Development and Implementation of a Die Thermal Management Model (DTMM)

Abstract

Thermal management in die casting involves controlling heat transfer between the molten metal and the die surface. A cooling system integrated into the die facilitates the rate of heat extraction at the die-molten metal interface. However, non-uniformity of die surface temperature can occur due to the variation in the amount of heat that needs to be extracted from the casting leading to low casting quality. These variations are usually caused by differences in the casted part thicknesses. Therefore, effective die thermal management (DTM) is crucial, as it influences the quality of the final casted component in terms of its final shape, microstructure, and mechanical properties. The main objective of the present research work is to develop a new DTM algorithm that addresses the shortcomings of existing DTM techniques. Initially, the aim is to estimate the rate of heat transfer at the die-metal interface in order to identify locations experiencing the highest heat exposures (i.e., hot spots). Subsequently, a heat balance is used to determine the necessary adjustments to the cooling water flow rates fed into each cooling channel to mange the hot spot and to achieve a more uniform temperature distribution along the die interface. Ultimately, the goal is to develop a die thermal management model (DTMM) that can be used to vary the water flow rate in each cooling channel based on the rate of heat extraction required based on the casted part geometry. The DTMM has developed using inverse heat transfer techniques and validated using data obtained for a set of virtual and real experiments. The data of the virtual experiments were generated using numerical simulations carried out using the computer software Flow3D Cast. The numerical and real experiments were carried out for a gravity-fed die casting process of pure Aluminum in a wedge-shaped mold, which was intentionally selected to reproduce some non-uniformity in the thickness of the casted part. Such non-uniformity was used to assess the effectiveness of the developed DTMM. Simulation results obtained using Flow-3D have been compared with the experimental results in order to assess the predictive capabilities of Flow3D. The DTMM demonstrated a significant reduction in the maximum temperature difference along the die surface, achieving up to 92 % improvement. As a result, the die interface experienced a more uniform heat distribution when variable cooling flow rates were applied, in contrast to constant cooling flow rates.