Numerical optimization of conformal cooling channels for thermal distribution and stress characterization in additively manufactured high pressure die casting die

Abstract

The durability and efficiency of High Pressure Die Casting (HPDC) dies, particularly those with Conformal Cooling Channels (CCC) fabricated via Laser Powder Bed Fusion (LPBF), are essential for enhancing operational performance. The impact of the shape and location of CCC on the die insert performance has emerged as a significant issue, affecting die reliability. Using Computational Fluid Dynamics (CFD) simulations, this study developed a predictive model that effectively identified regions susceptible to conformal cooling effects, demonstrating the impact of CCC on temperature distribution, thermal stress concentration, water vaporization, and crack failure, closely aligning with observed conditions. Vapor generation was observed at CCC bends due to flow separation caused by abrupt changes in flow direction and velocity. The corrosion grooves act as initiation points for crack formation on the CCC wall. Pores formed along molten pool boundaries during LPBF. Three alternative CCC geometries—(a) increased-diameter CCC, (b) single-directional spiral CCC, and (c) bi-directional half pitch spiral CCC—were analyzed. The increased-diameter CCC improved cooling efficiency but exhibited greater thermal gradients and stress. Compared to the original single loop CCC, the spiral CCC design enhanced cooling performance due to its closer distance to the die insert surface and higher surface area. These improvements resulted in smaller thermal gradients and more uniform stress distribution for the spiral CCC. Failure life analysis revealed that spiral CCC geometries, especially bi-directional spirals, minimized Von-Mises and tensile stress, reduced vapor formation and improved structural integrity.