The primary vertical passage through which molten metal travels from the pouring basin down into the mold cavity or runner system. It is usually tapered toward the bottom to choke the flow, keeping the channel full and preventing air from being sucked into the metal stream. A poorly designed downsprue causes turbulence and introduces oxide defects into the casting.
Heard on the job
The metal is dropping too fast, so we need to choke the downsprue more on the next pattern revision.
Also heard as
- downcomer
Do not mix it up with
- Sprue: A sprue can refer to the entire delivery system or the waste metal left inside it, while the downsprue is specifically the vertical pipe.