EMAE 160 Final Exam Questions and
Answers
Explain the term parting line when referencing the die casting process. - ANSWER-
The parting line is created when the two halves of the die meet. Flash occurs at the
parting line. The parting line often marks the border between the inside and outside
of the part
The "lost foam" or full-mold process requires what type of pattern? - ANSWER-
Evaporative-pattern casting, pattern made of polystyrene foam
Which of the following statements best describes the shell molding process? -
ANSWER-b) a casting process using metal masters and a resin to bind the molding
sand
The parting line in injection molding is which of the following? - ANSWER-c) The joint
between 2 mold halves
In terms of casting work, what is a runner? - ANSWER-Runners are connected
channels that convey the molten metal to different parts of the mold.
What type of mold is used in sandcasting? - ANSWER-Expendable sandmold
Which types of casting qualify as precision casting processes? - ANSWER-
Investment casting, plaster mold casting
In casting, what is a flask? - ANSWER-Type of tooling used to contain a mold. Only
has sides and no top or bottom, forms a frame around the mold
In sand casting, how does the volumetric size of the pattern compare to the finished
cast part? - ANSWER-Pattern must be larger than the finished cast part because of
thermal contraction and solidification shrinkage, this is called the shrinkage
allowance.
Describe shell molding. - ANSWER-Expendable mold casting process that uses
resin-covered sand to form a mold. First, a 2 piece metal pattern is clamped to a
dump box, which is then flipped, allowing the sand-resin mixture to coat the pattern
and form a shell. The pattern halves with the shells are cured in an oven and the
shell is ejected from the pattern. The 2 shells are clamped together to form a mold
and placed inside a flask filled with metal shot.
Name another term for investment casting and explain the origin - ANSWER-"Lost-
wax" casting; dates back to 3000s BC; used by Egyptians to make jewelry and
statuettes. Also used by the Mesopotamians, Greeks, Romans, and other to make
jewelry and small statues.
, List those metals that are typically die cast - ANSWER-Aluminum, magnesium, zinc,
lead, tin
In terms of die casting, what is flash? - ANSWER-Excess material attached to a cast
product caused by leakage of material beginning along parting line
What is the symbol for surface finish, and what parameters may be included? -
ANSWER-Surface finish is shown with a check and a number. That number is in
micro inches (μin)
What are ribs and gussets? - ANSWER-Ribs and gussets increase strength. Ribs
are a structure of side walls that are attached to the main wall to add strength and
rigidity to a primary wall. A gusset is a triangular shaped rib.
What is the significance of draft on a cast part? - ANSWER-It is the amount of taper
for molded or cast parts perpendicular to parting line; by tapering the sides of a mold
by an appropriate "draft angle", the mold will be easier to remove
How are internal features created in a sand casting? - ANSWER-Cores are
additional pieces that form the internal holes and passages of the casting. Cores are
typically made out of sand so that they can be shaken out of the casting, rather than
require the necessary geometry to slide out. As a result, sand cores allow for the
fabrication of many complex internal features.
What type of sand is most often used for sand casting? What type of sand is used for
core creation? - ANSWER-Sand casting: Green sand or Silica
Core creation: green sand cores or dry sand cores (silica sand)
What material is used to create the pattern in shell molding? Why? - ANSWER-Metal
(iron or steel normally). So the metal can be heated and will partially cure the sand to
make the mold.
In die casting, what is the ejection system and how does it operate? - ANSWER-
Ejector pins; attached to ejector half of casting in order to push out casting from mold
cavity
What materials may be used in Hot Chamber die casting? What about Cold
Chamber? - ANSWER-Hot chamber: zinc, tin, lead
Cold chamber: aluminum, magnesium, and copper
What is the function of a sprue and riser? - ANSWER-Sprue: a hole in the mold in
which liquid material enters the mold
Riser: a reservoir built into mold to prevent cavities due to shrinkage
What is the function of a runner and gate? - ANSWER-Runner: a channel for the
molten metal to get into the mold
Gate: places where liquid material enters the casting
What are the differences between Centrifugal Casting and Semi-Centrifugal? -
ANSWER-The manufacturing process of both metal casting techniques uses the
Answers
Explain the term parting line when referencing the die casting process. - ANSWER-
The parting line is created when the two halves of the die meet. Flash occurs at the
parting line. The parting line often marks the border between the inside and outside
of the part
The "lost foam" or full-mold process requires what type of pattern? - ANSWER-
Evaporative-pattern casting, pattern made of polystyrene foam
Which of the following statements best describes the shell molding process? -
ANSWER-b) a casting process using metal masters and a resin to bind the molding
sand
The parting line in injection molding is which of the following? - ANSWER-c) The joint
between 2 mold halves
In terms of casting work, what is a runner? - ANSWER-Runners are connected
channels that convey the molten metal to different parts of the mold.
