Lost Wax Castings
Lost wax casting is the traditional name for investment casting: a wax replica of the part is coated in ceramic, the wax is melted away, and metal is poured into the resulting mould. It gives precise, detailed castings in steel, stainless steel and non-ferrous alloys.
What it is
The process takes its name from the wax pattern that is "lost" when the ceramic shell is heated. Each casting needs a new wax pattern, produced from a reusable die.
Two shell systems are common: water-glass (sodium silicate) shells, economical for larger carbon-steel parts, and silica-sol shells, which give better finish and accuracy for stainless steel and precision parts.
Typical applications
- Valve and pipe fittings
- Hardware and marine fittings
- Textile and packaging machine parts
- Automotive components
- Art and decorative castings
Suitable materials
- Stainless steel
- Carbon and low-alloy steel
- Brass and bronze
- Aluminium
- Special alloys
Points to consider
- Silica-sol process gives the best finish and accuracy; water glass is cheaper for larger, less critical parts.
- Combine several machined parts into one casting to save assembly.
- Provide the finished drawing so the casting can be designed with minimal machining.
- Allow sample approval before production runs.
Frequently asked questions
What is silica sol investment casting?
A lost-wax process using a silica-sol bonded ceramic shell, giving better surface finish and accuracy, especially for stainless steel.
How many parts are economical by lost wax casting?
Typically from a few hundred parts a year, as the wax die cost is spread over the volume.
Can lost wax castings replace machined parts?
Often yes. Complex machined parts can become near-net castings with only critical features machined.