Extrusion

Extrusion forces metal through a die to form long, constant-profile shapes with efficient material use and good surface finish at medium to high volumes.

Overview

Extrusion forms metal by pushing a billet through a shaped die to create long parts with a constant cross-section, such as channels, tubes, and complex profiles. Hot extrusion runs material above recrystallization temperature for heavier sections, while cold extrusion forms at or near room temperature for better strength, surface finish, and dimensional control.

Choose extrusion when your part is essentially a 2D profile extended in one direction and you need repetitive lengths cut from that profile. It shines for medium to very high volumes, structural shapes, and integrated features that would be expensive to machine from solid. Expect moderate dimensional accuracy directly off the press and plan for secondary machining on critical interfaces or tight fits. Tooling (dies) is a one-time cost but usually modest compared to many forming processes, making custom profiles practical when you can amortize the die cost over a production run.

Common Materials

  • Aluminum 6061
  • Aluminum 6063
  • Steel 1018
  • Stainless Steel 304
  • Copper
  • Brass

Tolerances

±0.005" to ±0.010" on profile dimensions; tighter features via secondary machining

Applications

  • Heat sink extrusions and electronic enclosures
  • Window and door frames
  • Structural channels, angles, and rails
  • Automotive trim and roof rails
  • Tubing and hollow profiles
  • Guide rails and conveyor profiles

When to Choose Extrusion

Use extrusion for long parts with a uniform cross-section where you can cut multiple finished lengths from a single profile run. It fits medium to high production volumes, moderate tolerances, and profiles that benefit from integrated features like channels, fins, and hooks. It is especially effective when material utilization and reduced machining time matter.

vs Forging

Choose extrusion instead of forging when your part is essentially a prismatic profile and you need long, constant cross-sections in higher quantities. Forging suits discrete, thicker, 3D shapes; extrusion is more economical and flexible for linear profiles with integrated features.

vs Stamping

Choose extrusion over stamping when you need 3D profiles with thickness in the extrusion direction, such as channels, tubes, and fins, rather than flat sheet parts. Extrusion handles deeper sections, varying wall thickness, and complex edge geometry that would require multiple stampings and forming operations.

vs Wire Forming

Choose extrusion instead of wire forming when you need non-round or complex profile shapes, or larger cross-sections than typical wire sizes. Wire forming is best for bending pre-made wire; extrusion creates the custom cross-section itself before any forming or bending steps.

vs CNC machining

Choose extrusion over CNC machining when your geometry can be expressed as a constant cross-section and your volume justifies a die. Extrusion lets you buy or produce near-net profiles and then lightly machine only critical areas, dramatically cutting cycle time and material waste compared to machining from solid bar or plate.

Design Considerations

  • Keep wall thickness as uniform as possible and avoid abrupt thickness transitions to reduce die stress and distortion
  • Use generous internal and external radii instead of sharp corners to improve flow and die life
  • Limit very thin fins and deep narrow slots; check feasible aspect ratios with the extrusion house early
  • Clearly distinguish critical tolerances from reference dimensions so the extruder knows where to control and where standard tolerances are acceptable
  • Specify straightness, twist, and cut-length requirements realistically; over-tight specs can drive unnecessary secondary operations
  • Plan for secondary machining on tight fits, holes, and sealing surfaces rather than trying to hold machining-level tolerances directly off-extrusion