CASTING
Casting process: Introduction of molten metal into a mold cavity
; upon solidification, metal takes the shape of the
cavity.Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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CASTIAl ost all etals can be cast the ( or nearly in) the final
shape desired, only inor finishing required. With appropriate
control of aterial and process para eters, parts can be cast with
unifor properties throughout. Intricate shapes Internal cavities,
hollow parts Very large/very s allEngine blocks Cylinder heads
Trans ission housings Pistons Turbine disks Railroad and auto otive
wheels Orna ental artifactsManufacturing Processes for Engineering
Materials, 5th ed. Kalpakjian Schmid 2008, Pearson Education ISBN
No. 0-13-227271-7
Temperature & Density for Castings
FIGURE 5.1 (a) Temperature as a function of time for the
solidification of pure metals. Note that freezing takes place at a
constant temperature. (b) Density as a function of
time.Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Two-Phased Alloys
FIGURE 5.2 (a) Schematic illustration of grains, grain
boundaries, and particles dispersed throughout the structure of a
two-phase system, such as lead-copper alloy. The grains represent
lead in solid solution of copper, and the particles are lead as a
second phase. (b) Schematic illustration of a two-phase system,
consisting of two sets of grains: dark and light. Dark and light
grains have their own compositions and properties.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Phase Diagram for Nickel-Copper
FIGURE 5.3 Phase diagram for nickel-copper alloy system obtained
by a low rate of solidification. Note that pure nickel and pure
copper each have one freezing or melting temperature. The top
circle on the right depicts the nucleation of crystals; the second
circle shows the formation of dendrites; and the bottom circle
shows the solidified alloy with grain boundaries.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Iron-Iron Carbide Phase Diagram
FIGURE 5.4 (a) The iron-iron carbide phase diagram. (b) Detailed
view of the microstructures above and below the eutectoid
temperature of 727C (1341F). Because of the importance of steel as
an engineering material, this diagram is one of the most important
phase diagrams.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Texture in Castings
FIGURE 5.5 Schematic illustration of three cast structures of
metals solidified in a square mold: (a) pure metals, with preferred
texture at the cool mold wall. Note in the middle of the figure
that only favorable oriented grains grow away from the mold
surface; (b) solid-solution alloys; and (c) structure obtained by
heterogeneous nucleation of grains(Inoculation-TiB2, AlSi).
Manufacturing Processes for Engineering Materials, 5th ed.
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Alloy Solidification & Temperature
FIGURE 5.6 Schematic illustration of alloy solidification and
temperature distribution in the solidifying metal. Note the
formation of dendrites in the semi-solid (mushy) zone.Manufacturing
Processes for Engineering Materials, 5th ed. Kalpakjian Schmid
2008, Pearson Education ISBN No. 0-13-227271-7
Solidification Patterns for Gray Cast Iron
FIGURE 5.7 Schematic illustration of three basic types of cast
structures: (a) columnar dendritic; (b) equiaxed dendritic; and (c)
equiaxed nondendritic. Source: After D. Apelian.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Cast StructuresFIGURE 5.8 Schematic illustration of three basic
types of cast structures: (a) columnar dendritic; (b) equiaxed
dendritic; and (c) equiaxed nondendritic(rheocasting).
FIGURE 5.9 Schematic illustration of cast structures in (a)
plane front, single phase, and (b) plane front, two phase. Source:
After D. Apelian.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Mold Features
FIGURE 5.10 Schematic illustration of a typical sand mold
showing various features.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Temperature Distribution
FIGURE 5.11 Temperature distribution at the mold wall and
liquid-metal interface during solidification of metals in
casting.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Skin on Casting
Chvorinovs Rule:
FIGURE 5.12 Solidified skin on a steel casting; the remaining
molten metal is poured out at the times indicated in the figure.
Hollow ornamental and decorative objects are made by a process
called slush casting, which is based on this principle. Source:
After H.F. Taylor, J. Wulff, and M.C. Flemings.
Manufacturing Processes for Engineering Materials, 5th ed.
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Manufacturing Processes for Engineering Materials, 5th ed.
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Defects in castingPorosity due to gases smooth bubbles Gases
have much greater solubility in liquid metals than in solids. hen a
metal begins solidify, the dissolved gases are expelled from the
solution. Precautions: Flushing or purging ith inert gas Adding
deoxidizers Pour in vacuum condition due to shrinkage rough voids
Use internal/external chills
Impurities oxidesreaction of the molten metal ith environment
spalling of the mold and core surface Precautions: Filtered out
during processing of molten metal
Manufacturing Processes for Engineering Materials, 5th ed.
