A parametric study of the heat absorption capacity of metallic moulds-fundamental patterns of its time variation

The capacity of a metallic mould to absorb heat from the solidifying casting plays a key role in controlling the metallurgical, technological and mechanical properties of the casting. Therefore, the main objective of the present paper is to reveal the nature of the mould cooling capacity-time history and to establish a map for the fundamental patterns of this relationship. The extent of the mutual interactions among the principal variables is also examined. The analysis of the present work is confined to a spherical mould of uniform wall thickness to simulate a unidirectional heat flow. The solution of the problem is obtained through finite element approximation. An approximate analytical solution, based on the heat balance integral method, is developed to extend the fundamental solution obtained in this study to the case of transient boundary condition. Application of this analytical development is demonstrated using experimental data. Analysis of the results indicated that the time variation of the mould cooling capacity follows one of two distinctive patterns depending on the combination of govering variables. An unexpected behaviour has been observed; the negative effect of Biot modulus under conditions of no preheat. The effects of various governing variables on the mould cooling capacity have been discussed and summarised.