Lost Wax Casting:
Lost wax casting is also called as investment casting and is one of the oldest technique carried out to obtain precision casting.
Today lost wax casting is widely used in each and every sector of casting so as to reduce machining cost and obtain fine surface finish.
What is The Process of Lost Wax Casting?
In lost – wax casting process wax pattern is coated with refractory ceramic material and ceramic material is hardened its internal geometry which takes the shape of the casting after that wax is melted out and molten metal is poured in the cavity.
The lost wax casting is divided in below mentioned departments for process control of castings.
- Die/Mold making
- Wax Pattern making
- Wax pattern tree
- Shell building
- Shell firing
- Refractory ceramic removal
Die/Mold Making:-For making die it is very important to get perfect drawings of the specimen to get perfect die cavity as per norms
Wax Pattern Making :-After we get a correct die with perfect dimensions wax is injected in the die making is the replica of the final piece which is going to be casted.
Wax Pattern Tree:- Wax patterns dimensions are properly checked using Vernier caliper and are mounted on runner systems using sticky wax and finally it looks like wax pattern tree.
Shell Building :- After the wax pattern are completely stick on the runners they are properly inspected and then are dipped in refractory ceramic material and coated with zircon sand kept for drying and after a cycle of dipping coating and drying a thick layer is formed on the wax patterns which is called ceramic shell
Dewaxing:-After the shell is fully dried they are placed on shell stand and inserted in autoclave dewaxing machine and the wax is taken out from the shell at about 175°C which leaves the same cavity as the wax pattern inside the shell.
Shell Firing :- When the wax is removed from the shell. shell firing is done to remove the remains of the wax and increase the permeability of the shell.
Casting:- As the shell achieves a certain temperature in shell firing furnace the shell is taken out and placed on a sand bed and then the metal is poured in the cavity of the shell.
Refractory Ceramic Removal :- As the metal is cooled down after pouring in shell the shell is set to knocking machine to remove the refractory ceramic and get the final casted parts
Finishing :- the final castings are separated from the runner bars and further taken in machining department where finishing work like fettling, finishing is done of the casted parts. If needed certain heat treatments and surface treatments are given.
What are the Other Uses of Lost Wax Investment Casting Process?
Foundry-men and artists to make intricate sculptures, ornaments and automobiles widely uses the lost-wax casting process from decades. This process is also used for making casting brooches, jewelry, buckles and other small parts used in various industries.
What are the Advantages of the Lost wax Casting Process?
Despite modern ways of casting, foundry-men and artists still prefer the traditional methods of casting. Some of the advantages include –
- The lost-wax casting process can be used on any material that can melt burn and evaporate to leave behind a mould cavity.
- The duplicate model will reproduce even minute details of the original sculpture.
- Allows for unique shapes of casting that would be impossible in other methods.
- Near net shape castings are produced with high productivity and competitive price.
Hence, the lost wax investment casting process is a seasoned method for the reproduction of various objects.
However, the procedure does have its disadvantages such as the initial cost, need for large machinery and the particularity of holes in the mould. Therefore, it is important to look for expertise, design, performance and cost to get the best quality at the best price.