Transcript Sand Casting making by: Mahmod abd elnabe 120072426

Sand Casting
making by:
Mahmod abd elnabe
120072426
Sand
casting
Is metal
casting process characterized by
using sand as the mold material . It is
relatively cheap and sufficiently
refractory even for steel foundry use.
Basic process
 There are six steps in this process
1)
2)
3)
4)
5)
6)
Place a pattern in sand to create a mold.
Incorporate the pattern and sand in a gating
system.
Remove the pattern.
Fill the mold cavity with molten metal .
Allow the metal to cool .
Break away the sand mold and remove the
casting.
Sands
• Silica sand (SiO2)
• Two general types of sand:
 Naturally bonded (bank sand)
 synthetic (lake sand)
Several factors affect the selection
of sand for molds.
• Sand having fine, round grains can be closely packed and forms a
smooth mold surface.
• Although fine-grained sand enhances mold strength, the fine grains
also lower mold permeability
• Good permeability of molds and cores allows gases and steam evolved
during casting to escape easily.
• The mold should have good collapsibility (to allow for the casting to
shrink while cooling to avoid defects in the casting, such as hot tearing
and cracking.
Types of Sand Molds
Green-sand.
Is a mixture of sand, clay, and water
Cold-box.
Various organic and inorganic binders are blended into the sand to
bond the grains chemically for greater strength.
No-bake molds.
A synthetic liquid resin is mixed with the sand; the
mixture hardens at room temperature.