extrusion and drawing - gct books · extrusion and drawing manufacturing processes. outline...
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Outline
Extrusion
Extrusion of Metals
Extrusion Defects
Extrusion Equipment
Extrusion of Nonmetals
Drawing
Drawing Process
Drawing Equipment
Extrusion
A compression process in which
the material is forced to flow
through an opening to produce
a shape with a specific cross-
section
pump
input
dieproduct
Metal Extrusion
Direct Extrusion
A ram compresses the
material, forcing it through the
die
Indirect Extrusion
The die is mounted on the ram;
the material is forced out in the
opposite direction of the ram
movement
Extrusion
Hot Extrusion
Involves pre-heating the
material above the
recrystallization temperature to
increase ductility
Cold Extrusion
Does not pre-heat material;
used to produce parts in
finished or near-finished form
Extrusion
Cold extrusion advantages:
- Improved mechanical
properties from work-hardening
- Good control of dimensional
tolerances
- Improved surface finish (no
oxide film)
- No heating required
- Competitive production rates
and costs
Extruded Metals
Typical extruded metals (hot or
cold)
Aluminum, copper, magnesium,
zinc, tin and alloys of these
Steel alloys are usually extruded
hot; softer steels may be
extruded cold
Others such as titanium and
refractory metals may be
extruded, but with difficulty
Extruded Metals
Extrusion Temperature Ranges
Lead 200-250 °C
Aluminum and its alloys 375-475 °C
Copper and its alloys 650-975 °C
Steels 875-1300 °C
Refractory alloys 975-2200 °C
Extrusion of Nonmetals
Materialsrubber
plastic
solvents
candy
glass
Productswindow seals
door seals
hose and tubing
wire insulation
candy canes
Hot Feed and Cold
Feed Extrusion
Heating/melting
Ribbon Pellets
Cold Feed Extrusion
Hot Feed Extrusion
Temperature zones
Wire, Tube, Bar, Rod
Drawing
Extrusion pushes the material
through the die; drawing pulls
the material through the die
Drawing
Products
electrical wire
cable
wire stock for fences, hangers,
shopping carts etc.
rod stock for nails, screws,
rivets, springs etc.
metal bars
Drawing Process
Advantages:
- Close dimensional control
- Good surface finish
- Improved strength and hardness
- Adaptability to mass production
Gold
Gold is the most ductile metal
that exists.
4 pounds of gold can be drawn
into a wire that stretches
across the country.
Summary
Extrusion and drawing provide
ways to form shapes with
uniform cross sections at high
production rates
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