3D printing · process family

FDM / FFF

Material extrusion · FDM · FFF · FGF

Melt a filament and lay it down road by road

By far the most common way to 3D print. A thermoplastic filament is pushed into a hot nozzle, melted, and laid down as a thin road that fuses to the road beside it and the layer below. Build the part up road by road, layer by layer. It is cheap, the material range runs from PLA to PEEK, and large build volumes are affordable — which is why it dominates both the desktop and a growing share of the factory floor.

melt · lay · fuse
FDM / FFF — melt a filament and lay it down road by road.
0.1–0.3 mm layers
Resolution
Moderate–fast
Speed
$ (lowest)
Cost
Poor (Z ≈ 30–70% of XY)
Isotropy

How it works

  1. 1
    A drive gear pushes filament into a heated nozzle (the hot end).
  2. 2
    The melt is extruded as a thin road and deposited along the toolpath.
  3. 3
    Each road fuses to its neighbours and to the layer beneath by partial re-melting.
  4. 4
    The bed (or nozzle) steps down one layer height and the next layer is drawn.
  5. 5
    Overhangs beyond ~45° are held up by sacrificial support structures.

The machines

The variants of this family, from the hobby basics to the industrial state of the art.

Bed-slinger (Cartesian)

Hobby

The bed moves in Y while the head moves in X and Z. The cheap, ubiquitous desktop layout (Ender-class).

CoreXY

Prosumer

Both X and Y are driven by two fixed motors and a crossed belt; the bed only moves in Z. Lighter, faster, more accurate at speed.

Delta

Prosumer

Three arms on vertical towers move a light effector. Fast, tall, good for round parts.

IDEX / tool-changer

Prosumer / pro

Two independent heads (or swappable tools) for dual-material, soluble supports, or mirror/duplicate printing.

Pellet extrusion (FGF / BAAM)

Industrial

Feeds cheap plastic pellets through a screw extruder instead of filament — the route to large-format and high-throughput printing (boat hulls, tooling).

Continuous-fibre

Industrial

Co-deposits a continuous carbon or glass fibre tow inside the thermoplastic to reach near-aluminium stiffness (Markforged-style).

Strengths & limits

Strengths
  • Cheapest hardware and material
  • Widest material range of any process, PLA to PEEK
  • Large build volumes are affordable
  • Easy multi-material and soluble supports
Limits
  • Visible layer lines; a rougher surface than resin or powder
  • Strongly anisotropic — weak between layers (the Z direction)
  • Overhangs need supports that leave marks
  • Warping on high-shrinkage polymers (ABS, PA, PC) without a heated chamber

Typical parts & materials

Feedstock: Filament (1.75 / 2.85 mm) or pellets · Thermoplastics — remeltable.

Typical parts: Prototypes, jigs and fixtures, low-volume functional parts, large tooling

Commonly run in — open one for its cited properties:

PLAPETGABSTPUNylon (PA)PCPEEKPEI (Ultem)PPS

What's new

High-speed printing is the story of the last few years: input shaping and pressure advance (Klipper) plus stiff CoreXY frames pushed reliable speeds from ~60 to 300–600 mm/s. Automatic multi-colour/multi-material feeders (AMS-style) and cheap continuous-fibre and high-temp (PEEK/PEI) machines are the other frontiers.

Part of the 3D printing guide. Compare the other process families, see the design rules, or browse the cited materials database.