Common Defects of Iron Castings

An unwanted abnormality in a metal casting process can result in a casting defect. We list out some of the common defects of iron castings.

Air Hole

Flat holes of varying sizes appear on iron castings when the moulding sand has high water content, no proper ventilation, when the mould is poured too fast, etc.

Scattered contraction

You will find cavities most often at a 90 degree angle to the casting surface. The casting defect in iron components is usually caused by irregularities in carbon or nitrogen content in the melt.

Projections at the separation line

This happens when metal gets into the clearance between the top and bottom of the metal casting mould halves. To avoid projections the metalcaster must take extra caution during pattern, mould and core making.


Shrinkage is often seen in segment positions of castings. It will have an uneven shape with bumpy holes. The defect is due to imperfect gating system or if the riser is too small. Shrinkage can also happen when the pouring temperature is too high.


Sand holes, which are sand filled holes on the interior or exterior of iron castings, are a commonly seen defect. This defect can happen when the moulding sand is not of the correct strength.


If the iron casting is not given adequate melting time during its making, it can result in slag. The defect could also be due to some damage in the filter, or if the pouring temperature was too low.

Staggered box

Staggered box causes the staggered positions at the separation line of the castings. Staggered box is due to the incorrect location of top sand box and down sand box. The sand boxes should be aligned properly to avoid the defect.

Sticky sand

The exterior of iron castings is joined securely by sand, and this is what gives it a rough appearance. Sticky sand is caused when there is insufficient sand to resist fire. Like all the other common defects, this defect occurs when the pouring temperature is too high.

Axial Shrinkage

All metal contracts as it harden. Axial shrinkage happens when the metal at the centre of the casting takes more time to freeze than the metal surrounding it. This defect is mostly caused by uneven casting thickness. Pouring temperature and speed, and alloy clarity can also cause this defect.

Fillet Vein

This defect is due to too much binder in the sand. As a result a gap is formed in the mould during mould preparation or casting. The defect can be prevented by reducing the use of binder.


Sand contraction due to heat can cause this defect. To prevent cracks on a sand mould the metalcaster must adjust its sand composition and heating.

Cold Shot

This defect occurs when metal drops fall into a casting mould. These drops will soon harden and won’t melt when the remaining metal is introduced to the mould. Incorrect pouring practices can cause this defect. Metalcasters must try to improve pouring conditions to avoid this defect.