance. A dependable choice for everyday functional parts and enclosures. |
| ASA | UV and weather resistant, so it is our choice for outdoor parts, housings and covers. |
| Carbon fibre nylon (PAHT-CF) | High-temperature nylon reinforced with carbon fibre: stiff, strong, tough and wear resistant, and the strongest of our composites between layers. Ideal for jigs, fixtures, brackets, clips and end-of-arm tooling. |
| Carbon fibre PET (PET-CF) | Very stiff and dimensionally stable, absorbs very little moisture and has good chemical resistance. A great all-round composite for fixtures and brackets. |
| Carbon fibre PPA (PPA-CF) | Our highest-performance filament: exceptionally stiff and strong, with heat resistance above 200 °C for demanding industrial parts. |
Need a different filament? Ask us. If we don't stock it, we'll suggest an alternative.
FDM material properties
Typical values from the filament manufacturer's datasheets. XY is along the printed layers; Z is across them.
| Material | Tensile strength XY | Tensile strength Z | Flexural strength XY | Notched impact XY | HDT @ 0.45 MPa | Density |
|---|---|---|---|---|---|---|
| PETG | 48 MPa | 39 MPa | 81 MPa | 21.6 kJ/m² | 69 °C | 1.25 g/cm³ |
| ASA | 37 MPa | 31 MPa | 65 MPa | 19.6 kJ/m² | 100 °C | 1.05 g/cm³ |
| PAHT-CF | 88 MPa | 64 MPa | 140 MPa | 22.8 kJ/m² | 194 °C | 1.06 g/cm³ |
| PET-CF | 74 MPa | 35 MPa | 131 MPa | 8.6 kJ/m² | 205 °C | 1.29 g/cm³ |
| PPA-CF | 168 MPa | n/a | 208 MPa | n/a | 227 °C | 1.25 g/cm³ |
Typical values from test specimens printed at 100% infill, annealed and dried before testing (ISO 527, ISO 178, ISO 179, ISO 75). Real parts vary with geometry, infill, orientation and moisture, and nylon-based materials lose some stiffness when they absorb moisture. Not for specification purposes.
For comparison, our MJF PA12 is about 48 MPa in every direction, with an HDT of 175 °C at 0.45 MPa.
FDM or MJF?
We run both, so we can recommend whichever suits your part rather than whichever machine we own.
| FDM | MJF PA12 | |
|---|---|---|
| Best for | One-offs, larger simple parts, specific materials | Complex parts, batches and production |
| Materials | PETG, ASA, and carbon fibre nylon, PET and PPA | PA12, flexible TPA, full-colour CB PA12 |
| Strength | Strongest along the layers, weaker between them | Near-equal strength in all directions |
| Finish | Layer lines as printed, smoothed by our vapour polishing (all FDM materials) | Fine detail, no supports; vapour polishing available |
| Outdoor / UV | Excellent in ASA | Good, and better with dyeing or Cerakote |
| High temperature | Carbon fibre nylon, PET and PPA | PA12 up to 175 °C HDT at 0.45 MPa |
| Ordering | By enquiry | Instant online quote |
Typical FDM applications
- Jigs, fixtures, gauges and assembly aids
- Outdoor housings, covers and brackets in ASA
- Stiff, lightweight carbon fibre tooling and brackets
- High-temperature parts in PPA-CF, PET-CF and PAHT-CF
- Everyday functional parts and enclosures in PETG
- Larger prototypes and enclosures, vapour polished for presentation
- Tough clips, hinges and wear parts in PAHT-CF
Designing for FDM
- Think about load direction: FDM parts are weakest between layers (see the Z column above), so tell us how the part is loaded and we'll orient it to suit.
- Overhangs: keep overhangs to about 45° or steeper where you can, to avoid support marks.
- Walls: walls of 1.2 mm or more print well; thicker walls add strength more than extra infill does.
- Corners: add fillets to inside corners and small chamfers to bottom edges for stronger, cleaner parts.
- Holes and fits: small holes print slightly undersize, so allow for reaming or tell us the fit you need.
- Threads: use heat-set or screw-in inserts for threads that will be used repeatedly. See TN-003.
- Vapour polishing: sharp edges and fine details soften slightly, so allow for this on critical features.
Not sure if your part suits FDM or MJF? Send us the file and we'll advise. Our design advice is free.
Frequently asked questions
What is FDM 3D printing?
FDM (fused deposition modelling), also called FFF, melts a plastic filament and lays it down layer by layer to build a part. It is a cost-effective way to make functional parts in a wide range of engineering plastics and composites.
Can you get rid of the layer lines on FDM parts?
Yes. Our vapour polishing smooths layer lines and seals the surface, giving FDM parts a much more finished, moulded look. It is available on every FDM material we offer, and it is one of the main reasons customers come to us for FDM.
Is FDM as strong as MJF?
Along the layers, carbon fibre composites are stronger and stiffer than MJF PA12. Between the layers FDM is weaker, whereas MJF parts are close to equally strong in every direction. We'll recommend the best process for how your part is loaded.
Which FDM material is best for outdoor use?
ASA. It keeps its colour and strength in sunlight and weather better than most other filaments.
Which FDM material is best for high temperatures?
PPA-CF is our highest heat-resistance filament (HDT around 227 °C), followed by PET-CF and PAHT-CF. PETG is not suited to hot environments. Tell us the operating temperature and load and we'll advise.
How do I order FDM parts?
FDM is quoted by enquiry. Send your STEP file (preferred) or STL through our contact page or call 01256 533838, and tell us the material, quantity, finish and what the part does.