What is Lost Wax Casting?
The lost-wax casting process, also called investment casting is a method of metal casting in which molten metal is poured into a mold that has been created by means of a wax model. Once the mold is made, the wax model is melted and drained away.
Lost wax casting is an ancient process in which the wax pattern gets melted during the molding process, hence the name lost wax is given to this process.
Intricate designing of sculptures, ornaments, and automobiles can be captured only by this process.
Process:
Traditionally, in lost-wax casting, wax patterns were made by hand for every single piece of mold. But today, one pattern can be used to make multiple patterns even though the pattern is lost or melted during the process. Solid or hollow patterns can be used for molding purposes.
There are two ways of making the pattern, either by directly making it from wax or making the model in materials like clay and then making a wax copy out of it.
Molten wax is poured into the mold to the desired thickness and kept upside down to cool.
When the wax is cooled the wax pattern is removed from the mold and improved on to give a perfect finish.
Once the wax pattern is ready sprues and gates of wax are attached for pouring the molten metal.
The pattern is surrounded with materials that will hold on to the pattern when it is wet.
Now a coarser material is added to make a strong mold in which the metal can be poured and solidifies.
The mold is placed in the kiln, fixed in place with flasks.
This mold in the kiln is heated until the wax is melted.
Now there is an emptiness in the place where the wax existed.
The molten metal like bronze, or gold takes its place.
When the metal cools, the mold is broken away or sandblasted to remove the cast.
Applications:
Lost-wax process is being used from time immemorial for casting jewelry and small parts.
This process is also used to manufacture fashion accessories like brooches and buckles.
Some automobile manufacturers use a lost-foam technique to make engine blocks.
Now days lost wax process is used for dental restoration, fine jewelry, sculptures, etc.
Silver, gold, aluminum, brass, or bronze are cast with this method.
Lost wax Casting Advantages:
The lost-wax process can be used with any material that can burn, melt, or evaporate to leave a mold cavity
Faithfully replicated every detail of the original wax
Allows shaping of castings that would be impossible in other methods.
