The gating system is the general name of the channels through which the liquid metal in the sand mold flows into the mold cavity. It is composed of gating cup (outer runner), sprue, sprue nest, transverse runner and inner runner. Whether the gating system is designed correctly or not has a great impact on the quality of sand castings. About 30% of thewaste is caused by the improper gating system.
- The position, direction and number of the internal runner determined shall conform to the solidification principle or feeding method of sand casting
- Fill the cavity within the specified pouring time.
- Make the liquid metal flow stable and avoid serious turbulence. Prevent from getting involved, absorbing gas and excessive oxidation of metal
- It has good slag resistance.
- The linear velocity of molten metal entering the mold cavity shall not be too high to avoid splashing and scouring the mold wall or sand core
- Ensure that the metal level in the mold has enough rising speed to avoid sand inclusion, scab, cold shut and other defects
- The metal consumption of the gating system is small and easy to clean.
After spheroidization and inoculation treatment, the temperature of nodular cast iron liquid drops a lot, and it is easy to produce oxidation and dross. The pouring system is required to fill the mold quickly with large flow, and has a smooth flow and better slag retention than the gray cast iron liquid.