Moulding involves taking an impression of the pattern in sand which is held together with a self-setting binder, added at a rate of around 1.5%.
To facilitate the extraction of the pattern from the mould, complex shapes are often moulded in many different pieces called cores which are then assembled into the mould cavity upon mould closure.
Some castings will also require different moulding media (sand or ceramic) and exothermic sleeves may be added to alter the thermal conductivity of the mould and ensure a sound casting. Once striped from the pattern the mould is coated with a refractory paint to improve the surface finish of the completed casting.
The two halves of the mould are located together with male and female locaters for accurate alignment of the mould. At this time cores and ceramic foam filters as required are placed into the mould.
Moulds are then clamped or weighed down to compensate for the high hydraulic pressures generated during the pouring process.
Austral Alloys employs state of the art cold box (alkaline phenolic bonded) or heat setting (resin coated) binder systems.