Abstract
The back pressure within the mold cavity during centrifugal casting of mercury was measured using a pressure miniature semiconductor directly inserted into the cavity.The obtained results were as follows:(1)The measured values of the back pressure almost agreed with the calculated values of the pressure at the sprue end that were obtained by applying pressure equation.(2)When sprues were more than 1.5mm in diameter, gas was intermittently exhausted through the sprue and the back pressure increased fluctuatingly.(3)Direct-type air vent as thin as 0.5mm in diameter effectively decreased back pressure and casting time.(4)Effect of attachment of the blind-type air vent on the back pressure was negligible.However, when the area of the vent was enlarged to more than 17% of the surface area of mold cavity, casting time decreased to some extent.(5)Thinning the bottom of investment in casting ring from 12 to 6mm had no effect upon both the back pressure and casting time.
