Manufacturing
3D Printing (FDM)
Fused Deposition Modeling — extrude thermoplastic layer by layer
Fused Deposition Modeling (FDM) builds parts by extruding heated thermoplastic filament through a nozzle that traces each layer's geometry onto a build plate. Invented by Scott Crump (Stratasys, 1989). Layer thicknesses typically 0.1–0.3 mm. Common materials: PLA, ABS, PETG, nylon, polycarbonate. Strengths: cheap, accessible, large build volumes possible. Weaknesses: visible layer lines, anisotropic strength, limited detail. Dominant consumer 3D printing technology after key patents expired in 2009.
- InventedScott Crump, Stratasys, 1989
- Layer height0.1–0.3 mm typical
- MaterialsPLA, ABS, PETG, nylon, PC
- Nozzle temp180–280°C
- AnisotropyZ-axis weakest direction
- Patent expiry2009 — sparked RepRap movement
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Why FDM matters
- Prototyping. Days-to-hours iteration cycle.
- Tooling. Custom jigs, fixtures, end-of-arm tooling.
- Education. Accessible price unlocks classroom CAD-to-part learning.
- Spare parts. On-demand production for legacy hardware.
- Customization. Prosthetics, orthotics, ergonomic grips.
- Aerospace. Lightweight non-structural cabin parts in PEEK and ULTEM.
- Hobbyist ecosystem. RepRap community, open-source firmware.
Common misconceptions
- Strength matches injection molding. Layer interfaces remain weakest plane.
- Any geometry works. Overhangs, bridges, fine features have hard limits.
- One filament fits all. PLA brittle outdoors; ABS warps without enclosure.
- Higher resolution always better. Smaller layers multiply print time non-linearly.
- Infill = strength. Wall count and orientation matter more than internal lattice.
- Print and ship. Most parts need cleanup, support removal, or post-cure.
Frequently asked questions
How does FDM work?
Filament feeds into a heated extruder where it melts. A nozzle deposits the molten thermoplastic onto a build plate, tracing the slice geometry. The plate or nozzle moves on Z axis between layers. Layer height (0.1–0.3 mm) controls vertical resolution. Cooling fans solidify each pass before the next is laid.
Why is FDM anisotropic?
Layers bond by partial fusion as new material melts the surface below. The interlayer bond is weaker than continuous polymer. Tensile strength along the print plane (XY) can be 2–3× stronger than across layers (Z). Designers orient parts so loads run along filament tracks, not across layer interfaces.
What materials work best?
PLA prints easily at low temps (200°C) and warps minimally — best for prototypes. ABS is tougher and heat-resistant but warps without enclosed chambers. PETG balances ease and strength. Nylon and polycarbonate offer engineering-grade properties but require dry filament and higher temps. Carbon-fiber-filled variants add stiffness.
What's slicing?
Software (Cura, PrusaSlicer, Bambu Studio) converts a 3D model into G-code: nozzle paths, temperatures, and movement speeds for each layer. Slicing decisions — infill density, perimeter count, support placement, cooling — determine print time, strength, and surface finish. Tuning slicer profiles per material is essential.
How accurate is FDM?
Dimensional accuracy typically ±0.2 mm on consumer machines, ±0.05 mm on industrial. Surface finish shows visible layer lines (Ra 10–30 μm). Tight tolerances (sub-0.1 mm) require post-machining. Stringing, elephant's foot, and over-extrusion add error. Sub-millimeter holes shrink and often need drilling.
When is FDM better than SLA or SLS?
FDM wins for: cost (filament cheap), large parts (build volumes up to 1m³), engineering plastics, no resin handling. SLA wins for: detail, smooth surfaces, jewelry. SLS wins for: complex geometries with no supports, isotropic strength. Choice depends on tolerance, surface, and material requirements.
What about supports?
Overhangs steeper than 45° need support material or they sag. Slicer auto-generates supports — sacrificial structures removed after printing. Soluble supports (PVA, BVOH) dissolve in water for clean removal but require dual-extruder printers. Designing parts to avoid supports — chamfering overhangs, splitting models — saves material and time.