Heat transfer at the glass-mold interface

Abstract

The nature of the glass-to-mold-metal interface and its influence upon the interfacial heat transfer is discussed. Initially the glass-to-mold separation is approximately 2,5 ∙ 10^-5 cm, increasing to approximately 0,004 cm after more than one second of dwell time. The initial heat transfer is ascribed to free-molecule conduction in the air gap, and undergoes a transition to ordinary bulk conduction as the gap widens. Both the magnitude and time dependent nature of the heat transfer coefficient are explained. The same general considerations should apply in any process involving the forming of a hot deformable material in a solid mold.