Metal Fabrication for Prototypes and Production
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Fabrication makes metal parts by cutting, bending and joining sheet, plate, tube and bar. Most fabrication processes need little part-specific tooling, so the same methods can make a single prototype or a production run, with fixtures and dies added as quantities grow.
Prototypes
Laser cutting and press brake bending make flat and formed sheet metal parts directly from a CAD model, usually within days. Prototype welded assemblies are typically tacked up on a welding table or in a simple fixture. This makes fabrication a quick way to check fit and function before production.
Production
- Welding fixtures locate the parts so every assembly comes out the same and welding goes faster.
- Progressive or transfer dies replace laser cutting and bending once volumes are high enough to pay for the die.
- Robotic welding takes over repetitive welds at higher volumes.
- Inspection moves from checking each part to sampling plans and checking fixtures.
Typical tolerances
Laser-cut profiles are commonly held to about ±0.1 to ±0.2 mm. Bending adds variation, typically ±0.2 to ±0.5 mm on formed dimensions and ±0.5° to ±1° on bend angles. Welded assemblies distort as they cool, so critical features are often machined after welding.
Materials
Most fabricated parts are mild steel, stainless steel or aluminum. Chromoly and titanium tube are used for motorsport and lightweight structures, and titanium needs full inert gas shielding when welded.
See metal fabrication.