Electric powertrain components such as the electric motor or power electronics usually require fluid-based thermal management integrated into their housing. Double-shell designs or integrated cooling tubes are commonly used for die-cast components to implement such solutions. Thin-walled aluminium tubes improve heat transfer, but usually only withstand high pressure die casting conditions with the help of stabilising fillers that are removed after casting [1]. An alternative approach is to realise pipes with integrated cooling channels via metal additive manufacturing (AM) processes such as Laser Powder Bed Fusion (LPBF). The advantages of this process range from the higher strength of LPBF materials to the well-known geometric freedom of AM techniques: The latter can be used to incorporate internal structures into the cooling channels that provide stabilisation during casting, but at the same time lead to an improved heat transfer from the channel wall to the coolant with low drag.

In this study, different cooling channel designs are compared in terms of (a) their resistance to the casting conditions, (b) the cooling capability and (c) the flow resistance caused by the internal structures. The investigations rely on both simulation and experimental approaches for all aspects covered, using Altair's AcuSolveTM for CFD simulations of flow and heat transfer, MAGMASOFT® for casting simulation and Abaqus for evaluating the stability of the cooling channels. Experimentally determined temperature-dependent material property data for LPBF-processed AlSi10Mg in stress-relieved [2] and T5 states from room temperature to 450°C are used for this purpose in combination with thermal and mechanical stress data derived from casting as well as FEM simulation. The casting experiments are carried out on Fraunhofer IFAM’s Bühler SC/N 66 high pressure die casting machine using a test mould producing a plate geometry with integrated straight tubes. Such inserts with different internal structures were additively manufactured by Fraunhofer IAPT on an EOS M290 system. The cast part can be connected to a special test rig for measuring heat transfer between casting and tube. The simulated data are compared with the experimental results with the aim of creating a validated basis for the design and dimensioning of future series products.