The four terms
Investment casting is the standard English engineering term. "To invest" means to surround: the pattern is invested with refractory material. The term describes the mould-making principle and says nothing about the pattern material, although wax is by far the most common.
Lost-wax casting names the pattern instead of the mould: the wax is lost when it is melted out. It is the older, more descriptive term, widely used in art casting and jewellery and common in general language. In industrial use it means the same process as investment casting when the pattern is wax. Patterns printed in polymers or resins are, strictly speaking, lost-pattern rather than lost-wax.
Precision casting describes a result rather than a method. In German (Feinguss), French (fonderie de précision) and Dutch (precisiegieten) the corresponding word is the normal name for investment casting. In English, however, "precision casting" is sometimes applied more loosely to other accurate casting processes such as ceramic mould or plaster mould casting. On drawings and in contracts, "investment casting" is therefore the less ambiguous English term.
Ceramic shell casting identifies the mould type used by almost all industrial investment foundries today: a thin shell built up by repeated dipping and stuccoing. It distinguishes the method from the older solid mould (block mould) variant, in which the pattern cluster is placed in a flask and embedded in a refractory slurry; that variant survives in jewellery, dental and some aluminium and prototype casting.
Terms that are easily confused
- Shell moulding (Croning process) uses resin-bonded sand formed against a heated metal pattern. Despite the similar name it is a sand-casting process with a parting line and is unrelated to ceramic shell investment casting.
- Lost foam casting also uses an expendable pattern, but the polystyrene pattern is left in unbonded sand and vaporised by the metal.
- Die casting uses permanent metal moulds; in some languages the similarity of everyday words leads to confusion with investment casting.
Terms in four languages
| English | German | French | Dutch |
|---|---|---|---|
| investment casting | Feinguss | fonderie de précision | precisiegieten |
| lost-wax process | Wachsausschmelzverfahren | procédé à la cire perdue | verlorenwasmethode |
| ceramic shell | Keramikschale | carapace céramique | keramische schaal |
| investment casting (part) | Feingussteil | pièce de fonderie de précision | precisiegietstuk |
More terms are listed in the glossary.
Why the distinction matters
The name alone does not define capability. Two suppliers that both offer "precision casting" may differ in the alloys they melt, whether they pour in air or under vacuum, the size of part they can handle and the tolerances they hold. Requirements should therefore be stated explicitly: material specification, tolerance standard and grade, surface and inspection requirements.