Which of the following is NOT a source of contraction in a metal casting?

In the context of metal casting, contraction refers to the reduction in volume that occurs as materials change state or cool down. The contraction processes involved during metal casting mainly originate from the molten metal itself and its transition into a solid state.

The correct answer, which states that the contraction of the mold material is NOT a source of contraction relevant to the casting process, is accurate because the mold's primary role is to contain the molten metal and shape it as it solidifies. While mold materials can experience thermal expansion and contraction, these changes do not contribute to the contraction of the cast metal itself.

In contrast, the other factors listed, such as the contraction of molten metal after it is poured, solidification shrinkage during the metal's transformation from liquid to solid, and the cooling of the solidified metal, all play crucial roles in determining the final shape and dimensions of the casting.

Contraction of the molten metal occurs as it cools and solidifies, leading to shrinkage. Solidification shrinkage happens due to the change in internal structure when transitioning from liquid to solid. Cooling of solidified metal results in additional contraction as the metal decreases in temperature. Collectively, these processes emphasize the importance of accounting for contraction in the design and execution of