Printing a mould can mean four different things, and confusing them wastes a lot of time. You can print a pattern that a mould is made from, print the sand mould itself, print a tool for casting resin or silicone, or print an insert for injection moulding. Each has different requirements and different limits.
Printed patterns for casting
The most established use. A printed pattern replaces a machined or hand made one for sand casting, and a printed wax or castable resin pattern replaces an injection moulded wax for investment casting. The pattern must burn out or be removed cleanly, which is why castable resins and printed waxes are formulated specifically for it, and an ordinary printed part will ruin an investment shell.
Printed sand moulds
Binder jetting into foundry sand prints the mould and cores directly, with no pattern at all. That removes the pattern making step entirely, allows core geometry no pattern could withdraw from, and turns a casting programme's lead time from weeks into days. It is a production process in its own right rather than only a prototyping route.
Printed tools for casting resin and silicone
A printed tool can cast urethane, epoxy or silicone directly, provided the printed material releases and survives the exotherm. Resin printed tools give a good surface; filament printed tools show layer lines in every part. Release agents matter more than usual, and a tool that bonds to the first casting is a tool you print again.
Printed injection mould inserts
High temperature resin inserts run tens of shots for bridging and prototyping. Printed metal inserts with conformal cooling are a production optimisation on cycle time. These are the two ends of a spectrum that share a name, and expecting production life from a resin insert is the usual disappointment.
Questions people ask about 3d printed molds for casting
Can you 3D print a mould?
Yes, in four different senses: a pattern to make a mould from, the sand mould itself, a tool for casting resin or silicone, or an insert for injection moulding.
What is a printed sand mould?
A foundry mould and its cores printed directly by binder jetting into sand, removing the pattern making step and allowing core geometry no pattern could withdraw from.
Can a printed part be used for investment casting?
Only if it is printed in a castable resin or wax formulated to burn out cleanly. An ordinary printed part leaves ash and ruins the shell.
How many casts will a printed tool give?
It depends entirely on the material and the casting resin. Resin printed tools give a modest number before the surface degrades, and heat from the exotherm shortens that.