CH 7 Multiple Choice Q's

7.3 Sand casting is which of the following types of casting process: (a) expendable mold or (b) permanent mold?

Expendable mold

7.12 Total solidification time is defined as which one of the following: (a) time between pouring and complete solidification, (b) time between pouring and cooling to room temperature, (c) time between solidification and cooling to room temperature, or (d) time to give up the heat of fusion?

time between pouring and complete solidification

7.15 According to the empirical relationship in the previous question, total solidification time is proportional to which one of the following quantities: (a) (A/V)^n, (b) Hf, (c) Tm, (d) V, (e) V/A, or (f) (V/A)^2; where A = surface area of casting, Hf = heat of fusion, Tm = melting temperature, and V = volume of casting?

(V/A)^2

7.10 Turbulence during pouring of the molten metal is undesirable for which of the following reasons: (a) it causes discoloration of the mold surfaces, (b) it dissolves the binder used to hold together the sand mold, (c) it increases erosion of the mold surfaces, (d) it increases the formation of metallic oxides that can become entrapped during solidification, (e) it increases the mold filling time, and (f) it increases total solidification time?

- it increases erosion of the mold surfaces - it increases the formation of metallic oxides that can become entrapped during solidification

7.18 A riser in casting is described by which of the following (three correct answers): (a) an insert in the casting that inhibits buoyancy of the core, (b) gating system in which the sprue feeds directly into the cavity, (c) metal that is not part of the casting, (d) source of molten metal to feed the casting and compensate for shrinkage during solidification, and (e) waste metal that is usually recycled?

- metal that is not part of the casting - source of molten metal to feed the casting and compensate for shrinkage during solidification - waste metal that is usually recycled

7.11 Two important relationships that determine the flow of molten metal in casting are which of the following: (a) Bernoulli's theorem, (b) Chvorinov's rule, (c) continuity law, (d) flow curve, (e) Hooke's law, or (f) Ohm's law?

Bernoulli's theorem Continuity law

7.20 Which of the following riser types are completely enclosed within the sand mold and connected to the main cavity by a channel to feed the molten metal: (a) blind riser, (b) open riser, (c) side riser, and (d) top riser?

Blind riser, side riser

7.14 The empirical relationship that determines total solidification time in casting is known as which one of the following: (a) Bernoulli's theorem, (b) Chvorinov's rule, (c) continuity law, (d) flow curve, (e) Hooke's law, or (f) Ohm's law?

Chvorinov's rule

7.4 The upper half of a sand-casting mold is called which one of the following: (a) cope, (b) drag, (c) flask, or (d) pattern?

Cope EXTRA -> bottom half: drag box holding halves: flask

7.2 A factory that performs casting processes is called which of the following: (a) casting plant, (b) foundry, (c) ingot-making plant, (d) metal working plant, or (e) molding plant?

Foundry

7.19 In a sand-casting mold, the V/A ratio of the riser should be (a) equal to, (b) greater than, or (c) smaller than the V/A ratio of the casting itself?

Greater than

7.9 Heating a metal from room temperature to pouring temperature in a casting operation depends on all of the following properties except which one: (a) density, (b) heat of fusion, (c) melting temperature, (d) specific heat, or (e) thermal expansion?

Melting temperature, specific heat, heat of fusion

7.13 During solidification of an alloy when a mixture of solid and liquid metals is present, the solid-liquid mixture is referred to as which one of the following: (a) eutectic composition, (b) ingot segregation, (c) liquidus, (d) mushy zone, or (e) solidus?

Mushy zone

7.1 Casting is a process in which molten metal flows into a mold where it solidifies in the shape of the mold cavity; the term casting also applies to the part that is made by this process: (a) true or (b) false?

True

7.5 In casting, a flask is which one of the following: (a) beverage bottle for workers who perform casting, (b) box which holds the cope and drag, (c) container for holding liquid metal, or (d) metal which extrudes between the mold halves?

box which holds the cope and drag

7.7 In casting processes, a runner is which one of the following: (a) channel in the mold leading from the downsprue to the main mold cavity, (b) worker who moves the molten metal to the mold, or (c) vertical channel into which molten metal is poured into the mold?

channel in the mold leading from the downsprue to the main mold cavity

7.16 Solidification shrinkage in casting is defined as which one of the following: (a) liquid contraction during cooling prior to solidification, (b) liquid contraction during cooling and solidification, (c) contraction during the phase change from liquid to solid, or (d) thermal contraction of the solidified casting during cooling to room temperature.?

contraction during the phase change from liquid to solid

7.8 The internal surfaces of a casting are determined during the casting process by means of which one of the following: (a) core, (b) gating system, (c) parting line, (d) pattern, or (e) sprue?

core

7.17 Metal inserts in the walls of a sand mold cavity designed to remove heat from the molten metal more rapidly than the surrounding sand are called which one of the following: (a) external chills, (b) internal chills, (c) pipes, or (d) sprues?

external chills EXTRA -> internal chills: small metal parts placed inside the cavity before pouring so that the molten metal will solidify first around these parts.

7.6 The pattern that determines the geometry of the casting in expendable mold processes is usually made (a) oversized, (b) the same size, or (c) undersized relative to the dimensions of the casting?

oversized