Forming

Forming shapes sheet metal with bending and rolling to create flanges, channels, and profiles without removing material, ideal for efficient structural features.

Overview

Forming in sheet metal fabrication reshapes flat blanks into three-dimensional parts using press brakes, rolls, and hemming tools. The material is plastically deformed along straight or curved lines to create flanges, channels, boxes, panels, and stiffening features without removing material. Sub-processes include press brake bending for sharp angles, roll bending for large radii and curves, and hemming for safe, reinforced edges.

Use forming when you need strong, repeatable features from flat stock with minimal waste and fast cycle times. It excels for brackets, enclosures, panels, and structural features at low to high production volumes, once a flat pattern is defined. Tradeoffs include bend-radius and flange-length limits imposed by tooling, bend-induced dimensional variation, and the need to account for bend allowances in the flat pattern. Very tight tolerances across multiple bends or deep box geometries may require careful setup, specialty tooling, or secondary operations.

Common Materials

  • Mild steel CRS
  • Stainless steel 304
  • Stainless steel 316
  • Aluminum 5052
  • Aluminum 6061
  • Galvanized steel

Tolerances

±0.005" to ±0.015" on formed dimensions; ±0.5° to ±1° on bend angles

Applications

  • Mounting brackets with multiple bends
  • Sheet metal electrical enclosures
  • Rack-mount chassis and cabinets
  • Stiffened machine panels and guards
  • U-channels and hat channels
  • Rolled rings, arcs, and curved panels

When to Choose Forming

Use forming when your part can start as a flat sheet and gain its strength and function from bends, flanges, and rolled profiles. It suits medium to high repeat volumes where tooling setups can be reused and consistent bend geometry is critical. It also works well for prototypes when you want production-representative parts from standard sheet stock.

vs Cutting

Choose forming over cutting when the goal is to create 3D stiffness and functional geometry from a flat blank, not just define the outline. Use cutting to create the flat pattern, then forming to add strength, flanges, and structure without increasing material thickness or weight.

vs Punching

Use forming instead of pure punching when you need height, flanges, or channels, not just holes and simple embosses. Punching is ideal to create holes and internal profiles in flat sheet, while forming converts that punched blank into a rigid 3D shape with structural bends and edges.

vs Fastening

Choose forming over adding fasteners when bend tabs, hems, or interlocking features can provide the required stiffness or joint strength without hardware. Formed features can reduce part count and assembly time, while fasteners remain useful where disassembly, service access, or very high joint strength is required.

vs Welding (Sheet Metal)

Use forming instead of welding when a single piece of sheet can be bent into shape, avoiding weld distortion, added labor, and post-weld finishing. Reserve welding for cases where geometry cannot be made from a single blank or where large assemblies require joining multiple formed components.

vs Hydroforming

Select conventional forming when you need straight-line bends, standard profiles, and fast turnaround using common press brake and roll tooling. Hydroforming becomes attractive for complex, highly contoured shapes or deep draws, but comes with higher tooling costs and longer setup times than typical sheet metal forming.

Design Considerations

  • Use a minimum inside bend radius of at least 1x material thickness (often more for stainless) to match standard tooling and reduce cracking risk
  • Define clear bend directions and grain orientation on drawings to avoid cracking or distortion along the material grain
  • Include accurate bend allowances and bend deductions in the flat pattern so formed dimensions, not flat dimensions, control fit
  • Avoid very short flanges; target flange length ≥ 3x material thickness or follow your supplier’s minimum to ensure clampability in the press brake
  • Add bend reliefs at corners where bends intersect to prevent tearing and reduce distortion in tight corner areas
  • Keep critical holes and slots at least 2–3x material thickness away from bend lines to maintain hole roundness and positional accuracy after forming