FDM — Fused Deposition Modeling
The most accessible and cost-effective 3D printing process — melts plastic filament layer by layer to build functional parts fast.
FDM
Fused Deposition Modeling
From filament to finished part
- STL file is sliced into layers, generating the nozzle toolpath.
- Filament feeds into a heated nozzle — melted to 180–260°C.
- Nozzle moves in X and Y, depositing molten plastic layer by layer.
- Build plate drops one layer height — next layer fuses on top.
- Overhangs printed with supports — removed by hand after printing.
What FDM is great at — and where it falls short
- Lowest cost per part of any 3D printing process
- Widest material selection — PLA, PETG, ASA, ABS, TPU, Nylon
- Largest build volumes available (up to 300×300×400 mm)
- Same-day turnaround possible for small parts
- Easy to iterate and reprint
- Cost-effective for large parts
- Visible layer lines on every surface
- Weaker in the Z (build) direction — anisotropic
- Not suitable for features below ~0.5 mm
- Support marks left on overhangs
- Warping risk on large flat parts (especially ABS)
- Not watertight without sealing
When to choose FDM
- You need a functional prototype fast and affordably.
- You need a large part (over 200 mm in any dimension).
- You need a flexible material (TPU) or a UV-stable outdoor material (ASA).
FDM materials we stock
Real mechanical properties so you can match material to application.
| Material | Tensile Strength | Heat Resistance | Elongation at Break | Density | Finish | Best For | Limitations |
|---|---|---|---|---|---|---|---|
| PLA | 50 MPa | 60 °C | 6% | 1.24 g/cm³ | Matte | Visual prototypes, display models | Brittle, low heat resistance |
| PETG | 53 MPa | 75 °C | 50% | 1.27 g/cm³ | Semi-gloss | Functional parts, containers | Stringy, needs tuning |
| ASA | 55 MPa | 95 °C | 4% | 1.07 g/cm³ | Matte | Outdoor & UV-exposed parts, automotive | Higher warping risk |
| TPU (95A) | 39 MPa | 80 °C | 450% | 1.21 g/cm³ | Matte | Grips, gaskets, protective cases | Slow to print, stringy |
The numbers that matter
What tolerance means in practice: ±0.5 mm means if you design a hole 10 mm wide, the printed part may come out anywhere between 9.5 mm and 10.5 mm. That's fine for most enclosures and brackets, but if you're fitting a bearing or threading a bolt, you'll want to either oversize the hole and post-drill, or move to SLA (±0.15 mm) or SLM with post-machining (±0.025 mm).
Five rules that save reprints
Wall Thickness
Minimum wall: 1.2 mm for structural walls, 0.8 mm for cosmetic walls only.
Why: thinner walls bond poorly between layers and crack under load.
Overhangs
Overhangs above 45° from vertical need support material — which leaves marks.
Why: support material always leaves a slightly rougher patch where it touches the part.
Hole Sizing
Add 0.2 mm to designed diameter for vertical holes, or post-drill for tight fits.
Why: vertical holes shrink slightly because the inner walls cool inwards.
Clearance for Assemblies
Allow 0.4–0.6 mm clearance between mating parts.
Why: FDM tolerance stack-up between two parts can easily reach 0.3–0.5 mm.
Print Orientation for Strength
Orient your part so the main load axis runs across layers (XY), not along Z.
Why: layer-to-layer adhesion is the weakest link — Z-direction strength is ~50% of XY.
How FDM stacks up
| Property | FDM | SLA | SLS | MJF | SLM |
|---|---|---|---|---|---|
| Cost | $ | $$ | $$$ | $$$ | $$$$$ |
| Surface Finish | Visible layers | Near-smooth | Slightly grainy | Slightly grainy | Rough as-printed |
| Detail | Moderate | Excellent | High | High | High |
| Tolerance | ±0.5 mm | ±0.15 mm | ±0.3 mm | ±0.2 mm | ±0.2 mm |
| Strength | Anisotropic | Near-isotropic | ~85% iso | ~95% iso | Near-isotropic |
| Speed | Fast | Medium | Medium | Fast | Slow |
| Material Range | Wide (PLA, PETG, ASA, TPU…) | Resins | PA12, PA12GB | PA12, PA12GB, TPU | Al, SS, Ti, tool steel |
| Support-free | No | No | Yes | Yes | No |
| Best for | Prototypes & big parts | Visual & detail | Complex geometry | Production batches | Metal end-use |
Key Applications
Rapid Prototyping
Functional prototypes for engineering review.
Speed and low cost make iteration affordable.
Jigs & Fixtures
Custom workshop tooling and assembly aids.
PETG/ASA durability matches the use case.
Enclosures & Housings
Electronics housings, brackets, mounts.
Low cost per unit, easy to revise.
Educational Models
Anatomical, mechanical, and architectural teaching aids.
PLA is safe, low-cost, and prints reliably.
Architectural Mock-ups
Large massing models and presentation pieces.
Largest build envelope per dollar.
Consumer Products
Custom one-offs, replacement parts, hobby builds.
Wide material choice covers nearly any use case.
FDM, answered
Yes — especially in PETG, ASA, and Nylon for non-cosmetic applications. PLA is best left to visual or indoor-only end-use.
Layer lines are most visible on curved surfaces and top faces. Sanding or priming evens out the appearance. SLA is the answer if surface aesthetics are critical.
Roughly 50–70% the strength of injection-moulded equivalents in the XY plane. The Z-direction is weaker because layer-to-layer bond is the weakest link.
Not on standard FDM. Painting after printing is the practical option for multi-colour finishes.
Not by default. Walls need to be ≥3 perimeters thick and sealed with epoxy for liquid containment. For inherent watertightness, use SLS or MJF.
STL, OBJ, or STEP. We recommend STEP for functional parts because it preserves precise CAD geometry.