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Shrinkage
TABLE 5.1 Volumetric solidification expansion for various cast
metals.
contraction or
Manufacturing Processes for Engineering Materials, 5th ed.
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Chills
FIGURE 5.35 Various types of (a) internal and (b) external
chills (dark areas at corners), used in castings to eliminate
porosity caused by shrinkage. Chills are placed in regions where
there is a larger volume of metal, as shown in (c).Manufacturing
Processes for Engineering Materials, 5th ed. Kalpakjian Schmid
2008, Pearson Education ISBN No. 0-13-227271-7
Elimination of Porosity in Castings
FIGURE 5.37 (a) Suggested design modifications to avoid defects
in castings. Note that sharp corners are avoided to reduce stress
concentrations; (b, c, d) examples of designs showing the
importance of maintaining uniform cross-sections in castings to
avoid hot spots and shrinkage cavities.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Cold ShutInterface in a casting that lacks complete fusion
because of the meeting of two streams of partially solidified metal
Insufficient quantity of liquid metal in the ladle; remature
interruption of pouring due to workmans error
Hot Tearing Occurs due when casting is not allowed to shrink
freely
Misrunincomplete filling of the mold due to low pouring
temperature
FlashLeak metal forms when the cope and drag do not match
Manufacturing Processes for Engineering Materials, 5th ed.
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Defective surfaceSurface folds, laps, scars, adhering sand
layers, oxide scales
Manufacturing Processes for Engineering Materials, 5th ed.
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Design Modifications
FIGURE 5.38 Suggested design modifications to avoid defects in
castings. Source: Courtesy of The North American Die Casting
Association.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Cast Material Properties
FIGURE 5.13 Mechanical properties for various groups of cast
alloys. Compare with various tables of properties in Chapter 3.
Source: Courtesy of Steel Founders' Society of America.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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General Characteristics of Casting
TABLE 5.2 General characteristics of casting
processes.Manufacturing Processes for Engineering Materials, 5th
ed. Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Typical Applications & Characteristics
TABLE 5.3 characteristics.
Typical
applications
for
castings
and
casting
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
0-13-227271-7
Properties & Applications of Cast Iron
TABLE 5.4 irons.
Properties and typical applications of cast
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Nonferrous Alloys
TABLE 5.5 Typical properties of nonferrous casting alloys.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Microstructure for Cast Irons
FIGURE 5.14 Microstructure for cast irons. (a) ferritic gray
iron with graphite flakes; (b) ferritic nodular iron, (ductile
iron) with graphite in nodular form; and (c) ferritic malleable
iron. This cast iron solidified as white cast iron, with the carbon
present as cementite (Fe3C), and was heat treated to graphitize the
carbon.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Product on of Iron and St
l
Iron Ore
Limestone
Coke
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Melting Processes
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Melting Practice and Furnaces
Need major investment Fuel: Gas, fuel oil, fossil fuel High
production rate Operate continuously Less pollution Good for
ferrous High melting rates Good for large charge ~2000 C melting
temp. Humidity problem! Composition controlled ~3000 C melting
temp. Good for small amount of casting Composition controlled
Electromagnetic stirring adv esp. for alloying purpose Levitation
melting No need crucible no contamination (oxide, inclusion)
Uniform fine grained structure Manufacturing Processes for
Engineering Materials, 5th ed. Kalpakjian Schmid No gas porosity
2008, Pearson Education ISBN No. 0-13-227271-7
INGO CastinThe first step in metal processing is the shaping of
the molten metal into a ingot for further processings.
Killed Steel (Al+Si)Fully deoxidized steel Chemical and
mechanical properties are uniform No porosity iping
problem-Scrap!!
Semi-killed Steel(Al)Some porosity ittle pipe-less scrap ess
cost
Rimmed SteelNo piping Gasses form blo holes close to outer rim
of the ingotManufacturing Processes for Engineering Materials, 5th
ed. Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Casting Processes Comparison
T BLE 5.8 Casting Processes, and their dvantages and
Limitations.Manufacturing Processes for Engineering Materials, 5th
ed. Kalpakjian Schmid 2008, Pearson Education ISBN No.
0-13-227271-7
Continuous-Casting Molten metal travels through water-cooled
copper moldsBegin to solidify as it travels downward along a path
supported by rollers No piping and micro structural /mechanical
variations More efficient, higher productivity Less cost
Maybe cut into desired lengths by shearing Or it may be fed
directly in to a rolling mills (I-beam) Cleaning/Pickling by
chemicals to remove surface oxides Cold rolling to improve surface
finish/strength Coating to reduce corrosion (galvanizing)
Manufacturing Processes for Engineering Materials, 5th ed.
