Cold Metal Extrusion

Cold metal extrusion forms metal at or near room temperature through a die, producing high-strength parts with good finish and repeatability at volume.

Overview

Cold metal extrusion pushes a billet or slug through (or around) a die at or near room temperature to create long profiles or near-net shapes. Because deformation happens cold, parts gain significant work hardening, good surface finish, and tight repeatability, with minimal material waste compared to machining.

Choose it for high-volume production of axisymmetric or prismatic shapes where strength, concentricity, and consistent dimensions matter—fasteners, sleeves, small housings, and preforms for secondary machining. Tooling cost is the gating item; it pays off when you can amortize dies and presses over large quantities.

Tradeoffs: geometry must support straight-line metal flow; deep features, sharp corners, and abrupt section changes drive high forces and die wear. Material ductility at room temperature limits what can be extruded, and press capacity can cap size. Expect some springback control, potential residual stresses, and the need for trimming, coining, heat treat, or finish machining for critical features.

Common Materials

  • Aluminum 6061
  • Aluminum 1100
  • Copper C110
  • Brass 360
  • Steel 1018
  • Stainless 304

Tolerances

±0.003" to ±0.010"

Applications

  • Aluminum heat sink and structural profiles
  • Cold-extruded fastener blanks and rivet bodies
  • Bushings and bearing sleeves
  • Electrical connector terminals and lugs
  • Small cylindrical housings and cups
  • Preforms for finish machining (near-net rings and sleeves)

When to Choose Cold Metal Extrusion

Cold metal extrusion fits parts with largely constant cross-sections or straightforward axisymmetric forms that can be produced in one metal-flow direction. It makes sense when volumes are high enough to justify tooling and you want strong, repeatable parts with low scrap. Plan on secondary ops for threads, tight bores, critical faces, or features not aligned with the extrusion direction.

vs Hot Metal Extrusion

Choose cold metal extrusion when you need higher strength from work hardening, better surface finish, and tighter dimensional repeatability without oxide scale. It suits smaller parts and ductile materials where press capacity can handle the higher loads at room temperature.

vs CNC machining

Choose cold metal extrusion when the part can be formed near-net and you need lower piece price at volume with far less scrap. It also helps when material properties from cold work (strength, hardness) are desirable versus starting from bar or plate.

vs Cold heading (cold forging)

Choose cold metal extrusion when you need longer drawn lengths, thin-walled sections, or controlled internal shapes that benefit from metal flow through a die. It’s a better fit for sleeves, cups, and preforms beyond typical upset-and-form fastener geometries.

vs Metal injection molding (MIM)

Choose cold metal extrusion when the geometry is relatively simple but mechanical properties, fatigue performance, and cost at high volume are priorities. Extrusion avoids sintering shrink variability and typically delivers denser, stronger parts.

Design Considerations

  • Keep cross-section changes gradual to maintain stable metal flow and reduce die load
  • Use generous radii at corners and transitions; sharp corners spike force and shorten die life
  • Align critical features with the extrusion direction; plan secondary machining for cross-holes, undercuts, and side features
  • Specify tolerances selectively—tighten only where function demands, and define which surfaces are to be machined after extrusion
  • Call out target mechanical properties and any required heat treat/anneal since cold work can raise hardness and residual stress
  • Provide material spec, temper/condition, and annual volume up front so the shop can size press capacity and tooling correctly