Chapter 11 Metal Casting Processes
Which three of the following metals would typically be used in die casting?
Aluminum, tin, and zinc
Compared to sand casting, shell molding has which four of the following features:
Better dimensional accuracy, better surface finish on casting, easier flow of molten metal during, more expensive metal pattern is required
An indirect fuel-fired furnace is an alternative name for which one of the following furnace types?
Crucible furnace
In hot-chamber die-casting machines, molten metal is poured into an unheated chamber from an external melting container, and a piston is used to inject the metal under high pressure into the die cavity. True or False?
False
Most commercial nonferrous casting metals are not alloys because the melting temperatures of alloys are higher. True or False?
False
Semi-solid metal casting is a family of net-shape and near net-shape processes performed on metal alloys at temperatures between the liquidus and solidus, so that the casting operation is performed on molten metal in which some dendrite formation has already occurred. True or False?
False
Which three of the following are other names for the expanded-polystyrene casting process?
Evaporative-foam process, lost-foam process, and lost-pattern process
An advantage of a plaster mold that is permeable, thus allowing escape of gasses from the mold cavity?
False
Which one of the following casting processes are capable of the closest tolerances for parts of the same size and metal?
Investment casting
Which two of the following names are applied to processes in which a molten metal is poured into a heated lower die, and the upper die is closed to create the mold cavity only after solidification begins?
Liquid-metal forging, and squeeze casting
Investment casting is also known by which one of the following names?
Lost-wax process
Thixomolding is a semi-solid metal casting process used for which one of the following metals?
Magnesium
A misrun is which one of the following defects in casting?
Metal solidifies before filling the cavity
To make molds containing multiple cavities, the individual patterns are attached to a structure called which one of the following?
Pattern tree
The mold in investment casting is made of which two of the following materials?
Plaster and silica
Surface cleaning of the solidified casting is most important in which one of the following casting processes?
Sand casting
Which one of the following casting processes is the most widely used?
Sand casting
An irregularity in the surface of the sand casting caused by erosion of the sand during pouring is called which one of the following?
Sand wash
Silica sand has which one of the following chemical compositions?
SiO2
Which one of the following products would not be an appropriate application for zinc casting?
Structural beam
Ceramic-mold casting is similar to plaster-mold casting, except that the mold is made of refractory ceramic materials that can withstand higher temperatures than plaster. True or False?
True
In the expanded-polystyrene casting process, a new pattern and a new mold are required for every casting produced?
True
Machining allowance refers to additional material left on the casting to machine surfaces or geometric features that cannot be achieved in the casting operation. True or false?
True
Slush casting is a permanent-mold process in which a hollow casting is formed by inverting the mold after partial freezing at the mold surface to drain the liquid metal in the center?
True
Steel can be cast in permanent-mold processes, but because of its high melting temperatures, the mold must be made of a refractory material. True or False.
True
The expanded-polystyrene casting process uses a mold of sand packed around a polystyrene foam pattern that vaporizes when the molten metal is poured into the mold. True or False?
True
The fabrication cost of the mold in expendable mold processes is a component in the total cost to produce each casting because each casting requires its own mold, whereas in permanent mold casting processes, the mold cost is apportioned over the quantity of parts made throughout the life of the mold. True or False
True
Unlike expendable molds, permanent molds do not collapse so the mold must be opened before appreciable cooling contraction occurs in order to prevent cracks from developing in the casting. True or False
True
Which one of the following is the name of the casting process in which molten metal is poured into a rotating mold to produce a tubular part?
True centrifugal casting
Low-pressure casting and vacuum permanent-mold casting are similar. Which one uses lower-than-atmospheric air pressure in the mold to draw the molten metal into the cavity?
Vacuum permanent-mold casting
In which of the following tube casting processes is the casting wall thicker at one end of the tube than at the other end?
Vertical centrifugal casting
When splattering occurs during pouring, solid globules of metal can become entrapped in the casting; this defect is called which one of the following?
cold shot
For which one of the following reasons is a green mold named?
moisture is contained in the mold
The power generated by a certain heating furnace is 200 kW and its thermal efficiency = 40%. The unit energy for melting and pouring for the casting metal = 800 J/g, and the total weight of the metal to be heated in the furnace = 50 kg. The time required to heat the metal for pouring is closest to which one of the following?
8 minutes
Which three of the following are metals commonly cast in permanent mold casting?
Aluminum, brass, and magnesium
Which four of the following are advantages of die casting over sand casting?
Better, closer tolerances, higher production rates, and mold can be reused
Relative to the size of the cast part in sand casting, the volumetric size of the pattern is which one of the following?
Bigger
In plaster mold casting, the mold is made of which one of the following materials?
CaSO4-H2O
Cupolas are furnaces used to melt which one of the following metals?
Cast iron
Which one of the following casting metals is most important commercially?
Cast iron
Shell molding is best described by which one of the following?
Casting process in which the mold is a thin shell of sand bonded by a thermosetting resin
Radial symmetry is not a requirement in which one of the centrifugal casting processes?
Centrifuge casting
