GB1199673A - Method of Casting a Light Metal - Google Patents

Abstract

1,199,673. Casting processes; making cores. FORD MOTOR CO. Ltd. 20 April, 1968, No. 18785/68. Heading B3F. A light metal, e.g. aluminium article is pressure cast using a ceramic core that has an undercut portion and is breakable to permit removal from the mould after pouring. The core 23 is moulded in a two-part core-box 1 having a plug 22. A metallic spigot 15 surrounds the plug 22 and is incorporated in the core during moulding. The core moulding material is preferably de-aerated friable aluminium silicate which is self-setting. After removal from the mould the core on spigot 15 is fired at 1000‹ C. The spigot has been previously coated with wax or polyvinyl acetate which melts on firing to compensate for the different thermal expansion of ceramic and metal. In Fig. 2, an A1 piston is cast in a two-part mould 29 using the above prepared ceramic core. Molten Al is poured under pressure and gases produced are withdrawn from the mould through the central bore of the spigot via ceramic filled passages 19 (Fig. 1). After solidification, gudgeon 33 and crown 32 cores are removed and the mould 29 opened. The cast cylinder is gripped and the spigot 15 pulled away therefrom. In so doing, projections 34 on the spigot 15 break up the ceramic core part 25 (Fig. 1).