Project ForgeManufacturing Engineering
Metal Casting
GATE 2019
Medium
Match the sand mold casting defects with their respective causes. Defects: P=Blow hole, Q=Misrun, R=Hot tearing, S=Wash. Causes: 1=Poor collapsibility, 2=Mold erosion, 3=Poor permeability, 4=Insufficient fluidity.
- AP-4, Q-3, R-1, S-2
- BP-3, Q-4, R-2, S-1
- CP-2, Q-4, R-1, S-3
- P-3, Q-4, R-1, S-2
Explanation
Blow holes form from trapped gas due to poor mold permeability (P-3). Misrun happens when molten metal solidifies before filling the mold, due to insufficient fluidity (Q-4). Hot tearing occurs when a rigid mold resists the casting's contraction during cooling, i.e. poor collapsibility (R-1). Wash is surface erosion of the mold by the metal stream (S-2).
Source: GATE ME 2019 Session 1 (Set 1) (2019)
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