When WAAM wins
WAAM uses a GMAW or CMT welder mounted on a 6-axis robot to deposit a part wire-by-wire. Build rates exceed 1 kg/hr; envelopes are limited only by the robot. Wire is an order of magnitude cheaper than atomized powder.
Pick WAAM for ship-class fittings, large brackets, mining and offshore parts, and replacement of legacy forgings up to ~1 m.
- Parts > 500 mm in any dimension
- Mass > 50 kg
- Low-cost material is a hard requirement
- Replacement of legacy steel forgings
Defects and post-processing
WAAM deposits coarse-grain, anisotropic structures with prominent inter-pass weld marks. Surface finish is Ra 100–500 µm — machine everything that matters. Internal soundness is usually good (< 1 % porosity) but requires UT inspection on critical sections.
Stress-relief is mandatory; normalizing improves toughness.
Suggested parameters
Starting recipe on a CMT-based WAAM cell.
- Wire diameter: 1.2 mm
- Travel speed: 6–10 mm/s
- Wire feed: 4–8 m/min
- Inter-pass temperature: < 150 °C
- Shield gas: Ar + 18% CO₂
Frequently asked questions
Is WAAM a real AM process or just robotic welding?
Both. The mechanics are MIG welding; the discipline (layered toolpaths, inter-pass temperature control, machining stock allowance) is AM. Standards now exist (AWS D20.1, ISO/ASTM 52928).
What's the surface like?
Very rough — visible weld beads, Ra in the hundreds of microns. WAAM parts always need machining on functional surfaces.
Sources
- AWS D20.1 — Specification for Fabrication of Metal Components using AM
- ISO/ASTM 52928 — Feedstock Materials
- Lloyd's Register Guidance Notes for Metallic AM