The British Steel Casting Research Association has done a lot of research work on the metal penetration of chromite sand. It uses a mold with a protruding cylindrical mud core at the bottom, and air pressure is applied to the top of the molten metal to imitate the pressure of a 6-foot-tall (~1828.8mm) metal. This test shows that the permeation disturbance ability of chromite sand is much better than that of quartz sand and Hao sand. This may be due to the small contact surface between chromite sand and molten metal, and the poor performance of steel when the molten steel contacts the chromite sand. Poor melting characteristics.