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