ReplicastÂ® is a novel moulding and casting process, developed by Cti, which allows users to cut costs and waste, meet demand for tailor made castings and improve quality and dimensional accuracy at the same time.
The process can be used to make high integrity castings, with improved machinability and an excellent surface finish, weighing from a few grams, up to 3.5 tonnes.
Our technology replaces conventional wooden patterns with dimensionally precise replicas made from expanded polystyrene, which are either cut from solid blocks by a CNC machine or made by injection moulding.
More complex shapes can be made by gluing different polystyrene parts together and, once the polystyrene replica is complete, it is dipped several times in a special slurry and different grades of ceramic to create a solid, ceramic shell
The shell is significantly thinner than a traditional investment casting shell but with the same excellent internal surface finish.
Shells are fired, removing the foam, put in casting boxes and surrounded with refractory sand. The sand is compacted on a vibrating table before a partial vacuum is applied to the sand to create a firm support for the shell, after which molten metal is poured in.
Using inert ceramic shells reduces the possibility of hydrogen defects, which can be a problem with many high alloy steels and Nickel based alloys.
Meanwhile, the use of ReplicastÂ® techniques to make larger polystyrene replicas and ceramic shells â€“ a process which has been dubbed MEGAshellÂ® â€“ allows far larger investment castings to be made than was ever possible before.