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When gases are entrapped on the surface of casting due to solidification of metal then oval cavity is formed. This type of casting defect is known as:

When gases are entrapped on the surface of casting due to solidification of metal then oval cavity is formed. This type of casting defect is known as: Correct Answer Blowholes

Explanation:

Blow holes:

Blow holes, gas holes, or gas cavities are well-rounded cavities having a clean and smooth surface. They appear either on the casting surface or in the body of a casting.

These defects are caused by: 

  • Excessive moisture content.
  • Inadequate gas permeability of the moulding sand i.e. gases are entrapped on the surface of casting due to solidification.
  • Low pouring temperature.

Additional Information

Defect Description Diagram
Cold Shut

Improper fusion of two streams of liquid metal

Causes:

  • Defective or improper ramming of the mould.

 
Drop Drop defect occurs when there is cracking on the upper surface of the sand and sand pieces fall into the molten metal.

Cause:

  • Soft ramming and low strength of sand.
  • Insufficient reinforcement of sand projections in the cope.
       

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