PURPOSE: To save space and time by breaking the solidified riser at each connection part and separating the riser from the casting in the sand within the casting flask when the casting is solidified, and to easily separate the casting from the runner without deteriorating the working environment.

CONSTITUTION: The riser 5 works as the riser, and at the same time, the runner 3 and the casting 4 are connected 6,7 to each other through the riser 5, and both connection parts 6,7 can be broken and separated at one time by pressing them in the sand 2 within the casting flask 1, leading to extremely easy separation of the runner 2 from the casting 4. In the method of breaking the connection parts when the temperature of the connection parts 6, 7 is 700-800°C, the casting is generally solidified to the degree where the casting is not deformed by the external force in such temperature, and at the same time, the strength is greatly reduced such as the tensile strength at high temperature of gray cast iron, and leading to easy breaking.