Sheet metal fabrication is a manufacturing process that transforms flat metal sheets into functional parts and enclosures through cutting, bending, forming, and joining. It's widely used for enclosures, brackets, panels, frames, and structural components across industries.
This guide covers sheet metal processes, design guidelines, material selection, finishes, tolerances, and cost optimization.
A high-power laser beam cuts through metal sheet with precision. The most common cutting method in modern fabrication.
| Laser type | Best for | Max thickness (steel) | Edge quality |
|---|---|---|---|
| Fiber laser | Most metals (steel, SS, Al, Cu, brass) | 25mm (mild steel) | Excellent — dross-free up to 12mm |
| CO2 laser | Non-metal; good edge on thicker steel | 20mm | Good — slightly wider kerf |
Advantages: High precision (±0.1mm), narrow kerf (0.1-0.3mm), no tooling cost, fast turnaround
Uses an electrically conductive gas jet. Best for thicker plates where laser cost is prohibitive.
Uses high-pressure water (60,000 PSI) with abrasive garnet. Cuts any material without heat-affected zone (HAZ).
A CNC turret punch press creates holes, slots, louvers, and forms using interchangeable tooling.
| Process | Feature | Typical tool |
|---|---|---|
| Punching | Round holes, slots | Round punch |
| Nibbling | Irregular shapes | Small rectangular punch |
| Louvering | Airflow vents | Louver tool |
| Countersinking | Flush screw heads | Countersink tool |
| Extruding | Threaded holes | Extrude tool |
| Embossing | Raised features | Emboss tool |
CNC press brakes bend sheets along straight lines to form 3D shapes.
| Bend type | Description |
|---|---|
| Air bending | Most common — punch does not bottom out |
| Bottom bending | Sheet pressed into v-die — higher accuracy |
| Coining | Punch forces material into die — highest accuracy, highest force |
| Material | Thickness range (mm) | Strength | Corrosion resistance | Relative cost | Typical use |
|---|---|---|---|---|---|
| Mild steel (DC01/SPCC) | 0.5-6.0 | Good | Poor (needs coating) | $ | Enclosures, brackets, frames |
| Galvanized steel (DX51D/SGCC) | 0.5-3.0 | Good | Good (zinc coating) | $ | Outdoor enclosures, ductwork |
| Stainless steel 304 | 0.5-6.0 | Good | Excellent | $$$ | Food equipment, medical, marine |
| Stainless steel 316 | 0.5-6.0 | Good | Superior | $$$$ | Chemical, pharmaceutical, coastal |
| Aluminum 5052 | 0.5-6.0 | Moderate | Good | $$ | Electronics, marine, automotive |
| Aluminum 6061 | 0.8-6.0 | Good | Good | $$ | Structural, aerospace (less formable than 5052) |
| Copper | 0.3-3.0 | Moderate | Good | $$$$ | Electrical, decorative |
| Brass | 0.3-3.0 | Moderate | Good | $$$ | Decorative, electrical |
| Material | Minimum bend radius (× thickness) |
|---|---|
| Mild steel (soft) | 0.5-1.0× |
| Mild steel (hard) | 1.0-2.0× |
| Stainless steel | 1.5-2.5× |
| Aluminum 5052 | 0.8-1.5× |
| Aluminum 6061 | 2.0-3.0× (bends poorly, may crack) |
| Copper/Brass | 0.5-1.0× |
| Finish | Description | Typical use | Cost impact |
|---|---|---|---|
| Mill finish | As-rolled surface | Hidden parts, secondary operations | None |
| Powder coating | Durable colored coating | Outdoor enclosures, machinery | Medium |
| Paint (wet spray) | Lower cost than powder | Large parts, low volume | Low-medium |
| Galvanizing (HDG) | Hot-dip zinc coating | Outdoor structures, lattice | Medium |
| Anodizing | Aluminum only, colored | Electronics, cosmetics | Medium |
| Brushed/grained | Linear finish | Decorative panels, appliances | Low |
| Mirror polish | High-gloss | Architectural, decorative | High |
| Passivation | Stainless only | Medical, food equipment | Low |
| Electro-polishing | Smooth, bright, clean | Medical, pharmaceutical | Medium |
| Feature | Standard (±mm) | Precision (±mm) |
|---|---|---|
| Laser cut dimensions | 0.2 | 0.1 |
| Punching | 0.15 | 0.1 |
| Bending angle | ±1° | ±0.5° |
| Fold-to-fold distance | 0.25-0.5 | 0.15 |
| Hole-to-edge after bending | 0.35-0.5 | 0.2 |
| Welded assembly | 0.5-1.0 | 0.3-0.5 |
| Factor | Cost impact | Why |
|---|---|---|
| Material gauge | 1.5-3× | Thicker sheets require more power, heavier tooling |
| Complexity (bends) | 1.2-2× | Each bend needs handling time and setup |
| Tolerance | 1.3-2× | Precision requires slower feed, more checking |
| Quantity | 1.5-5×/unit | Setup cost spread; high volume = lower unit cost |
| Surface finish | 1.2-3× | Powder coating, plating, polishing add processes |
| Welding | 1.3-2× | Skilled labor, inspection, potential rework |
| Factor | Sheet Metal | CNC Machining | 3D Printing |
|---|---|---|---|
| Best quantity | 10-10,000+ | 1-1,000 | 1-100 |
| Part envelope | Large (2m+ panels) | Limited by machine | Limited by build volume |
| Strength-to-weight | Excellent | Good | Moderate |
| Material options | Limited (thin sheets) | Extensive | 20-50 polymers |
| Surface finish | Post-processing needed | Excellent out of machine | Post-processing needed |
| Initial tooling cost | Low (no mold) | Low (no mold) | None |
| Unit cost at 1,000 pcs | Very low | Moderate | High |
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