Casting

Question 1

Typical Products of Casting

Answer 1

Engine blocks, hub caps, dies and molds, railroad wheels, transmission body car

Question 2

what kind of material

Answer 2

ferrous (iron, steel) and non ferrous (aluminium, etc)

Question 3

advantages of casting

Answer 3

• complex part geomitry
• very large parts
• any metal that can be brang in a liquid state
  some: mass production and net shaping possible

Question 4

disadvantages casting

Answer 4

• limitations on mechanical properties
• porosity
• safety hazards
  -environmental problems
  Sand casting:
• poor dimensional accuracy
• poor surface finish

Question 5

Casting Process

Answer 5

A process in which metals are melted and poured into a die (mold) and solidified

Question 6

Foundry

Answer 6

Place where Casting takes place

Question 7

Foundrymen

Answer 7

Workers

Question 8

Types of Casting

Answer 8

Expandable Molds:
- permanent pattern
- expandable pattern
Permanent molds

Question 9

Sand Casting

Answer 9

Sand: permeable (needed for air), collapsible (casted product shouldnt stick to sand), strength, reusable, thermal stability (high temp.)

Question 10

Process Sand Casting

Answer 10

Pattern + Sand = Mold

Liquid metall –> Mold –> solidifies

Question 11

Parts of Sand Mold

Answer 11

Flask: Supports the mold, consist of cope (top) and drag (bottom)
Pourin Basin: molten metal is poured here
Blind Risers: Supply of additional metal, when solidified metal shrinks
Cores: When you need a hollow part –> inserts

Question 12

Patterns

Answer 12

• Patterns
• -> Used to mold the sand mixture into the shape of the casting and may be made of wood, plastic or metal
• One piece (solid) patterns (easiest)
• split pattern (higher production rate than the others)
• match plate pattern
• cope and drag pattern

Question 13

Sand cores

Answer 13

Placed in the interior of the mold to form the interior surfaces of the part

• Core prints: recesses added to the pattern that locate and support the core, provide vents for gases
• Chaplets: Metal supports to prevent core from shifting

Question 14

Mold Making

Answer 14

90% sand, 3% water
7% clay, resins or other binders

Compaction

• Hand ramming
• Pneumatic pressure
• Mechanical jolting action
• Mechanical slinging action

Question 15

Sand Casting Application

Answer 15

high/low product vol.
all liquid metals
size: very small to very large

Question 16

other casting processes

Answer 16

• shell molding process
• ceramic mold process
• lost foam casting
• investment casting ( similar to lost foam casting)
• hot chamber die casting
• cold chamber die casting

Question 17

Difference Hot & cold chamber die casting

Answer 17

Hot chamber casting: Shot chamber is beeing heated with molten metal in the mold
Cold chamber casting: shot chamber is not heated, molten metal comes seperately in the chamber, injection system is not part of molten metal

Question 18

Production Rate die casting

Answer 18

• higher production rate about 200 pieces /hour

Question 19

Dies for Die casting

Answer 19

• ejector pin push parts out when mold opens
• made of steel
• multiple or single cavity

Question 20

Die Casting general

Answer 20

• no net shaping process (flash has to be removed)
• machines are larges compared to casting because of higher forces and complex mechanical engineering systems
• cooled with oil/water
• cannot be used with molten steel because die is made out of it and would start to melt as well

Question 21

advantages of die casting

Answer 21

-Mold can be reused
-Economical for high production quantities
-Tight tolerances can be achieved (+/- 0.003” for small
parts)
-Good surface finish
-Thin sections are possible (~0.020”)
-Due to rapid cooling: Finer grain structure; stronger
castings

Question 22

Investment casting application

Answer 22

• all types of metal
• normally small parts
• expensive production process