5 )Cold Extrusion(manufacturing)
Cold extrusion forms a part of some
length by plastic flow of metal under compressive
stress into an opening of limited size. The process
is normally referred to as impact extrusion when
non-ferrous metals are involved and cold extrusion
when the workpiece is ferrous. A blank is placed in
the die and a punch puts pressure on the blank,
causing metal to flow in the desired direction. The
press used can be either mechanical or hydraulic.
With the rapid force of a mechanical press, the
term, “impact extrusion” is appropriate. There are
three varieties of the process: forward extrusion,
backward extrusion and combined extrusion.
Impactlcold extrusion produces parts with smooth
surfaces, with no loss of material in the form of
machining chips. The process is fairly rapid and is
suitable for mass-produced components used in
quantities of 100,000 pieces per year or more.
Cylindrical and near-cylindrical shapes are typical
parts made with the process. Collapsible metal
tubes are made with the process. Aluminum, cop-
per, lead, and magnesium alloys are the most com-
monly extruded, along with low and medium-carbon
steels
Handbook of Manufacturing Processes, James G. Bralla, p:74
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there is no old definition
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