ME 383 Exam 1 Question and answers
correctly solved 2025/2026
Expendable Mold Processes - correct answer ✔mold is sacrificed to remove part
Advantage: more complex shapes possible
Disadvantage: production rates often limited by time to make mold
Permanent Mold Processes - correct answer ✔mold is made of metal and can be used to make many
castings
Advantage: higher production rates
Disadvantage: geometries limited by need to open mold
Sand Casting - correct answer ✔-Most widely used casting process
-The cavity in the sand mold is formed by packing sand around a pattern, then separating the mold into
two halves and removing the pattern
-If casting is to have internal surfaces, a core must be included in mold
-A new sand mold must be made for each part produced
Steps in Sand Casting - correct answer ✔1. Pour the molten metal into sand mold
2. Allow time for metal to solidify
3. Break up the mold to remove casting
4. Clean and inspect casting
-Separate gating and riser system
5. Heat treatment of casting is sometimes required to improve metallurgical properties
Desirable Mold Properties - correct answer ✔-Strength
, -Permeability
-Thermal stability ‐ to resist cracking on contact with molten metal
-Collapsibility
-Reusability ‐ Most sand cannot be reused from a broke mold
Other Expendable Mold Processes - correct answer ✔-Shell Molding
-Vacuum Molding
-Expanded Polystyrene Process
-Investment Casting
-Plaster Mold and Ceramic Mold Casting
Shell Molding - correct answer ✔Casting process in which the mold is a thin shell of sand held together
by thermosetting resin binder
Shell Molding Steps - correct answer ✔(1) A metal pattern is heated and placed over a box containing
sand mixed with thermosetting resin
(2) Box is inverted so that sand and resin fall onto the hot pattern, causing a layer of the mixture to
partially cure on the surface to form a hard shell
(3) Box is repositioned so loose uncured particles drop away
(4) Sand shell is heated in oven for several minutes to complete curing.
(5) shell mold is stripped from pattern.
(6) Two halves of the shell mold are assembled, supported by sand or metal shot in a box, and pouring is
accomplished.
(7) Finished casting with sprue removed
Shell Molding: Advantages and Disadvantages - correct answer ✔-Advantages:
-Smoother cavity surface permits easier flow of molten metal and better surface finish
correctly solved 2025/2026
Expendable Mold Processes - correct answer ✔mold is sacrificed to remove part
Advantage: more complex shapes possible
Disadvantage: production rates often limited by time to make mold
Permanent Mold Processes - correct answer ✔mold is made of metal and can be used to make many
castings
Advantage: higher production rates
Disadvantage: geometries limited by need to open mold
Sand Casting - correct answer ✔-Most widely used casting process
-The cavity in the sand mold is formed by packing sand around a pattern, then separating the mold into
two halves and removing the pattern
-If casting is to have internal surfaces, a core must be included in mold
-A new sand mold must be made for each part produced
Steps in Sand Casting - correct answer ✔1. Pour the molten metal into sand mold
2. Allow time for metal to solidify
3. Break up the mold to remove casting
4. Clean and inspect casting
-Separate gating and riser system
5. Heat treatment of casting is sometimes required to improve metallurgical properties
Desirable Mold Properties - correct answer ✔-Strength
, -Permeability
-Thermal stability ‐ to resist cracking on contact with molten metal
-Collapsibility
-Reusability ‐ Most sand cannot be reused from a broke mold
Other Expendable Mold Processes - correct answer ✔-Shell Molding
-Vacuum Molding
-Expanded Polystyrene Process
-Investment Casting
-Plaster Mold and Ceramic Mold Casting
Shell Molding - correct answer ✔Casting process in which the mold is a thin shell of sand held together
by thermosetting resin binder
Shell Molding Steps - correct answer ✔(1) A metal pattern is heated and placed over a box containing
sand mixed with thermosetting resin
(2) Box is inverted so that sand and resin fall onto the hot pattern, causing a layer of the mixture to
partially cure on the surface to form a hard shell
(3) Box is repositioned so loose uncured particles drop away
(4) Sand shell is heated in oven for several minutes to complete curing.
(5) shell mold is stripped from pattern.
(6) Two halves of the shell mold are assembled, supported by sand or metal shot in a box, and pouring is
accomplished.
(7) Finished casting with sprue removed
Shell Molding: Advantages and Disadvantages - correct answer ✔-Advantages:
-Smoother cavity surface permits easier flow of molten metal and better surface finish
