Patent ID: 7234505
Filing Date: 2007-06-26
Classification: B22D,Y10S

Abstract:
1. A process for producing castings of an aluminium alloy, using a pressure casting machine having a pressurised source of substantially molten aluminium alloy and a metal flow system comprising a die or mould assembly defining a die cavity, wherein the process includes the steps of causing the alloy to flow from the source to the die cavity along an alloy flow path defined by a component of the die or mould assembly; causing the alloy, in its flow path along the flow system, to flow through a runner and through an inlet end of a controlled expansion port (CEP); and causing the alloy, in its flow path through the CEP to an outlet end of the CEP, to decrease in flow velocity, whereby the alloy is caused to attain a sufficient flow velocity at the inlet of the CEP, and to undergo a substantial reduction in that flow velocity in its flow through the CEP, such that the alloy attains a viscous or semi-viscous state and retains that state in filling the die cavity, wherein the alloy attains a flow velocity through the CEP inlet which is in excess of 40 m/s and not more than 120 m/s and the alloy flow velocity through the CEP outlet is from 50 to 80% of the alloy flow velocity through the inlet of the CEP.