Mathematical modelling of air evacuation in die casting process via CASTvac and other venting devices

Abstract

Air venting in the die casting process has been an issue since its inception. A mathematical model that predicts the venting efficiency via different devices, including a new technology known as CASTvac, is presented. This model offers an advantage over other models reported in the literature in that it includes air leakage through die parting faces and the rates of volume compression due to a rapid change of plunger speed. The model has been verified and has predicted that (a) a majority of air is removed during the first stage of injection, in the case of atmospheric venting either using a conventional chill vent or CASTvac; (b) the duration of vacuum application is critical for a simple vacuum system due to die leakage; and (c) CASTvac used as a vent can achieve nearly the same evacuation efficiency as the best simple vacuum system.