• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

Card Range To Study



Play button


Play button




Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

70 Cards in this Set

  • Front
  • Back
categories of casting processes
1. expendable molds
2. permanent molds
3. composite molds
expendable molds
sand, plaster, mold is made from pattern, mold is expendable, pattern is either expendable or reusable
permanent molds
made of metals that maintain strength at high temps, metal conducts heat which can impact the microstructure and grain size
composite molds
made of 2 or more materials,
ex: sand, graphite, metal,
have permanent and expendable portions
sand casting
most prevalent way of casting metals
sand casting process
a. placing a pattern in sand to make an imprint
b. incorporating a gating system
c. removing the pattern and filling the mold cavity with molten metal
d. allowing the metal to cool
e. breaking away the mold
f. removing the casting
types of sand
naturally bonded, synthetic
naturally bonded
bank sand
lake sand, preferred
factors important in selection of sand for molds
fine grain enhances mold strength but lowers permeability (where fluids and gases penetrate through pores), good collapsibility
good collapsibility allows casting to shrink while cooling to avoid defects in the casting (hot tearing, cracking)
types of sand molds
green-sand, cold-box, no-bake
green molding sand
mix of sand, clay, water,
cheapest and most common,
sand can be recycled
skin-dried [method]
mold surfaces are dried, by storing the mold in air or by drying it with torches,
for large castings
cold-box mold
binder are blended into sand to bond the grains chemically and make stronger,
more expensive, more dimensionally accurate
no-bake mold
synthetic liquid resin is mixed with sand and mixture harden at room temp
cold-setting processes
no-bake, cold-box
called because they bond without heat
major features of sand molds
1. flask
2. pouring basin
3. sprue
4. runner system, gates
5. risers
6. cores
7. vents
supports mold, 2 piece molds have cope on top and drag on bottom
parting line
separates cope and drag
through which molten metal flows downward
runner system
has channels which carry molten metal from sprue to mold cavity
inlets into mold cavity
-supply molten metal to the casting as it shrinks during solidification
-types: blind riser, open riser
inserts made of sand and placed in the mold to form hollow regions or otherwise define the interior surface of the casting, used on outside to form lettering or deep external pockets
placed in molds to carry off gases produced when molten metal comes into contact with the sand in the mold and core, also exhaust air from mold cavity as molten metal flows into the mold
used to mold the sand mixture into the shape of the casting
wood, plastic, metal
parting agent
coating on patterns to facilitate removal of casting from molds
one-piece patterns
for simple shapes, low-quantity production,
wood, inexpensive
split patterns
two-piece patterns, each part forms a portion of the cavity, for complicated shapes
match-plate patterns
common type of mounted pattern in which two-piece patterns are constructed by securing each half of one or more split patterns to the opposite sides of a single plate
core prints
recesses added to the pattern to locate and support the core and provide vents for gases to escape
metal supports, used to anchor the core in place
vertical flaskless molding
a. halves of pattern form vertical chamber wall against which sand is blown and compacted
b. mold halves are packed horizontally, with parting line oriented vertically, and moved along a pouring conveyer
fill flask uniformly with sand under high-pressure stream, used to fill large flasks, operated by machine
impact molding
sand is compacted by a controlled explosion or instantaneous release of compressed gases, method produces molds with uniform strength and good permeability
vacuum molding
V process, for high surface detail, large, flat, castings
1. pattern is covered tightly with a thin sheet of plastic
2. flask is placed over the coated pattern and is filled with dry, binderless sand
3. a second sheet of plastic then is placed on top of the sand
4. a vacuum action compacts the sand
5. take away the pattern
6. both halves are assembled
7. when the metal has solidified, the vacuum is turned off and the sand falls away, releasing the casting
shell molding
for small mechanical parts requiring high precision
precision casting
consists of shell molding, ceramic-mold and investment casting
plaster molding
mold is made of plaster of paris mixed with water then poured over the pattern and allowed to set
antioch process
molds are dehydrated in an autoclave then rehydrated in air, increases permeability
ceramic-mold casting
similar to plaster-mold process except uses refractory mold materials suitable for high-temp applications
shaw process
ceramic facings are backed by fireclay to give strength to the mold
evaporative-pattern casting
uses polystyrene pattern which evaporates upon contact with molten metal to form a cavity for the casting
advantages of evaporative-pattern casting
simple, inexpensive, capable of producing complex shapes, minimal finishing operations required, can be automated
investment casting
lost-wax process, produces office equipment
1. inject wax or plastic pattern
2. eject pattern
3. pattern assembly (tree)
4. slurry coating
5. stucco coating
6. completed mold
7. pattern melt-out
8. pouring
9. shakeout
10. pattern
where does the term "investment" derive from?
that fact that the pattern is invested (surrounded) with the refractory material
semipermanent-mold casting
uses easily collapsable sand cores that allow you to have intricate internal cavities
slush casting
makes hollow castings with thin walls, uses principle that a solidified skin develops in a casting and becomes thicker with time
pressure casting
molten metal is forced upward by gas pressure into a graphite to metal mold
die casting
molten metal is forced into the die cavity at pressures ranging from .7 to 700 MPa
types of die casting machines
cold-chamber, hot-chamber
hot-chamber process
uses piston which forces certain volume of metal into the die cavity through a gooseneck and nozzle
cold-chamber process
molten metal is poured into the injection cylinder at room temp, then the metal is forced into the die cavity at pressures from 20 to 70 MPa
insert molding
process of die casting pins and shaft integrally, like placing wooden sticks in popsicle prior to freezing
heat checking
surface cracking from repeated heating and cooling of the die
semicentrifugal casting
used to cast parts with rotational symmetry
mold cavities of any shape are placed a certain dist from the axis of rotation, molten metal is poured from the center and forced into the mold by centrifugal forces
which 2 casting processes incorporate both casting and forging?
squeeze casting, semisolid-metal forming
liquid-metal forming, involves solidification of molten metal under high pressure, uses die, punch, ejector pin
semi-solid metal forming
metal (consisting of liquid and solid) is stirred so that all of the dendrites are crushed into fine solids
means viscosity decreases when agitated
crystal-pulling method (Czochralski process)
a seed crystal is dipped into molten metal and pulled out slowly while being rotated
floating-zone method
induction coil heats polycrystalline silicon resting on a crystal while moving upward
amorphous alloys
metallic glasses
melt spinning
alloy is melted by induction in a ceramic crucible, then propelled under high gas pressure against a rotating copper disk, which chills the alloy rapidly
splat cooling
rapid chilling
chill block
rotating copper block
melting furnaces
electric-arc, induction, crucible, cupolas, levitation melting
where casting operations are carried out