Tailoring flow behavior and heat transfer in tempering channels for high pressure die casting – Analysis of potentials of commercial static mixers and prospects of additive manufacturing

Abstract

High Pressure Die Casting (HPDC) is an economic manufacturing processes for production of complex, multifunctional and thin-walled metal components with near-net-shape geometries. During die filling and subsequent solidification of the component in the die, efficient and robust control of temperature is of utmost importance. This is mostly achieved by fluid-based temperature control systems. Eventually, the heat transfer between the fluid and the die determines total cycle times. In present work the impact of static mixers and most relevant processing conditions is investigated experimentally as well by Computational Fluid Dynamics (CFD) simulation. Static mixer elements are integrated into straight tempering channels to stimulate turbulences of the flowing tempering medium and, eventually, increase the heat transfer coefficient α. In a second step, prospects related to additive manufacturing (AM) of moulds by means of Laser Powder Bed Fusion (PBF-LB) are detailed and discussed. The unprecedented design freedom of AM opens up numerous possibilities for positioning the static mixer elements, as highlighted for helical mixers in tempering channels of HPDC die casting moulds made of AISI H13 (X40CrMoV5-1, 1.2344). Obviously, in recent years AM already has been exploited to establish near-contour temperature control systems in industrial applications, i.e., for conformal cooling. However, the flow-influencing mixing elements investigated in the present work have not been considered so far. As will be highlighted by the results presented, a positive impact on heat transfer and, thus, further increase in terms of the economic efficiency of the HPDC process arises from the concepts introduced.