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Sand Casting
FIGURE 5.16 Schematic illustration of the sequence of operations
in sand casting. (a) A mechanical drawing of the part, used to
create patterns. (b-c) Patterns mounted on plates equipped with
pins for alignment. Note the presence of core prints designed to
hold the core in place. (d-e) Core boxes produce core halves, which
are pasted together. The cores will be used to produce the hollow
area of the part shown in (a). (f) The cope half of the mold is
assembled by securing the cope pattern plate to the flask with
aligning pins, and attaching inserts to form the sprue and risers.
(g) The flask is rammed with sand and the plate and inserts are
removed. (h) The drag half is produced in a similar manner. (j) The
core is set in place within the drag cavity. (k) The mold is closed
by placing the cope on top of the drag and securing the assembly
with pins. (l) After the metal solidifies, the casting is removed
from the mold. (m) The sprue and risers are cut off and recycled,
and the casting is cleaned, inspected, and heat treated (when
necessary). Source: Courtesy of Steel Founders' Society of
America.Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
0-13-227271-7
Sands-SiO2:
Sand characteristics
Refractoriness- Ability to withstand high temperatures
Cohesiveness- Ability to retain given shape Permeability- Ability
to allow gasses to escape Collapsibility-Ability to allow metal to
shrink and free the casting
Fine grain Better mold strength Better surface finish Coarse
grain Better permeabilityManufacturing Processes for Engineering
Materials, 5th ed. Kalpakjian Schmid 2008, Pearson Education ISBN
No. 0-13-227271-7
Types of patterns
One piece, split, match plate, and loose piece Materials
Wood-inexpensive Metal Plastics Laminated Object Mfg.(LOM)/
Stereolithography (SLA)
Strength and durability depends on number of castings Coated
with parting agent to help removal
Core: used for casting with internal cavities
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Sand Mold Types:
Green molding: Sand+Clay+Water Least expensive method Skin Dried
Method: Drying skin with torches Good for large casting to obtain
higher mold strength Better surface finish -Higher mold distortion
-susceptible to hot tearing due to lower collapsibility -production
rate slower due to the drying time
Cold-Box Method: Sand+Organic Binder Better dimensional accuracy
-expensive
Manufacturing Processes for Engineering Materials, 5th ed.
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Expendable Molding ProcessSand Casting Steps1 SAND COMPACTING :
Compact the sand by hand hammering or ramming it around the parting
agent coated pattern
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Sand casting example : Fence Spear
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Match-plate pattern
Filling mold flask with green sand before ramming
Manufacturing Processes for Engineering Materials, 5th ed.
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2 CORE PLACEMENT: Cores have been placed in position
3 - WEIGHTED DOWN: The two halves of mold are closed, clamped,
weighted -to prevent the separation of the mold sections under the
pressure exerted when the molten metal is poured into the mold
cavityFlashed part due to separated mold sections
Manufacturing Processes for Engineering Materials, 5th ed.
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Completed drag half of mold in flask
Completed cope half of mold in flask.
Manufacturing Processes for Engineering Materials, 5th ed.
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Sand impression in cope half of mold for spear casting.
Completed green sand mold in snap flask.
Completed green sand mold with flask removed. Finished cast iron
spear reproduction
Manufacturing Processes for Engineering Materials, 5th ed.
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4 - POURING:
Deliver the molten metal into mold cavity 5 FINISHING
PROCESS:
After solidification, casting is shaken out of its mold Sand and
oxide layers adhering to the casting are removed by vibration
(shaker) or by sand blasting
-Risers and gates are cut-off by oxy fuel-gas cutting, sawing,
shearing and abrasive wheelsManufacturing Processes for Engineering
Materials, 5th ed. Kalpakjian Schmid 2008, Pearson Education ISBN
No. 0-13-227271-7
Sand Casting Advantages & Disadvantages
Advantages
Disadvantages
General tooling costs are low Sand in most cases can be reused
in some form Can handle a wide variety of metals Relatively easy
process to obtain net shape or near-net shape
Part tolerances +/- 2-3 mm Poor surface finish Limited design
freedom In hand ramming, process can be labor intensive Single use
of mold
Cast iron engine blocks
Very large propellers for ocean liners
Manufacturing Processes for Engineering Materials, 5th ed.
