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Rolling and Forging
Manufacturing
Processes
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Outline
Temperature
RollingFlat Rolling
Shape Rolling OperationsThread Rolling
Seamless Tubing and Pipe
Rolling Nonmetallic Materials
ForgingOpen-Die ForgingClosed-Die Forging
Roll Forging
Heading
Rotary SwagingForging Machines
Dies
Economics
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Rolling and Forging
Rolling
The thickness of a slab of a
slab or plate is reduced bycylindrical rolls which rotate topull the material between themand compress it
Forging
A workpiece is compressed
between opposing dies so thatthe material is forced into thedie shape
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Temperature in Metal
FormingCold working (room temperature
or slightly higher)
Warm working (30% - 50% of themelting temperature)
Hot working (50% - 75% of themelting temperature)
Isothermal formingTools are preheated to preventsurface cooling during forming
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Structure/Property
Modification
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Cold Working
Advantages
- No heating required
- Better surface finish- Better dimensional accuracy
- Parts are interchangeable
- Better strength, fatigue andwear properties
- Directional properties can beimparted
- Minimal contaminationproblems
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Cold Working
Disadvantages
- Higher forces required
- More powerful equipmentrequired
- Less ductility is available
- Surfaces must be clean- Intermediate anneals may be
needed to restore ductility
- Directional properties may be
detrimental- May produce undesirable
residual stresses
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Typical Rolled Products
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Typical Rolled Products
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Rolling Process
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Rolling Process
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Rolling Process
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Rolling Process
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Rolling Process
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Example of a Hot
Rolling Line
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Rolling Defects
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Shape Rolling
Uses a series of specially shaped
rolls to form a beam with a specific
cross section (such as an I-beam)
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Ring Rolling
Uses rolls to form a thick, small-
diameter ring into a thin, larger-
diameter ring
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Ring Rolling
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Thread Rolling
Uses moving dies with grooves to
form threads on cylindrical parts
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Thread Rolling
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Material Property
Changes
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Roll Piercing
Uses compressive stresses on a
cylindrical part to cause tensile
forces at the interior, creating ahole to form a thick-walled tube
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Example of a Tube
Rolling Mill
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Rolling Nonmetallic
Materials- Paper
- Plastic sheets
- Rubber products
- Reinforced fabric
Calendering
Passes material through a
series of gaps between rolls to
form a thin sheet
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Calendering
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Calendering
Example of a calendered rubber sheet with twolayers
Courtesy Cooper Tire
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Calendering of Rubber
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Coated Products
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Reinforced Materials
spools
reinforcing
material
windup
coating
material
Coating on both sides of
reinforcing material
comb
coating
material
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Reinforced Materials
Example of a polyester-reinforced rubber sheet withfibers exposed
Courtesy Cooper Tire
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Reinforced Materials
Example of a steel-belted rubber sheet with the beltexposed
Courtesy Cooper Tire
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Calender Control
Systems
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Calendering Thickness
Sensors
X rays or beta
radiation (electrons)
Detector
Emitter
some radiation is
blocked, depending
on thickness
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Milling
Squeezes material between rolls to
mix or preheat it for further
processes
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Forging
ForgingA deformation process in which
the material is compressed
between dies, using impact orgradual pressure to form the
part
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Forging
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Example of a Forging
Machine
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Example of a Forging
Machine
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Working Temperature
Hot Forging
Material is above its
recrystallization temperature
Cold Forging
Increased strength from strainhardening
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Forging
Billet
A piece of material with a square or circular cross
section; usually produced by a deformation process
such as rolling or extrusion
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Open Die Forging
Compresses the work between flat or
nearly flat dies
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Open Die Forging
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Open Die Forging
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Open Die Forging
Advantages
Simple, inexpensive dies; wide
range of sizes; good strength
Limitations
Simple shapes only; difficult tohold close tolerances;
machining necessary; low
production rate; poor utilizationof material; high skill required
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Closed Die Forging
Also called impression-die forging;
compresses the material into the
shape of the die cavity
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Closed Die Forging
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Closed Die Forging
Advantages
Good utilization of material;
better properties than open dieforging; good dimensional
accuracy; high production rate;
good reproducibility
Limitations
High die cost for smallquantities; machining often
necessary
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Roll Forging
Uses grooved rolls to reduce
thickness and increase length of
round or flat bars
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Roll Forging
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Roll Forging
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Roll Forging
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Coining
Uses dies to press fine detail into
both sides of the workpiece
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Upsetting/Heading
Decreases the length and increases
the diameter of the workpiece;
often used to form heads on nails,
bolts, etc.
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Orbital Forging
Uses a die that moves in various
directions to compress the
workpiece
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Swaging
Uses hammering dies to decrease
the diameter of the part
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Swaging
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Forging Dies and Die
InsertsSeparate inserts may be used for
forging complex shapes; this may
be less expensive than a complexsingle-piece die
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Forging Defects
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Forging Machines
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Forging Machines
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Example of a Forging
Machine
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Economics
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Summary
Rolling and forging shape parts
by deforming the material into
the desired shape
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