What Is Sheet Metal Fabrication?
Sheet metal fabrication turns flat metal sheets into finished parts through cutting, bending, and forming. It’s one of the most common manufacturing methods — if you’ve ever seen an electrical enclosure, a bracket, a chassis, or a duct, it started as a flat sheet.
Core Processes
Laser Cutting
A focused laser beam melts or vaporizes material along a programmed path. Modern fiber lasers cut steel up to 1″ thick and aluminum up to 0.5″ with ±0.005″ accuracy. Fast, clean edges, minimal heat-affected zone.
Plasma Cutting
Ionized gas at 30,000°F cuts through conductive metals. Less precise than laser (±0.020″) but handles thicker plate — up to 6″ steel. Lower equipment cost makes it ideal for structural work.
Waterjet Cutting
High-pressure water (60,000 PSI) with abrasive garnet cuts virtually anything — metal, stone, glass, composites. No heat-affected zone. Slower than laser but handles materials that can’t take heat.
Bending / Forming
A press brake forces sheet metal into a V-die to create bends. Modern CNC press brakes hold ±0.5° on bend angle and ±0.010″ on dimensions. Common bends: 90°, 120°, Z-bends, hems, offsets.
Punching / Stamping
A turret punch press or stamping die creates holes, louvers, and formed features at high speed. Economical for repetitive patterns. Stamping dies have high upfront cost but excel at volume.
Common Sheet Metal Materials
| Material | Common Gauges | Notes |
|---|---|---|
| Cold Rolled Steel (CRS) | 16–24 ga | Cheapest. Must be painted or plated. General fabrication. |
| Hot Rolled Steel (HRS) | 10–14 ga (thicker) | Structural. Scale surface. Weldable. |
| Galvanized Steel | 16–24 ga | Zinc-coated for corrosion. HVAC, outdoor. |
| Stainless 304 | 16–24 ga | Corrosion resistant. Food, medical, architectural. |
| Stainless 316 | 16–22 ga | Marine and chemical resistance. Premium cost. |
| Aluminum 5052 | 16–24 ga | Best formability. Enclosures, panels. |
| Aluminum 6061 | Various | Stronger but cracks when bent tight. Structural. |
Design Guidelines
- Minimum bend radius: Equal to material thickness for steel, 1.5x for aluminum
- Hole-to-edge distance: At least 2x material thickness from any bend or edge
- Hole-to-hole distance: At least 2x material thickness between holes
- Minimum flange length: 4x material thickness (otherwise the brake can’t grip it)
- Bend relief: Add a small notch where a bend meets an edge — prevents tearing
- Grain direction: Bend perpendicular to the rolling grain when possible — reduces cracking
- Flat pattern matters: Your 3D design unfolds into a flat blank. K-factor (typically 0.4–0.5) determines bend allowance. If your flat pattern doesn’t work, your part can’t be made.
PEM Hardware
Press-fit fasteners (PEM brand) installed by squeezing into a pre-punched hole. Types include:
- PEM nuts: Threaded inserts for thin sheet (self-clinching)
- PEM studs: Threaded studs pressed into sheet
- PEM standoffs: Spacers for mounting PCBs or sub-assemblies
- Captive screws: Screws that stay in the panel (access doors, covers)
PEM hardware eliminates welding nuts to sheet metal — cleaner, faster, no heat distortion.
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