A Model to Predict the Heat Transfer Coefficient at the Casting-Die Interface for the High Pressure Die Casting Process

A model is presented for the prediction of the heat transfer coefficient (HTC) at the casting-die interface as a function of time for the high pressure die casting process. Contact geometry and interface characteristics are included in the model through die surface roughness, the mean trapped air layer between the casting and the die, the parameters of area density and the radius of contact spots. The density and the radius of contact spots are integrated into a classical thermal flux tube theory in order to calculate HTC at the casting-die interface. The time dependence of the HTC is derived in terms of the degradation of contact between the casting and the die that occurs during solidification. The calculated HTC is found to agree well with the experimentally determined results for different casting conditions. The presented model provides a valuable tool to predict the effect of various casting process parameters, die surface roughness, casting quality and thickness on the HTC during the high pressure die casting process

A predictive model for the thermal contact resistance at liquid-solid interfaces: analytical developments and validation

An analytical model has been developed to quantify and predict the Thermal Contact Resistance (TCR) at the liquid-solid interface. Contact topography and interface characteristics are included in the model through the inclusion of solid surface roughness parameters and the mean trapped air layer at the interface. In liquid-solid contact, air is often entrapped and compressed inside the microcavities of the solid surface roughness. The mean trapped air layer is determined from the mechanisms of contact at the liquid-solid interface. The proposed models determine the radius and the density of the microcontact points for a given set of contact conditions. The density and the radius of contact spots have been integrated into a classical thermal flux tube theory in order to calculate the TCR at a liquid-solid interface. The models have been applied to the casting-die interface in High Pressure Die Casting. The calculated TCR is found to agree with the experimentally determined results

Bioresource Technology 100 (2009) 3740–3744 Contents lists available at ScienceDirect

journal homepage: www.elsevier.com/locate/biortech Energy valorization of industrial biomass: Using a batch frying proces

Heat transfer at the casting/die interface in high pressure die casting - experimental results and contribution to modelling

The present paper deals with a new measurement method to determine the heat transfer coefficient and the heat flux density at the interface between a casting and its die. This method and the related "Heat Transfer Gauge" were developed together as a cooperative project between CAST (Australia) and CROMeP (France). The device enables the determination of the heat transfer coefficient in an industrial casting machine. Several campaigns with High Pressure Die Casting machines and Gravity Die Casting machine have already taken place in Australia and in Europe, both in research laboratories and on commercially-run casting machines. In this paper we present results from a measurement campaign with a thoroughly instrumented HPDC die machine located at CSIRO in Melbourne. The influence of piston velocity, intensification pressure and various other process parameters on the heat transfer are studied. A model is being developed to explain the evolution of thermal resistance at the casting/die interface, before the formation of a complete air gap. Its first stages are explained here

Interfacial heat transfer during die casting of an Al-Si-Cu alloy

The relationship between in-cavity pressure, heat flux, and heat-transfer coefficient during high-pressure die casting of an Al-9 pct Si-3 pct Cu alloy was investigated. Detailed measurements were performed using infrared probes and thermocouple arrays that accurately determine both casting and die surface temperatures during the pressure die casting of an aluminum A380 alloy. Concurrent in-cavity pressure measurements were also performed. These measurements enabled the correlation between in-cavity pressure and accurate heat-transfer coefficients in high-pressure die-casting operations