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Fundamentals of Solidification

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Title: Fundamentals of Solidification


1
Fundamentals of Solidification
  • Lecture 1 Metal Casting

2
Outline
  • Introduction
  • Preparation of casting
  • Component casting
  • Ingot casting
  • Continuous casting

3
Introduction
  • Solidification and casting
  • Solidification is the process of transformation
    form a liquid phase to a solid phase
  • WikiAnswers
  • Casting is a mass production process which
    involves molten materials being poured into a
    mold, allowed to solidify and then extracted for
    use. tech-faq

4
Introduction
  • History of casting
  • Stone age
  • Copper was used from 6000 years ago
  • Bronze age
  • People knew how to make copper-tin alloys
  • Bronze can also be made by adding Al, Zn, Si, Ni,
    Mn,…
  • Iron is more expensive than gold

5
Bronze
France, 15001300 BC.
6
Bronze
China, 16001046 BC
7
Bronze
National Museum of Korea
8
Introduction
  • History of casting (continued)
  • Iron age
  • Steel is an alloy consisting mostly of iron, with
    a carbon content between 0.2 and 2.04 by
    weight.
  • High melting point Fe 1535 ?C Cu 1083 ?C Si
    1410 ?C Al 660 ?C Sn 232 ?C
  • Steel is stronger than bronze, and easy to sharp.

9
Introduction
  • History of casting (continued)
  • …
  • Modern casting
  • After the middle of 19th century, materials
    qualities were improved by plastic forming,
    forging and rolling.
  • From the middle of 20th century, continuous
    casting has been widely applied.

10
Preparation of casting
  • Preparation of liquid metal
  • Get all materials ready
  • Make suitable composition
  • Melt materials
  • Liquid metal protection
  • Preparation of casting
  • Store and transfer liquid ladle
  • moulds

11
Component casting
  • Melt metal
  • Transfer to ladle
  • Transferred from ladle to mould
  • Solidified

12
Pre-casting moulding
Ancient mould for casting a axe
13
Pre-casting Moulding
  • Principle for the production of moulds
  • Pattern Reproduction of metal component is made
    by wood, plastic, metal or other suitable
    materials.
  • Flask The mould frame is called a flask. The
    pattern is placed in flask.
  • Filling The flask is then filled with moulding
    mixture which is then compact. Moulding mixture
    consists of sand, a binder and water
  • Finishing Pattern is removed and leave cavity
    and core.

14
Pre-casting Moulding
  • Summary of moulding
  • Cavity
  • Core
  • Casting gate or gating system
  • Feeder compensate for the solidification
    shrinkage in the metal.
  • Mould is knocked out
  • Feeders and inlet are removed through cutting or
    oxygen shearing

15
Component casting
16
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17
Component casting
  • Sand mould casting
  • Able to cast 0.1kg 105kg components, suitable
    for single castings as well as for large-scale
    casting, can use hand moulding and large-scale
    machine moulding.
  • Advantage cast most metal, complicated
    component, low initial cost.
  • Disadvantage poor dimensional accuracy, poor
    surface smoothness.

18
Component casting
  • Shell mould casting
  • High dimensional accuracy, good reproduction of
    the shape of the component, good surface
    smoothness, complicated core possible, can cast
    thin walls
  • High code, maximum mass 60-70kg. Large amount to
    profitable

19
Component casting
20
Casting in permanent moulds
  • Moulds are made of cast iron or special steel
    alloy with good resistance to high temperature.
    Mainly used in aluminum, magnesium and zinc
    alloy, difficult for high melting point alloys.

21
Die casting
22
Thixomoulding casting
  • Cast semisolid slurry

23
Ingot casting
  • Metal melt is poured from ladle into moulds where
    it solidifies

24
Ingot casting
  • Downhill casting
  • Uphill casting
  • Advantage?
  • Disadvantage?

25
Continuous casting
  • 1856 Henry Bessemer proposed
  • 1930-1940 Applied in common production of
    nonferrous alloy
  • 1943 steel casting by German scientist Junghans
  • gt90 world production of steel

26
Continuous casting
  • Ladle
  • Stopper
  • Dispenser
  • Shroud
  • Mold
  • Roll support
  • Turning Zone
  • Shroud
  • Bath level
  • Meniscus
  • Withdrawal unit
  • Slab

27
Continuous casting
28
Continuous casting
29
Continuous casting
30
Continuous casting
31
Continuous casting
32
References
  • Hasse Fredriksson and Ulla Åkerlind, Materials
    Processing during Casting, Wiley, (2006).
  • M.C. Flemings, Solidification processing, (1976).
  • http//cml.postech.ac.kr/rqin/gift702/

33
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