What type of mold is used in sandcasting? - ANSWER-Expendable sandmold
Which types of casting qualify as precision casting processes? - ANSWER-
Investment casting, plaster mold casting
In casting, what is a flask? - ANSWER-Type of tooling used to contain a mold. Only
has sides and no top or bottom, forms a frame around the mold
In sand casting, how does the volumetric size of the pattern compare to the finished
cast part? - ANSWER-Pattern must be larger than the finished cast part because of
thermal contraction and solidification shrinkage, this is called the shrinkage
allowance.
Describe shell molding. - ANSWER-Expendable mold casting process that uses
resin-covered sand to form a mold. First, a 2 piece metal pattern is clamped to a
dump box, which is then flipped, allowing the sand-resin mixture to coat the pattern
and form a shell. The pattern halves with the shells are cured in an oven and the
shell is ejected from the pattern. The 2 shells are clamped together to form a mold
and placed inside a flask filled with metal shot.
Name another term for investment casting and explain the origin - ANSWER-"Lost-
wax" casting; dates back to 3000s BC; used by Egyptians to make jewelry and
statuettes. Also used by the Mesopotamians, Greeks, Romans, and other to make
jewelry and small statues.
, List those metals that are typically die cast - ANSWER-Aluminum, magnesium, zinc,
lead, tin
In terms of die casting, what is flash? - ANSWER-Excess material attached to a cast
product caused by leakage of material beginning along parting line
What is the symbol for surface finish, and what parameters may be included? -
ANSWER-Surface finish is shown with a check and a number. That number is in
micro inches (μin)
What are ribs and gussets? - ANSWER-Ribs and gussets increase strength. Ribs
are a structure of side walls that are attached to the main wall to add strength and
rigidity to a primary wall. A gusset is a triangular shaped rib.
What is the significance of draft on a cast part? - ANSWER-It is the amount of taper
for molded or cast parts perpendicular to parting line; by tapering the sides of a mold
by an appropriate "draft angle", the mold will be easier to remove
How are internal features created in a sand casting? - ANSWER-Cores are
additional pieces that form the internal holes and passages of the casting. Cores are
typically made out of sand so that they can be shaken out of the casting, rather than
require the necessary geometry to slide out. As a result, sand cores allow for the
fabrication of many complex internal features.
What type of sand is most often used for sand casting? What type of sand is used for
core creation? - ANSWER-Sand casting: Green sand or Silica
Core creation: green sand cores or dry sand cores (silica sand)
What material is used to create the pattern in shell molding? Why? - ANSWER-Metal
(iron or steel normally). So the metal can be heated and will partially cure the sand to
make the mold.
In die casting, what is the ejection system and how does it operate? - ANSWER-
Ejector pins; attached to ejector half of casting in order to push out casting from mold
cavity
What materials may be used in Hot Chamber die casting? What about Cold
Chamber? - ANSWER-Hot chamber: zinc, tin, lead
Cold chamber: aluminum, magnesium, and copper
What is the function of a sprue and riser? - ANSWER-Sprue: a hole in the mold in
which liquid material enters the mold
Riser: a reservoir built into mold to prevent cavities due to shrinkage
What is the function of a runner and gate? - ANSWER-Runner: a channel for the
molten metal to get into the mold
Gate: places where liquid material enters the casting
What are the differences between Centrifugal Casting and Semi-Centrifugal? -
ANSWER-The manufacturing process of both metal casting techniques uses the
