Ch. 6 Sand

Question 1

What is permeability

Answer 1

the ability of how well gases can vent and pass through sand

Question 2

What is purpose of Methylene Blue test

Answer 2

To test the amount of active clay in green sand

Question 3

What is the problem with silica sand

Answer 3

it tends to contract heavily when exposed to high-temperature alloys

Question 4

What is AFS GFN

Answer 4

Grain Fineness Number. Measure of grain size and sand distribution

Question 5

What properties do sands with more round and spherical grains have

Answer 5

has harder time allowing air to escape

Question 6

what is a fractured sand grain called?

Answer 6

fine

Question 7

what are the advantages of chromite and zircon sand

Answer 7

very heavy sand, and good hardness

Question 8

how is GFN related to grain size

Answer 8

indirectly proportional to grain size

Question 9

what is a misrun

Answer 9

when the molten metal freezes before it reaches all parts of the mold cavity.

Question 10

what is Clay used in green sand

Answer 10

a binder

Question 11

2 main types of clay in green sand

Answer 11

Southern bentondite popular wiht aluminum. Western bentonite is popular with ferrous-based alloys.

Question 12

what is a calcinator

Answer 12

soemthing that melts a compound

Question 13

what is sand reclamation

Answer 13

when foundries remove part of their used sand and treats it to resotre the sand’s properties

Question 14

what is water used in green sand

Answer 14

an activator

Question 15

what are carbonaceous materials used for in green sand

Answer 15

to provide a good surface finish

Question 16

what are 4 heat-activated procces

Answer 16

1. shell 2. oil sand 3. cold box 4. silicon-based

Question 17

what is compactibility

Answer 17

the ability of sand to be rammed under an applied load. measured in density.

Question 18

what does active clay do

Answer 18

sand which retains it’s binding force absorbs the moisture of sand

Question 19

what are additives in green sand

Answer 19

a 4th material used to enhance the specific properties of green sand

Question 20

what are common additives in green sand

Answer 20

carbonaceous materials, cereal, iron oxide

Question 21

what does carbonaceous materials due to the green sand

Answer 21

allows for a good surface finish

Question 22

what is the difference between batch muller and continuous muller

Answer 22

batch muller: mixes a given amount of molding materials at a time and discharges it before a fresh one is fed. continuous muller mixes a continuous stream of sand as it passes through the mixing unit.

Question 23

how is grain size related to permeability

Answer 23

directly proportional. this is because as the gaps between particles increase the ability of fluids and air to travel through it becomes easier.

Question 24

permeability of sand formula

Answer 24

( volume of air x height of specimen) / ( area of specimen times pressure of air x time in minutes it takes for a sand specimen to cross the specimen)

Question 25

round grains have blank permeability

Answer 25

low permeability

Question 26

angular grains have blank permeability

Answer 26

high