Experimental study on the heat transfer behavior and contact pressure at the casting-mold interface in squeeze casting of aluminum alloy

Abstract

The present paper focuses on the heat transfer and contact pressure at the casting-die interface in squeeze casting process. Experiments were conducted and a “plate shape” was used to cast aluminum alloy A356 in H13 steel die. Based on the temperature measurements inside the die, the interfacial heat transfer coefficient (IHTC) at the metal-die interface was determined by applying an inverse approach. The pressure at the metal-die interface was measured by using Kistler pressure transducer. The acquired data were processed by a low pass filtering method based on Fast Fourier Transform (FFT). Besides, a set of methods was set up to verify the computer program for the inverse model. The results show that the pressure at the casting-die interface and the IHTC rose to the peak value almost simultaneously as soon as the pressure was applied by the press. The higher the applied pressure, the higher the peak value of the IHTC and the pressure at the casting-die interface. It was a pressure maintaining stage immediately after the pressure was applied. During this stage, the pressure at the casting-die interface decreased immediately after it reached the peak value. The IHTC sharply dropped at the beginning. Then, the decrease rate of the IHTC became lower and lower. Besides, the IHTC of the cases with pressure applied was much higher than those without pressure applied. It indicates that the applied pressure greatly improved the contact status of casting and die surfaces and reduced the thermal resistance between the two surfaces. The IHTC profiles of the cases with the pressures 23MPa and 46MPa applied did not make much difference, however, when the applied pressure reached 70MPa, the influence of the pressure at the casting-die interface on the IHTC became very remarkable.