CH 8 Multiple Choice Q's

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: (a) true or (b) false?

True

The Antioch process is similar to plaster-mold casting but uses a mixture of sand and plaster to make the mold: (a) true or (b) 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: (a) true or (b) false?

True

Which of the following casting processes are expendable mold operations: (a) centrifugal casting, (b) die casting, (c) investment casting, (d) low pressure casting, (e) sand casting, (f) shell molding, (g) slush casting, and (h) vacuum molding?

investment casting, sand casting, shell molding, vacuum molding

In sand casting, the volumetric size of the pattern is (a) bigger than, (b) same size as, or (c) smaller than the cast part?

Bigger than

Silica sand has which one of the following compositions: (a) Al2O3, (b) SiO, (c) SiO_2, or (d) SiSO_4?

SiO_2

Which of the following casting processes are permanent mold operations: (a) centrifugal casting, (b) expanded polystyrene process, (c) sand casting, (d) shell molding, (e) slush casting, and (f) vacuum molding.

Slush casting, die casting, centrifugal casting

Which one of the following casting metals is most important commercially: (a) aluminum and its alloys, (b) bronze, (c) cast iron, (d) cast steel, or (e) zinc alloys?

cast iron

Which of the following qualifies as a precision-casting process: (a) ingot casting, (b) investment casting, (c) plaster-mold casting, (d) sand casting, and (e) shell molding?

Investment casting, plaster-mold casting

Which of the following metals would typically be used in die casting: (a) aluminum, (b) cast iron, (c) steel, (d) tin, (e) tungsten, and (f) zinc?

aluminum, tin, zinc

Which of the following are advantages of die casting over sand casting (four best answers): (a) better surface finish, (b) closer tolerances, (c) higher melting temperature metals can be cast, (d) higher production rates, (e) larger parts can be cast, and (f) mold can be reused?

higher production rates, closer tolerances, better surface finish, mold can be reused

A misrun is which one of the following defects in casting: (a) globules of metal becoming entrapped in the casting, (b) metal is not properly poured into the downsprue, (c) metal solidifies before filling the cavity, (d) microporosity, and (e) "pipe" formation?

metal solidifies before filling the cavity

For which one of the following reasons is a green mold named: (a) green is the color of the mold, (b) moisture is contained in the mold, (c) the mold is cured, or (d) the mold is dry?

moisture is contained in the mold

An irregularity in the surface of the casting caused by erosion of the sand during pouring is called which one of the following sand casting defects: (a) penetration, (b) sand blow, (c) sand wash, or (d) scabs?

sand wash EXTRA -> - penetration: fluidity of the liquid metal is high, and penetrates into the sand mold or sand core. - sand blow: a balloon-shaped gas cavity caused by release of mold gases during pouring. - scabs: rough areas on the surface of the casting due to encrustations of sand and metal.

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: (a) centrifuge casting, (b) semicentrifugal casting, or (c) true centrifugal casting?

true centrifugal casting

Which of the following are metals commonly cast in permanent mold casting (three best answers): (a) aluminum, (b) brass, (c) gold, (d) magnesium, (e) nickel, (f) steel, and (g) tungsten?

Aluminium, magnesium, brass (copper-based alloy) EXTRA -> cast iron

Cupolas are furnaces used to melt which of the following metals: (a) aluminum, (b) cast iron, (c) steel, or (d) zinc?

Cast iron

Which one of the following casting processes is the most widely used: (a) centrifugal casting, (b) die casting, (c) investment casting, (d) sand casting, or (e) shell casting?

Sand casting

Given that Wm = weight of the molten metal displaced by a core and Wc = weight of the core, the buoyancy force is which one of the following: (a) downward force = Wm + Wc, (b) downward force = Wm - Wc, (c) upward force = Wm + Wc, or (d) upward force = Wm - Wc?

upward force = Wm - Wc

In plaster mold casting, the mold is made of which one of the following materials: (a) Al2O3, (b) CaSO4-H2O, (c) SiC, or (d) SiO2?

CaSO_4-H_2O

Shell molding is best described by which one of the following: (a) casting operation in which the molten metal has been poured out after a thin shell has been solidified in the mold, (b) casting process in which the mold is a thin shell of sand bonded by a thermosetting resin, (c) sand-casting operation in which the pattern is a shell rather than a solid form, or (d) casting operation used to make artificial sea shells?

Casting process in which the mold is a thin shell of sand bonded by a thermosetting resin.

Investment casting is also known by which one of the following names: (a) fast-payback molding, (b) full-mold process, (c) lost-foam process, (d) lost-pattern process, or (e) lost-wax process?

lost-wax process

Which of the following names are applied to a process 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: (a) liquid-metal casting, (b) liquid-metal forging, (c) rheocasting, (d) squeeze casting, or (e) thixocasting?

squeeze casting, liquid-metal forging