Chapter 10 Metal Casting

Question 1

casting materials

Answer 1

(1) metals,
(2) ceramics, specifically glasses
(3) polymers and polymer matrix composites (PMCs).

Question 2

ingot

Answer 2

simple shape intended for rolling or forging

Question 3

casting advantages (5)

Answer 3

net shape or near net shape
complex geometries (internal and external)
very large parts (100 tons)
any meltable metal
suitable for mass production (limited to certain methods)

Question 4

casting disadvantages (5)

Answer 4

limitations on mechanical properties, porosity,
poor dimensional accuracy and surface finish (some processes),
safety hazards to humans when processing hot molten metals,
environmental problems

Question 5

open mold

Answer 5

metal simply poured into cavity

Question 6

closed mold

Answer 6

metal fills cavity via “gates” through which metal flows

Question 7

expendable mold

Answer 7

mold that is destroyed (one time use)

like sand or plaster

Question 8

permanent mold

Answer 8

reusable metal or ceramic refractory mold that can be opened to remove part

Question 9

cope

Answer 9

upper portion of the mold

Question 10

drag

Answer 10

lower portion of the mold

Question 11

pattern

Answer 11

means by which the mold is created

Question 12

metal _____ as it solidifies

Answer 12

shrinks

Question 13

pattern vs core

Answer 13

pattern determines external geometry

core determines internal part geometry

Question 14

riser

Answer 14

reservoir designed to freeze after the part

Question 15

total heat (formula)

Answer 15

H = rhoV {Cs(Tm - To) + Hf + Cl(Tp - Tm)}
V(volume)[cm^3]
rho(density)[g/cm^3]
Cs(weight specific heat solid metal)[J/gC]
To Tm Tp (Temp, original, melting, pouring)[C}
Hf (heat of fusion) [J/g]
Cl(weight specific heat liquid metal)[J/gC]

Question 16

factors in pouring

Answer 16

temperature, rate and turbulence

TERATU

Question 17

turbulence problems

Answer 17

aggravates mold erosion

accelerates formation of oxides

Question 18

superheat

Answer 18

difference between temp of pouring and temp of solidification

Question 19

factors affecting fluidity

Answer 19

a. Viscosity of the liquid metal
b. Heat transfer to the surroundings
c. Pouring temp vs melting temp
d. Metal composition
4VIHTSDELTRA

Question 20

eutectic

Answer 20

denoting a mixture of substances (in fixed proportions) that melts or solidifies at a single temperature that is lower than the melting points of the separate constituents or of any other mixture of them.

Question 21

heat of fusion

Answer 21

the amount of heat required to solidify the metal from the liquid state.