Improved VDC Casting of Aluminium Alloys through an Understanding of the Surface Properties of the Molten Metal


Article Preview

Vertical direct chill (VDC) casting of aluminium alloys is a mature process that has evolved over many decades through gradual change to both equipment design and casting practice. Today, air-pressurised, continuous lubrication, hot top mould systems with advanced station automation are selected as the process of choice for producing extrusion billet. Specific sets of operating parameters are employed on these stations for each alloy and size combination to produce optimal billet quality. The designs and parameters are largely derived from past experience and accumulated know-how. Recent experimental work at the University of Queensland has concentrated on understanding the way in which the surface properties of liquid aluminium alloys, e.g., surface tension, wetting angle and oxide skin strength, influence the size and shape of the naturally-stable meniscus for a given alloy, temperature and atmosphere. The wide range of alloyand condition-dependent values measured has led to the consideration of how these properties impact the stability of the enforced molten metal meniscus within the hot top mould cavity. The actual shape and position of the enforced meniscus is controlled by parameters such as the upstream conduction distance (UCD) from sub-mould cooling and the molten metal head. The degree of deviation of this actual meniscus from the predicted stable meniscus is considered to be a key driver in surface defect formation. This paper reports on liquid alloy property results and proposes how this knowledge might be used to better design VDC mould systems and casting practices.



Materials Science Forum (Volumes 519-521)

Edited by:

W.J. Poole, M.A. Wells and D.J. Lloyd




J. A. Taylor and I. F. Bainbridge, "Improved VDC Casting of Aluminium Alloys through an Understanding of the Surface Properties of the Molten Metal", Materials Science Forum, Vols. 519-521, pp. 1693-1698, 2006

Online since:

July 2006




[1] B.J. Keene: International Materials Review, Vol. 38, (1993), pp.157-192.

[2] J.P. Anson, R.A.L. Drew and J.E. Gruzleski: Met. Trans. B., Vol. 30B, (1999), pp.1027-1032.

[3] I.F. Bainbridge, J.A. Taylor and A.K. Dahle: Materials Forum, Vol. 28, (2004), pp.1297-1302.

[4] I.F. Bainbridge: PhD thesis, School of Engineering, University of Queensland (2005).

[5] P.W. Baker and J.F. Grandfield: Proc. 7th Australian Asian Pacific Conf. Aluminium Cast House Technology, Hobart, Australia, (TMS, Warrendale, PN, USA, 2001), pp.195-204.

[6] I.F. Bainbridge, J.F. Grandfield and J.A. Taylor: Proc. 9 th Australasian Conf. Aluminium Cast House Technology, Melbourne, Australia, (CSIRO Publishing, Melbourne, 2005), pp.85-92.

[7] S.C. Flood, P.A. Davidson and S. Rogers: Proc. Modelling of Casting, Welding and Advanced Solidification Processes VII, (TMS, Warrendale, PN, USA, 1995), pp.810-808.