Page 213 - Mechanical Engineer's Data Handbook

MANUFACTURING TECHNOLOOY 20 1

5.9.3 Extrusion

Hot extrusion
A piece of red-hot bar or billet is placed in a cylinder
and forced through a specially shaped die by a piston
to produce long lengths of bar. Hollow sections can be
made by placing a mandrel in the die orifice.
Cold extrusion

Soft metals such as aluminium and copper can be
extruded cold. Practically all metals may be extruded.

Cylinder

Aluminium archilectural ~~ctions
Billet
Hot extrusion

5.9.4 Impact extrusion
A metal which is plastic when cold may be extruded by
the impact of a high-velocity punch. The metal of the
blank flows up the sides of the punch to produce a
cylinder. The process is used for manufacturing tooth-
paste tubes, ignition coil cans, etc.

Impact extrusion