Complex shapes of aluminum castings are typically manufactured during the short
cycle process known as the high-pressure die casting (HPDC). High productivity is ensured by
introducing die cooling through a system of channels, die inserts or jet coolers. Die cooling can
also effectively help in reducing internal porosity in cast components. Accurate simulations
based on sophisticated numerical models require accurate input data such as material properties,
initial and boundary conditions. Although the heat is dominantly dissipated through die cooling,
indicating the importance of knowing precise thermal boundary conditions, open literature lacks
a detailed information about the spatial distribution of heat transfer coefficient. This study
presents an inverse method to determine accurate heat transfer coefficients of a die insert based
on temperature measurements in multiple points by 0.5 mm K-type thermocouples and a
subsequent solution of the two-dimensional inverse heat conduction problem. The solver was
built in the open-source CFD code OpenFOAM and the free library for nonlinear optimization
NLopt. The results are presented for the commonly used 10 mm die insert with a hemispherical
tip and coolant flow rates ranging from 100 l/h to 200 l/h. Heat transfer coefficients reach values
well above 50 kW/m2K in the hemispherical tip, which is followed by a secondary peak and then
a gradual drop to values around 1 kW/m2K further downstream.