Chapter 10 Multiple Choice

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 (two correct answers): (a) blind riser (b) open riser (c) side riser (d) top riser

(a) blind riser (c) side riser

In foundry work, a runner is which of the following: (a) channel in the mold leading from the downsprue to the main mold cavity (b) foundryman who moves the molten metal to the mold (c) vertical channel into which molten metal is poured into the mold?

(a) channel in the mold leading from the downsprue to the main mold cavity

The upper half of a sand-casting mold is called which of the following: (a) cope (b) drag

(a) cope

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

(a) expandable mold

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 (d) time to give up the heat of fusion

(a) time between pouring and complete solidification

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

(b) box which holds the cope and drag

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

(b) greater than

Turbulence during pouring of the molten metal is undesirable for which of the following reasons (two best answers): (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 (f) it increases total solidification time

(c) it increases erosion of the mold surfaces (d) it increases the formation of metallic oxides that can become entrapped during solidification

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 (e) waste metal that is usually recycled

(c) metal that is not part of the casting (d) source of molten metal to feed the casting and compensate for shrinkage during solidification (e) waste metal that is usually recycled

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 (e) solidus

(d) mushy zone

Chvorinov's rule states that 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 (f) (V/A)^2

(f) (V/A)^2