Papers by Author: Thang Nguyen

Abstract: Globalisation of supply chains for the automotive industry has made it increasingly difficult for developed economies to compete on price alone. In Australia, Nissan Casting has adopted technologies to reduce tooling costs and improve productivity of the die casting machines which use vacuum. Nissan Casting was experiencing cracking of their dies which extended into cooling lines, causing porosity outbreaks and shortened die life. CAST developed a repair technology called CASTrepair™ which is a relatively quick, simple and inexpensive repair technique for cracked cooling lines in HPDC dies. Also Nissan Casting is an extensive user of vacuum and a major issue was identified as unscheduled machine stoppages caused by aluminium blockages in the vacuum valves. The valves were of the mechanical shut off type and when they failed to shut off quickly enough aluminium entered the valve which then had to be changed. CAST developed CASTvac™ which is essentially a three dimensional chill vent with no moving parts required as a means to stop the aluminium entering the vacuum system. CASTvac™ has proven to be very reliable in production and has significantly reduced downtimes and toolroom maintenance at Nissan Casting. These two technologies, CASTrepair™ and CASTvac™, will be explained in detail with the latest developments in the technologies and associated benefits of their adoption.

Abstract: This work aims to develop flow and thermal control methods for the high pressure die casting (HPDC) of very thin-walled aluminium components where thicknesses are predominantly less than 1 mm. One specific aim includes developing advanced modelling capability using CFD software to predict the complex structure of the metal flow in the die and the casting solidification. The modelling based on FLOW-3D started initially with a fluidity die study to establish several key parameters in HPDC modelling through experimental validation. A new test casting geometry has been designed in the form of a shallow tray with other features such as changes in curvature, fins and bosses. The casting thickness can be made variable in the die. The experimental work was conducted on a 250-tonne HPDC machine. Initial models of molten metal flow in the die cavity based on a runner design for casting thicknesses between 1.5 mm and 1 mm are presented. The detailed model required a very large mesh of very small elements, and more accurate physical parameters which may not have been previously available.