Common Defects of Iron Castings
Learning the common
iron casting defects
is important for the iron casting
purchasers. The buyers should be able to
judge the common defects and give an
reasonable treatment advices to the
There are many different defects in
castings, and knowing the defects and
their causes are complex, and sometimes
many different defects can be seen on
the same appear on the castings.
In general, castings with a slight
defects can be used directly. Castings
with medium defects should be allowed to
repair before use. If there are serious
flaws in castings, only scrapped.
According to the working experience in
Dandong Foundry, I listed the common
casting defect types and causes as
1. Air Hole
Air hole is the internal casting
porosity or surface smooth holes of
It is because that molding sand has too
much water, poor ventilation, sand core
or sand core has bad drying, pouring
temperature is too low or pouring too
fast and so on.
Shrinkage is located in section
positions of castings. It is irregular
shape with rough holes.
Casting shrinkage is because that gating
system is incorrect, or the riser is too
small; pouring temperature is too high,
or the chemical composition of metal is
Trachoma is also called
sand hole, which
is sand filled holes in the internal or
on the surface of the castings.
Trachoma is due to the bad strength of
molding sand, sand molds have part
damage, gating system is irrational.
Slag is because the melting time is not
sufficient, the cold metal left in the
ladle, the filter is not good, pouring
temperature is too low.
Staggered box causes the staggered
positions at the
parting line of the
Staggered box is because that the wrong
position of top sand box and down sand
box, the upper and lower sand box is not
The surface of castings is bonded by
sand, so looks very rough.
Sticky sand is because the sand is not
enough for fire resistance, pouring
temperature is too high, no painting
brush or painting too thin.
For more metal casting defects and pictures, please refer to "Metal Casting Defects".