Presentation on some casting defects and solutions

1. Casting defects
Eng: hussein kiswani

2. introduction
 Defects in castings :
 the casting design
 the technique of manufacture–the method
 the application of the technique–‘workmanship’

3. Types of defects
 Shaping faults arising in pouring .
 Inclusions and sand defects.
 Gas defects .
 Shrinkage defects due to volume contraction in the liquid state and during
solidification .
 Contraction defects occurring mainly or wholly after solidification .
 Dimensional errors .
 Compositional error sand segregation .

4. Some of defects for casting
 Misrun
 A casting that has solidified before completely filling mold cavity

5.  the pouring temperature is too low
 the material is poured too slowly
 there is insufficient fluidity in the molten metal
 there is insufficient material to fill the mould
All of these issues can be resolved through
good process design.

6. Cold Shut
 Two portions of metal flow together but there is a lack of fusion due to
premature freezing

7.  The fluidity can be increased by changing the
chemical composition of the metal or by
increasing the pouring temperature

8. Shrinkage Cavity
 Depression in surface or internal void caused by
solidification shrinkage that restricts amount of molten
metal available in last region to freeze

9.  Use a large sprue.
The sprue should be thicker than the section of the mold
it is connected to.
 Make sure the gates are cut as wide as possible.
Large gates allow the metal in the sprue to stay warm
from the heat of the main body of the casting. So the
sprue will hopefully cool slower

10. Mold Shift (Common defects in sand castings)
 A step in cast product at parting line caused by sidewise
relative displacement of cope and drag
Mold Shift (Common defects in sand castings)

11.  is to use some type of alignment pins to ensure
the cope and drag align perfectly

12. Sand Blow (Common defects in sand castings)
 Balloon-shaped gas cavity caused by release of
mold gases during pouring

13. Hot tear
 the main reason for formation of hot tears are the geometry of casting