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Shell-Molding ProcessPattern: Metal (Ferrous/Aluminum) : heated
~250 C : coated with parting agent Mixture: Sand+2-4% Thermosetting
Resin Binder
Gear housings Cylinder heads Connecting rods
+Small parts with good dimensional5th ed. Manufacturing
Processes for Engineering Materials, Kalpakjian Schmid accuracy
2008, Pearson Education and surface finish; ISBN No. 0-13-227271-7
+High production rate
-Part size limited; -Expensive patterns and equipment
required.
Plaster MoldingMg / Al / Zinc / Cu Similar to sand casting
except mold is made of plaster of Paris (gypsum Talc-Silica Flour)
Plaster and water mixture is poured over plastic or metal pattern
to make a mold
Disadvantages: Advantages: +Good dimensional accuracy, surface
finish +Capability to make intricate shapes, thin Manufacturing
Processes for Engineering Materials, 5th ed. cross-sections in
casting Kalpakjian Schmid 2008, Pearson Education ISBN No.
0-13-227271-7
- Moisture in plaster mold causes problems: - Mold must be baked
to remove moisture - Plaster molds cannot stand high temperatures
(Max 1200C) - Mold making time relatively long (16 hours
preheat).
Ceramic Mold ManufactureSlurry: Fine Grained Zircon- Aluminum
Oxide-Silicon Oxide-Bonding Agent
FIGURE 5.18 Sequence of operations in making a ceramic mold.
Ferrous and other high temp. Alloys, Stainless Steel , Tool
Steel Impellers, cutters for machining, dies for metal working.
~700 kg. +IntricateManufacturing Processes for Engineering
Materials, 5th ed. shapes, Kalpakjian Schmid +Close tolerance
parts, 2008, Pearson Education ISBN No. 0-13-227271-7 +Good surface
finish. -Limited size.
Vacuum-Casting Process
Mixture: Fine Sand+Urethane +Amine Vapor (for curing)
FIGURE 5.19 Schematic illustration of the vacuum-casting
process. Note that the mold has a bottom gate. (a) before and (b)
after immersion of the mold into the molten metal. Source: After R.
Blackburn.
Mold held with a robot arm
artially immersed into molten metal Metal beginds to solidify
within a fraction of a second
Thin walled(0.75 mm) complex shapes with uniform properties l Zr
Ti Hf Low and high alloy steels andEngineering Materials, 5th ed.
Manufacturing Processes for stainless steel Superalloys for gas
turbinesKalpakjian Schmid 2008, Pearson Education ISBN No.
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Evaporative Pattern CastingSteps Raw S beads are placed in a
preheated l die S expands and takes the shape of die cavity Die is
then cooled and opened, S pattern removed attern is then coated
with a refractory slurry Coated pattern is dried and placed in a
flask Flask is filled with loose fine sand to support pattern Sand
is compacted Without removing the S pattern, molten metal is poured
into the mold, S pattern is vaporized immediately and fills the
cavity completely replacing the space previously occupied by the S
patternManufacturing Processes for Engineering Materials, 5th ed.
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Cylinder heads, crank shafts, brake components, manifolds,
machine bases
Investment Casting
FIGURE 5.21 Schematic illustration of investment casting (lost
wax process). Castings by this method can be made with very fine
detail and from a variety of metals. Source: Steel Founders'
Society of America.
Intricate shapes; excellent surface finish Manufacturing
Processes for Engineering Materials, 5th ed. and accuracy; almost
any metal cast. Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Part size limited; expensive patterns, molds, and labor.
Lost-Foam Casting of Engine Blocks
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Rotor Microstructure
FIGURE 5.22 Microstructure of a rotor that has been investment
cast (top) and conventionally cast (bottom). Source: Advanced
Materials and Processes, October 1990, p. 25. ASM
International.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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PERMANENT MOLD CASTING-Usually metal molds -Machined -Refractory
slurry coating -Water cooling -Mostly automated and high volume
production engine parts, kitchenware, gears etc. Semipermanent mold
casting: sand cores
Manufacturing Processes for Engineering Materials, 5th ed.
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Advantages:
+ Economical for large production quantities + Good dimensional
accuracy and surface finish + Thin sections are possible + Rapid
cooling provides small grain size and good strength to casting +
Low porosity; high production rate.
Disadvantages:
Generally limited to metals with low metal points Part geometry
must allow removal from die cavity
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Pressure & Hot-Chamber Die Casting
FIGURE 5.23 The pressure casting process, utilizing graphite
molds for the production of steel railroad wheels. Source: Griffin
Wheel Division of Amsted Industries Incorporated.
