Sheet Metal Fabrication Services — Complete Guide

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.

Sheet Metal Fabrication Processes

Laser Cutting

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

Plasma Cutting

Uses an electrically conductive gas jet. Best for thicker plates where laser cost is prohibitive.

• Cutting thickness: up to 150mm
• Tolerance: ±0.5-1.0mm
• Cost: Lower than laser for thick material

Waterjet Cutting

Uses high-pressure water (60,000 PSI) with abrasive garnet. Cuts any material without heat-affected zone (HAZ).

• Cuts metals, composites, stone, glass, rubber
• No thermal distortion — ideal for heat-sensitive materials
• Tolerance: ±0.1-0.2mm
• Slower and more expensive than laser for most metals

Punching & Forming

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 |

Bending

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 |

Welding & Assembly

• MIG welding: Most common for steel, fast
• TIG welding: For aluminum, stainless, thin materials — cosmetic quality
• Spot welding: Fast, automotive/mass production
• Stud welding: For mounting threaded studs
• Riveting: Alternative to welding, no heat distortion

Material Selection

Common Sheet Metals

| 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 |

Design Guidelines

Minimum Bend Radius

| 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× |

Hole & Slot Guidelines

• Minimum hole diameter: 1.0× material thickness (punching)
• Distance from hole to edge: 2× material thickness minimum
• Distance from hole to bend: 3× material thickness + bend radius minimum
• Slot width: minimum 2× material thickness

Flange & Tab Guidelines

• Minimum flange length: 4× material thickness
• Tab width: minimum 2× material thickness
• Distance from tab to edge: 2× thickness minimum

Relief Cuts

• Required at intersection of bends to prevent tearing
• Relief notch width: 1.5× material thickness minimum
• Relief notch depth: bend radius + 0.5mm minimum

Surface Finishes

| 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 |

Tolerances

| 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 |

Cost Factors

| 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 |

Design for Manufacturing (DFM) Tips

• Use standard material gauges — custom gauges cost more and extend lead times
• Keep internal radii consistent — simplifies tooling, reduces setup time
• Avoid tight tolerances where possible — sheet metal naturally has more variation than CNC
• Design for nesting — efficient layout reduces waste; odd-shaped parts waste up to 30%
• Use the same thickness throughout an assembly — fewer material changes = lower cost
• Place tolerances on one side — bilateral tolerances are harder to hit than unilateral
• Add holes for assembly alignment — prevents welding distortion from pulling assemblies out of spec

Sheet Metal vs Alternative Processes

| 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 |

Why MFGABC for Sheet Metal Fabrication?

• Equipment: Fiber laser up to 6kW, CNC press brakes 100-400 tons, turret punch press
• Materials: Mild steel, galvanized, stainless 304/316, aluminum 5052/6061, copper, brass
• Thickness range: 0.3mm to 12mm (mild steel), 0.5mm to 6mm (stainless and aluminum)
• Finishing: Powder coating line (RAL color matching), wet paint, galvanizing (outsourced but managed)
• Quality: ISO 9001:2015, inspection reports with every order
• Assembly: MIG/TIG welding, stud welding, riveting, hardware insertion (helical inserts, PEM nuts)
• Lead time: Standard 7-15 working days

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