Casting MFE2010

Which of the following casting processes is not an expendable mold operation ? (a) investment casting, (b) low pressure casting, (c) sand casting, (d) shell molding,

B

Which of the following is not an advantage of die-casting over sand casting (a) better surface finish, (b) suitable for casting higher melting temperature metals, (c) higher production rates (d) mold can be reused.

B

Which of the following molds is more suited for casting of high melting point metals a. plaster b. ceramic c. rubber d. a & c e. b & c

B

Which of the following qualifies as a precision casting process ? (a) ingot casting, (b) investment casting (c) plaster mold casting (d) sand casting,

B

The best designed risers are a. as close as possible to being spherical in shape b. located in extremities of the mold c. all of the above is true d. none of the above

C

The microstructure of the metal adjacent to mold cavity tends to be (a). Chilled fine grains (b). Coarse grains (c). randomly oriented (d). a & c (e). b & c

C

The upper half of a sand casting mold is called which of the following? (a) flask, (b) drag. (c) cope

C

Which of the following casting processes is not a permanent mold operation? (a) die casting (b) low pressure casting (c) shell molding (d) slush casting, and (e) vacuum mold casting.

C

Which of the following metals would not typically be die casted ? (a) aluminum (b) tin, (c) tungsten, (d) zinc.

C

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

C

A riser in casting is not described by which of the following ? (a). casting that inhibits buoyancy of the core, (b) part of mold system which helps directional solidification. (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.

A

In sand casting, the volumetric size of the pattern is which of the following relative to the cast part? (a) bigger, (b) same size (c) smaller.

A

Sand casting is which of the following types? (a) Expendable mold, (b) permanent mold. (c) neither

A

Cupolas are furnaces used to melt which of the following metals (choose one best answer)? (a) aluminum (b) cast iron (c) steel (d) zinc.

B

In a sand casting mold, the V/A ratio of the riser should be which one of the following relative to the V/A ratio of the casting itself? (a) equal, (b) greater, or (c) smaller.

B

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

B

Runner extensions can be used to a. feed into outer areas of the cavity b. trap first metal c. provide compensation for solidification d. all of the above is true e. none of the above

B

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 down sprue, (c) metal solidifies before filling the cavity, (d) microporosity, and (e) "pipe" formation.

C

Alloys with high melting point temperature generally uses a. short gating system b. open gating system c. both of the above d. none of the above

C

During pouring of molten metal oxides forming a. are dross or slag b. can be reduced or eliminated by use of flux c. can be reduced or eliminated by use of vacuum d. all of the above is true e. none of the above

C

If the molten metal speed a. is high it may cause erosion of mold wall b. is low it may cause miss runs and cold shuts c. both of the above are true d. none of the is above

C

In foundry work, a runner is which one of the following? a. vertical channel into which molten metal is poured into the mold. b. foundryman who moves the molten metal to the mold, or c. channel in the mold leading from the down sprue to the main mold cavity, d. None of the above

C

Poor fluidity can lead to a. miss runs b. cold shuts c. both of the above d. none of the above

C

Shell molding is 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 operation used to make artificial seashells, (c) casting process in which the mold is a thin shell of sand bonded by a thermosetting resin, or (d) sand casting operation in which the pattern is a shell rather than a solid form.

C

Silica sand has which one of the following compositions? (a) A1203, (b) SiG, (c) SiO2, (d) SiSO4.

C

Alloys with large freezing range of solidification a. give more troubles because it makes compensation through risers difficult b. allow ample time for the still hot molten metal in the riser to move back into the cavity of the mold c. the resultant structure contains numerous small shrinkage pores d. a & c e. b & c

D

Based on Chvorinov's Rule, a. A good shape for a riser would one with a small area per unit volume. b. The ideal and practical shape would a sphere. c. To the patternmaker and mold designer the best practical shape for a casting riser would probably be a cylinder with height approximately equal to the diameter. d. a & c e. none of the above.

D

Design of gating involves a number of factors like : a. Metal should enter the cavity with as little turbulence as possible. b. Erosion of passageways should be avoided. c. Directional solidification should be observed. d. All of above. e. None of above.

D

In casting, a flask is which one of the following? a. beverage bottle for foundrymen, b. box which is composed of cope and drag, c. container for holding liquid metal, or d. metal which extrudes between the mold halves.

D

Limitations of die-casting include the following a. High cost of equipment and die. b. Rapid reduction in die life as metal temperature increases. c. Metal having a high coefficient of contraction must be removed as soon as possible. d. All of above.

D

Sand grain size and shape has direct influence on the quality of the casting a. large grains give good permeability b. large grains give better surface finish c. angular shaped grains give better green strength d. a & c e. b & c

D

The advantages of shell molding process include: a. Close tolerance of 0.002 to 0.005 inch per inch. b. Low cleaning costs. c. Smooth surfaces. d. All of the above. e. None of the above.

D

The factors affecting the fluidity of a molten metal during pouring into a mold cavity? a. pouring temperature, b. the type of sand binder used c. heat transfer to the surroundings. d. a &c e. b & c

D

The following methods use expendable molds a. green and dry sand mold casting b. plaster and ceramic mold casting c. corthias and die casting d. a &b e. a& c

D

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

D

A riser that is completely enclosed within the sand mold and connected to the main cavity by a channel to feed the molten metal is called which of the following (may be more than one)? (a) open riser, (b) blind riser, (c) side riser, (d) top riser. (e) (b) and (c).

E

Cast iron is the most used casting metal because of its a. good fluidity b. high shrinkage c. good strength d. a & b e. a & c

E

Chvorinov's Rule states that total solidification time is proportional to which one of the following quantities? (a) (A/V), (b) Hf, (c) Tm, (d) V (e) (V/A)n where A = surface area of casting, Hf = heat of fusion, Tm = melting temperature, and V = volume of casting.

E

Shape, length and size of cross sections of feeding channels are critical a. short spruces are desirable b. rectangular pouring cups spruces prevent vortex formation c. choke should be moved close to mold gate d. all of the above is true e. a & b

E

The sources of contraction in a metal casting after pouring. a. contraction of the molten metal after pouring, b. solidification shrinkage during transformation of state from liquid to solid, and c. the compressive forces applied by the contracting mold cavity. d. a& b e. a & c

E

To slow the cooling rate a. switch from blind to open risers b. place insulators in the vicinity of the mold cavity c. use endothermic materials to line risers d. a & c e. a & b

E

Semicentrifugal casting is normally used for parts in which the center is to be removed.

T

True centrifugal casting is used for symmetrical objects.

T

Identify some of the important advantages of casting processes. a. complex part geometries are possible; b. some casting operations are net shape processes, meaning that no further manufacturing operations are needed to accomplish the final part shape; c. very large parts are possible; d. applicable to any metal that can be melted; e. All of the above

e

The limitations and disadvantages of casting? a. limitations on mechanical strength properties; b. porosity; c. poor dimensional accuracy d. Safety hazards and environmental problems. e. All of the above

e