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ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
1
Casting Processes
ver. 2
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
2
Types of Parts Made
• Engine blocks
• Pipes
• Jewelry
• Fire hydrants
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
3
Complex, 3-D shapes
• Near net shape
• Low scrap
• Relatively quick process
• Intricate shapes
• Large hollow shapes
• No limit to size
• Reasonable to good surface finish
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
4
Processes
• Sand
• Shell
• Plaster
• Ceramic
• Investment
• Lost foam
• Pressure
• Vacuum
• Die
• Centrifugal
• Squeeze
• Semi-solid
• Single crystal
• Directional
solidification
• Slush
• Continuous
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
5
Metals processed by casting
• Sand casting – 60%
• Investment casting – 7%
• Die casting – 9%
• Permanent mold casting – 11%
• Centrifugal casting – 7%
• Shell mold casting – 6%
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
6
Breakdown of Castings
• Ingots for bulk deformation processing -
85%
• Cast to near net shape - 15%
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
7
Ingots
• Iron or steel molds
• Water-cooled molds
• Continuous casting
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
8
Shapes
• Expendable Molds
– sand
– shell
– slurry
– investment
• lost wax
• lost foam
• Permanent mold
(cavity)
– die casting
– hot chamber
– cold chamber
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
9
Shapes
• Centrifugal
– pipes
– spinning
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
10
Capabilities
• Dimensions
– sand casting - as large as you like
– small - 1 mm or so
• Tolerances
– 0.005 in to 0.1 in
• Surface finish
– die casting 8-16 micro-inches (1-3 mm)
– sand casting - 500 micro-inches (10-25 mm)
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
11
Casting Steps quick route from raw material to finished
product
• Melt metals
• Pour / force liquid into hollow cavity
(mold)
• Cool / Solidify
• Remove
• Finish
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
12
Melting
• Raw material (charge)
– scrap, alloying materials
• Atmosphere
– Air (oxygen), vacuum, inert gas (argon)
• Heating
– External - electric, gas, oil
– Internal - induction, mix fuel with charge • steel making in blast furnace -mix coke with iron
• Furnace material
– refractory ceramics
Heat
Raw materials
Furnace
Atmosphere
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
13
Furnaces
Blast furnace Basic Oxygen Furnace
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
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Furnaces
Electric Arc Furnace
Oxygen-Fuel,
Oxygen Lance Furnace
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
15
Furnaces
Induction Furnace Electric Furnace
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
16
Sand Casting
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
17
Sand Casting
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
18
Sand Casting
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
19
Sand Casting Steps
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
20
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
21
Sand Cast Parts
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
22
Permanent Mold Casting
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
23
Low Pressure Casting
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
24
Die Casting (high pressure)
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
25
Die Casting Machine
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
26
Die Casting
Cold chamber
Hot chamber
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
27
Direct Squeeze Casting
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
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Die Casting Part Example
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
29
Continuous Casting
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
30
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
31
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
32
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
33
Investment
Casting
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
34
Vacuum Casting
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
35
Investment (top) and Conventional
Castings
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
36
Lost Foam Casting
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
37
Lost Foam Castings
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
38
Centrifugal Casting
vertical sand-lined mold
casting
horizontal
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
39
Centrifugal Casting
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
40
Pipe Casting
Process
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
41
Directional Solidification
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
42
Casting Characteristics Table 5.6
Typical Weig ht (kg)
Typical
surface
Section
thickness (mm)
Process
materials
cast Minimum Maximum
finish
(micron,
Ra) Porosity*
Shape
complexity
*
Dimensional
accuracy* Minimum Maximum
Sand All 0.05 No limit 5-25 4 1-2 3 3 No limit
Shell All 0.05 100+ 1-3 4 2-3 2 2 --
Expendable
mold
pattern All 0.05 No limit 5-20 4 1 2 2 No limit
Plaster
mold
Nonferrou
s (Al, Mg,
Zn, Cu) 0.05 50+ 1-2 3 1-2 2 1 --
Investment
All
(High melting
pt.) 0.005 100+ 1-3 3 1 1 1 75
Permanent
mold All 0.5 300 2-3 2-3 3-4 1 2 50
Die
Nonferrou
s (Al, Mg,
Zn, Cu)
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
43
Microstructure
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
44
Microstructure - Dendrites
• Finer structure at
walls
• Grains / dendrites
grow to center
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
45
Grains on Willie B’s head
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
46
Microstructure - Dendrites
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
47
Fluidity
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
48
Casting Defects - Porosity
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
49
Casting Defects
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
50
Shrinkage
TABLE 5.1
Metal or alloy
Volumetric
solidification
contraction (%) Metal or alloy
Volumetric
solidification
contraction (%)
Aluminum 6.6 70%Cu–30%Zn 4.5
Al–4.5%Cu 6.3 90%Cu–10%Al 4
Al–12%Si 3.8 Gray iron Expansion to 2.5
Carbon steel 2.5–3 Magnesium 4.2
1% carbon steel 4 White iron 4–5.5
Copper 4.9 Zinc 6.5
Source: After R. A. Flinn.
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
51
Differential Cooling
• Transition between thicker and thinner
sections can lead to porosity
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
52
Pipe Defect
• Due to shrinkage giving rise to
a funnel-like cavity
• Solutions
– insulate top (glass wool)
– heat top (exothermic mixture -
thermit)
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
53
Defects - Hot Tears
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
54
Chills
Car Rims
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
55
Stamped Cast
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
56
Casting Defects - Porosity
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
57
Design Rules Summary
• Uniform wall thickness
• Flat parting lines
• Gradual thickness
transitions
• Draft for removal
– tapers: 0.5 to 2 degrees
• Surface of mold gives
surface of part
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
58
Sand Casting Rules
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
59
Casting costs
TABLE 5.10
Cost*
Process Die Equipment LaborProductionrate (Pc/hr)
Sand L L L–M
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
60
Process economics
ME 4210: Manufacturing Processes and Equipment
Prof. J.S. Colton © GIT 2011
61