investment casting

Some of the common defects occur during the manufacture of investment precision castings. We will recommend them to analyze the cause and provide basic solutions for them. Manufacturing is complex because it is a multi-step process. It is less avoidable that some investment casting defects occur due to incorrect operations. With the help of this blog, you will know about common defects in our investment casting foundry.

Defects in Investment Casting

  • Gas hole:

Gas holes are holes that exist in the casting surface or internal space. When the coolant cools and hardens or Bubbles are formed because the solid form of the metal cannot hold as much gas as the liquid form. And These bubbles appear in cavities, round, or perforated casings. They can be spherical, oval, or irregularly shaped.

Sometimes it is an air mass composed of many gas holes. The internal gas hole is usually pear-shaped. The shape of the choke hole is an uneven and rough surface. Gas nests are dents on the surface, and the surface is smoother.

  • Shrinkage:

The shrinkage occurs because metals are less dense than liquids than solids. The shrinkage cavity is a rough-surfaced hole in the casting surface or inside. Slight shrinkage channels are many scattered small shrinkage channels. In other words, shrinkage is a casting depression that occurs during the solidification process. 

The granules of the contraction cavity are large and thick. Usually occurs in sprue, riser root, thick area, thin thickness or wall connection area, etc. And The shrinkage porosity appears with an angular edge relative to the round surface of the gas pore. 

Cavities may be paired with dendritic fractures. Large shrinkage cavities can undermine the integrity of the casting and may eventually fracture under stress. This is one of the common defects of our investment casting foundry.

  • Sand holes:

Sand holes are formed on the casting surface or inside and are quite consistent. But The shape is proportional to the shape of the sand. When removing the investment casting from the mould, we can see grains of sand embedded in the casting surface.

investment casting

Defects in Casting:

Die casting defects occur during the process of pouring metal into the mould. We list the types of casting defects caused by pouring.

  • Cold shut: Cold shut is a type of surface crack with rounded edges. The middle is separated by a scale. And You will see lines or cracks with rounded edges on the casting surface and this defect is visible to the naked eye. A cold shut often appears on the top wall of the casting.
  • Slag: Slag is a clear or unclear hole in the casting. It is partially or partially filled with slag, and the shape is irregular. Small-sized slags are not easy to find. After removing the slag, it will form a smooth hole. They are generally distributed at the bottom of the pouring position.  
  • The oxide slag disperses like a mesh in the casting surface near the sprue. However sometimes a thin sheet or a cloud that is uneven or wrinkled or forming a scale or looks like a lump in the inner part of the casting

Also Read: The Big Challenges that the Casting Industries are Facing Presently


Knowledge of casting defects and their causes is the key to casting quality management. And To prevent product defects in casting products is to establish clear tolerances and quality standards between suppliers and manufacturers before production. In our foundry, we will make a trial order sample as standard and confirm with our customers.

When all details are confirmed, we also start mass production. Our precision casting quality control department is the most stringent in the manufacturing process. Their normal standard is 0 investment casting defects. And  If you have any questions or orders, please feel free to place an order with us and you will get a satisfactory answer in our investment casting foundry.


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