Question

Two streams of liquid metal, which are not hot enough to fuse properly, result into a casting defect known as
1. cold shut
2. swell
3. sand wash
4. scab

Answer 1

Correct Answer - Option 1 : cold shut

Explanation:

The casting defect and their reasons are mentioned below:

Cold shut: It occurs when two-stream of molten metals approach each other in the mould from opposite directions.

Swell: It is a localized enlargement of casting at its top side and is caused due to pressure of molten metal on soft rammed sand.

Sand wash: It is an irregularity in the surface of the casting resulting from the erosion of the sand mould during pouring and the contour of the erosion is formed in the surface of the final casting.

Scab: It is a hollow cavity on a flat casting surface caused by the liquid metal pressure, which succeeds in pushing back the mould sand at certain places.

 

Casting defects are those characteristics that generate imperfection in a casting exceeding the quality limits imposed by the design or service condition of the casting. As per standard casting defects, they are of seven types:

1. Metallic Projection:

• Mismatch
• Lifts and shifts
• Fins and flash
• Swell

2. Cavities

• Blow-holes
• Pin-holes or gas porosity 

3. Discontinuities

• Hot tears

4. Defective surface

• Fusion and metal penetration
• Hard spots
• Cold shots
• Scabs or washes
• Scar 
• Blister

5. Incomplete castings

• Misrun and cold shut
• Pour short
• Runout

6. Incorrect dimension and shape

• Warping
• The drop

7. Inclusions

• Sponginess or honeycombing