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Flashcards in Chapter 6 Deck (30):

Adv and disadv of expendable

More complex shapes.
Production rates limited since longer to make mold than the casting itself


Adv and Disadv of permanent

Higher production rate
Geometries limited by need to open mold


Pattern materials (3)

Wood, metal, and plastic


Pattern types (4)

Solid pattern
Split pattern
Match-plate pattern
Cope and drag pattern


Definition of chaplets

Hold cores in place during pouring


Silica SiO2 properties for small, large, and irregular

Good refractory properties
Small grain size for better surface finish
Large grain is more permeable allowing gases to escape during pouring
Irregular grain strengthen molds due to interlocking but reduces permeability


Typical mix

90% sand, 3% water, and 7% clay


Types of Sand Mold (3)

Green-sand - Mixture that has moisture
Dry-sand - Organic binders instead of clay
Skin-dried - Drying green-sand to a depth of 10 -25 mm using torches or heating lamps


Shell molding and Adv3/Disadv1

Heated pattern covered in thermosetting resin. Then heated. Then used to be a mold.
Better surface finish
Good dimensional accuracy
Mass production


Expanded Polystyrene Process and Adv2/Dadv2

Lost pattern so foam pattern coated with refractory compound. Poured into it.

No need to remove pattern
Speeds mold-making because no need for two halves.

New pattern needed every time.
Cost of producing patterns makes it expensive or not


Investment Casting and Adv(4)/Disa(2)

Lost wax process
Make wax pattern. Cover in refractory coat. Melt wax away leaving shell. Pour.

Very complex parts made
Very accurate
Wax reused
Net shape process

Requires many steps


Explain Sand casting

Pattern made. Pack sand around it. Then separate sand into two parts. Pour then break sand off.


Plaster mold casting
Adv(2) Disa(3)

Similar to sand casting but made of plaster. Mixture of plaster and water flows around pattern improving details and surface finish.

Good accuracy and surf finish
Capable of thin cross sections

Must bake to remove moisture
Mold strength lost if over bake
Limited to low melt. point alloys


Ceramic Mold Casting

Similar to plaster and sand but refractory ceramic higher temp.
Too similar . Just does high temp alloys.


Permanent Mold material for low melting point alloys and for steel

Lower melting point - Steel and cast iron

Steel - refractory material


Adv (2) and Disadv (3) for Permanent Mold Casting

Good dimensional accuracy and surface finish.
Rapid solidification. Casts stronger.

Lower melting point.
Simpler geometries
High cost of mold


Die casting and material type

Adv (4) and Disadv(2)

Molten metal injected into cavity. Pressure maintained.
Tool steel, mold steel

Cheap for large prod
Good accuracy and surf finish
Thin section possible
Rapid cooling so small grain size and good strength

Limited to low melt temp
Part must be able to be removed


Hot Chamber Die casting and its metals (4)

Already set to inject.

Low melting point metals
Zinc, tin, lead and magnesium
High production rate


Cold-chamber Die casting and its metals (3)

Poured and then injected.

High production but slower than hot chamber
Aluminum, brass, and Magnesium alloys


Centrifugal Casting

Rotated. Circular centers.


Cupolas Furnace

Vertical and cylindrical
For melting cast irons.


Crucible Furnace
Material Made of
Material it melts

Indirect fuel fired furnace.
High temp steel alloy or refractory material
For bronze, brass, and zinc/aluminum alloys


Name the three crucible furnaces

lift-out crucible
stationary pot (ladle)
tilting-pot furnace


What furnace for melting steel

Electric-arc furnace.
high power consumption. High melting capacity


Induction Furnaces
Metals for (3)

AC induces magnetic field in metal. Rapid heating and melting.
No contact then high quality and purity
Steel, cast iron, and aluminum


Most important casting alloy and types of it. Pouring temp

Cast iron
Grey cast iron, nodular iron, white cast iron, malleable iron and alloy cast irons
1400 C


Aluminum prop (4)

Low pouring temp
light weight
easy to machine
very castable


Copper Alloy Pro (3)

Corrosion resistance
attractive appearance
Good bearing qualities


Zinc Alloys (4)

Low pouring temp
Good fluidity
Low creep strength


Draft guidelines

Facilitates removal of pattern or the part from the mold