Determination of effective riser sleeve thermophysical properties for simulation and analysis of riser sleeve performance

The usage of riser sleeves is ubiquitous within the metal casting industry. Despite the heavy usage of sleeves, there is little literature discussing their thermophysical properties. In this study, riser sleeve thermophysical properties for simulation are developed using an inverse modeling technique. Casting experiments using riser sleeves are performed in order to measure temperatures. Simulations are performed to replicate the experiments. Riser sleeve thermophysical properties are iteratively modified until agreement is achieved between the simulation and the measured data. These finalized properties can be used to effectively predict and therefore optimize the solidification behavior of a given casting. Analyses of sleeve performance are carried out using the developed properties. The modulus extension factor (MEF) is used to quantify sleeve performance and is determined for all riser sleeve materials studied here. A sleeve material’s effects on casting yield are shown to depend only on the MEF and therefore a sleeve’s exothermic or insulating properties serve only to increase the overall quality of the sleeve, expressed by the MEF, and do not independently affect the casting yield at any casting size studied here. Riser sleeves are found to substantially increase the maximum achievable yield for chunky castings but rangy castings only experience small increases in yield due to sleeve usage. Riser sleeve thickness is shown to be extremely influential on casting yield. By observing sleeve thickness effects on the casting yield, optimum sleeve thicknesses for chunky and rangy castings are discerned. An effective lower threshold sleeve thickness is also described.