Topic: Manufacturing Engineering
Riser is designed so as to
- A. Freeze after the casting freezes
- B. Freeze before the casting freezes
- C. Freeze at the same time as the casting
- D. Minimize the time of pouring
Answer: A. Freeze after the casting freezes
Explanation: A riser is a reservoir of molten metal provided in the casting so that hot metal can flow back into the mould cavity when there is a reduction in volume (shrinkage) during solidification. Therefore, it must be designed to freeze after the main casting freezes.