FIGURE 5.24 Schematic illustration of the hotchamber die-casting
process.
Manufacturing Processes for Engineering Materials, 5th ed.
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Cold-Chamber Die Casting
FIGURE 5.25 Schematic illustration of the coldchamber
die-casting process. These machines are large compared to the size
of the casting, because high forces are required to keep the two
halves of the die closed under pressure.
Manufacturing Processes for Engineering Materials, 5th ed.
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Properties of Die-Casting Alloys
TABLE 5.6 Properties and typical applications of common
die-casting alloys.Manufacturing Processes for Engineering
Materials, 5th ed. Kalpakjian Schmid 2008, Pearson Education ISBN
No. 0-13-227271-7
Centrifugal Casting
FIGURE 5.26 Schematic illustration of the centrifugal casting
process. Pipes, cylinder liners, and similarly shaped hollow parts
can be cast by this process.
Large cylindrical parts with good quality; high production
rate.Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Equipment is expensive; part shape limited.
Semicentrifugal Casting
FIGURE 5.27 (a) Schematic illustration of the semicentrifugal
casting process. Wheels with spokes can be cast by this process.
(b) Schematic illustration of casting by centrifuging. The molds
are placed at the periphery of the machine, and the molten metal is
forced into the molds by centrifugal forces.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Squeeze-Casting
FIGURE 5.28 Sequence of operations in the squeeze-casting
process. This process combines the advantages of casting and
forging.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Turbine Blade Casting
FIGURE 5.29 Methods of casting turbine blades: (a) directional
solidification; (b) method to produce a single-crystal blade; and
(c) a single-crystal blade with the constriction portion still
attached. Source: (a) and (b) After B.H. Kear, (c) Courtesy of ASM
International.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Crystal Growing
FIGURE 5.30 Two methods of crystal growing: (a) crystal pulling
(Czochralski process) and (b) floatingzone method. Crystal growing
is especially important in the semiconductor industry. (c) A
single-crystal silicon ingot produced by the Czochralski process.
Source: Courtesy of Intel Corp.
Manufacturing Processes for Engineering Materials, 5th ed.
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Melt-Spinning Process
FIGURE 5.31 (a) Schematic illustration of the melt-spinning
process to produce thin strips of amorphous metal. (b) Photograph
of nickel-alloy production through melt-spinning. Source: Courtesy
of Siemens AG.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Austenite-Pearlite Transformation
FIGURE 5.32 (a) Austenite to pearlite transformation of
iron-carbon alloys as a function of time and temperature. (b)
Isothermal transformation diagram obtained from (a) for a
transformation temperature of 675C (1247F). (c) Microstructures
obtained for a eutectoid iron-carbon alloy as a function of cooling
rate. Source: Courtest of ASM International.
Manufacturing Processes for Engineering Materials, 5th ed.
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Phase Diagram for Aluminum-Copper
FIGURE 5.33 (a) Phase diagram for the aluminum-copper alloy
system. (b) Various microstructures obtained during the
age-hardening process.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Outline of Heat Treating
TABLE 5.7 Outline of heat treatment processes for surface
hardening.Manufacturing Processes for Engineering Materials, 5th
ed. Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Heat Treatment Temperature Ranges
FIGURE 5.34 Temperature ranges for heat treating plain-carbon
steels, as indicated on the iron-iron carbide phase diagram.
Manufacturing Processes for Engineering Materials, 5th ed.
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Casting Processes Comparison
TABLE 5.8 Casting Processes, and their Advantages and
Limitations.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Hydrogen Solubility in Aluminum
FIGURE 5.36 Solubility of hydrogen in aluminum. Note the sharp
decrease in solubility as the molten metal begins to solidify.
Manufacturing Processes for Engineering Materials, 5th ed.
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Economics of Casting
FIGURE 5.39 Economic comparison of making a part by two
different casting processes. Note that because of the high cost of
equipment, die casting is economical mainly for large production
runs. Source: The North American Die Casting Association.
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian Schmid 2008, Pearson Education ISBN No.
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Lost-Foam Casting of Engine Blocks
FIGURE 5.40 (a) An engine block for a 60-hp 3-cylinder marine
engine, produced by the lost-foam casting process; (b) a robot
pouring molten aluminum into a flask containing a polystyrene
pattern. In the pressurized lost-foam process, the flask is then
pressurized to 150 psi (1000 kPa). Source: Courtesy of Mercury
Marine
Manufacturing Processes for Engineering Materials, 5th ed.
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