Vacuum Casting

Abstract

With a view to improve the quality of black heart malleable cast iron cast in green sand mould, the foundry experiment is attempted under superintend by Dr. Keikichi Ebihara, inventor of the vacuum casting method. In practice, the amount of metal to be treated each time in vacuum tank is 400kg, treating time is 2 minutes and vacuum gauge shows the degree of vacuum from 2 to 70 mmHg during treating. The results of experiments can be summed up as follows : (1) From 20 to 50% of involved gas in metal is lost, -and consequently degasing, the original purpose of the vacuum casting method, is achieved. (2) In case of green sand mould casting, internal shrinkage decreases but external shrinkage increases. So, it is not expected that riser of castig becomes smaller. (3) Graphitization of white iron is prevented. This will be due to the fact that graphite nodules decrease. © 1958, The Vacuum Society of Japan. All rights reserved.