Forging

Forging plastically deforms metal under compressive force to create high-strength, directional-grain parts, often near-net-shape with secondary machining.

Overview

Forging forms metal by plastic deformation under compressive force (hammer, press, or rolling) to produce dense parts with aligned grain flow. Common variants include open-die and closed-die forging, cold forging, upset forging, and ring rolling. The result is typically higher strength, toughness, and fatigue performance than comparable wrought stock or cast shapes.

Choose forging when mechanical performance matters and the geometry can be formed with draft, radii, and controlled parting lines. It fits medium to high volumes where tooling cost amortizes, and it’s also used for low-volume large components via open-die. Tradeoffs: die cost and lead time, geometry limits (thin walls, deep pockets), and added ops like trimming, heat treat, and machining to hit tight tolerances and features.

Common Materials

  • Steel 4140
  • Steel 4340
  • Stainless 316
  • Aluminum 7075
  • Titanium Ti-6Al-4V
  • Inconel 718

Tolerances

±0.010" to ±0.030" (as-forged); tighter with machining

Applications

  • Crankshafts
  • Connecting rods
  • Gear blanks
  • Aircraft landing gear components
  • Flanges and fittings
  • Bearing rings

When to Choose Forging

Pick forging for load-bearing parts where fatigue life, impact toughness, and reliability drive the design. It’s a strong fit when you can accept forging-friendly geometry (draft/radii/parting line) and plan for secondary machining. Volumes range from one-off large open-die forgings to high-volume closed-die or cold-forged components.

vs Stamping

Choose forging when the part needs substantial thickness, 3D mass distribution, and high fatigue/impact performance from grain flow. Stamping fits thin sheet geometries; forging fits solid sections like hubs, blanks, and structural lugs, usually followed by machining.

vs Extrusion

Choose forging when the cross-section must change along the length, or when localized thick sections and directional grain flow around features matter. Extrusion is best for constant cross-sections; forging handles transitions, bosses, and near-net preforms for critical strength.

vs Wire Forming

Choose forging when you need solid-section strength, tight control of metallurgical properties, and robust interfaces for machining, press fits, or splines. Wire forming suits spring-like geometries from wire/rod; forging suits compact, high-load shapes and bearing surfaces.

vs Casting

Choose forging when porosity risk and fatigue performance are primary concerns and the geometry can be simplified for forming. Casting allows more complex internal features and thin-wall shapes, but forged parts typically deliver higher toughness and consistency.

Design Considerations

  • Add draft on die-formed surfaces and define the parting line early to control flash and trimming
  • Use generous fillets and corner radii to improve metal flow and reduce die wear and laps
  • Avoid thin webs, deep pockets, and sharp section changes; plan to machine detailed features instead
  • Specify critical datums and allow machining stock on bearing surfaces, seals, and interfaces
  • Call out heat treat condition and any required grain-flow direction if it impacts performance
  • Provide target as-forged shape or machining envelope so the forge can size preforms and quote accurately