Investment casting is one of the best casting options for creating intricate parts. The manufacturing process makes use of a wax pattern coated with a refractory ceramic material, which is allowed to dry and harden.
The wax is melted out and leaves an internal cavity to shape the final product’s geometry.
The application of investment casting is broad due to its unique benefits in industries such as automotive, aerospace, power generation, military firearms, food, oil and gas, commercial, and energy. All these industries make use of metals manufactured with investment casting.
The technique is called investment casting because the workpieces are created around a shelled casting, which will be removed once the workpieces are poured into the mold.
There are several steps involved in designing and creating the desired objects. Well, in this reading, we’ll explore what investment casting is, its applications, diagrams, advantages, disadvantages, and how it works.
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What is Investment Casting?
Investment casting, which is also known as “lost wax” casting, is a method of the precision casting process to manufacture small, complicated parts using almost all alloys.
The process uses the replication of wax patterns to create parts. The term lost-wax casting is the modern way of describing the investment casting process.
The manufacturing technique has been used in various forms for the last 5,000 years. Beeswax was earlier used to form patterns necessary for the casting process.
However, investment casting makes use of more advanced waxes, refractory materials and specialist alloys used for the pattern.
Investment castings are highly in demand due to their ability to produce components with accuracy, repeatability, and versatility, and various metals and high-performance alloys can be used.
Applications of Investment Casting
In the early stage, it was used by ancient Chinese and Egyptian cultures to create artwork. Not until the development of the jet turbine engine at the end of world war II.
Investment casting became an enabling technology in most industries today, and their applications. The casting technique is of high demand due to strength and precision. It is popular in many industries, including
- Aerospace and defense
- Power generation
- Military
- Marine
- Automotive
- Oil and gas
- Space exploration
- Medical/orthopedics
- Agriculture
- Construction
- Commercial and consumer products.
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Diagram of Investment Casting
How Does Investment Casting Work?
Investment casting involves creating a desired object through several steps, including creating a wax pattern, arranging the patterns in multiple wax patterns, and creating a gate device for metal or material to pass through.
The tree-like arrangement of the wax patterns allows for multiple items in a single set.
A shelled casting is then added to the tree, dipped in ceramic slurry and fine sand. The mold is allowed to dry before proceeding to handle the casting stress.
The wax is removed by heating it in an oven or steam, and the mold is placed upside down to allow liquid wax to flow out, creating new wax patterns.
Molten metal is poured into the shell, and the material remains in the casting until it cools and solidifies. We remove the shelled casting, leaving the original tree intact.
We carefully cut off the objects, inspecting them for imperfections. These can be sanded, coated, smoothed, or machined to achieve the desired object. Learn more about investment casting and its process.
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Things to Considered When Choosing this Casting Process
It is important to know the things it can offer before choosing it. These factors will guide the production process if the job truly aligns with the casting process. factors consider include
Tooling cost: Understanding and calculating the tooling cost is crucial before choosing any casting process. For example, casting low-quantity items in investment casting will be more expensive. Therefore, it is important to take this into account when pursuing a long-term investment. Payment for castings should be considered when determining if this casting offers greater value.
Size limitations: suitability for producing small parts. Big parts should not be formed in this process, unlike sand casting, which is suitable for large parts. Items with small sizes and intricate shapes should be cast during this process.
Very small structures: this process is suitable for making thin-walled applications. However, incorporating cores can be difficult and challenging. Typically, a core cannot be smaller than 1/16 (1.6mm) or deeper than 1.5 times its diameter.
Timing: The time it takes to produce items should also be taken into account in investment casting. the multi-step method is more time-consuming.
Advantages of Investment Casting
Below are the benefits of investment casting:
High-Quality Finish: Investment casting can produce parts 99.5% precisely while maintaining an excellent surface finish. This technique greatly reduced the need for additional surface finishing.
Complex Shape: With investment casting, complex items can be produced. Majority of the items produced by this casting technique are often rejected by other casting methods.
Tight Tolerances: Investment castings produce parts accurately with tighter tolerances, which is why they are called precision castings.
Material Diversity: With investment casting, it is possible to cast almost any kind of metal and alloy of varying melting points. for instance, aluminum, steel, cobalt, brass, etc.
Material Recycling: You can recycle the mold material and reuse it for the next casting cycle. This procedure will help save cost and time.
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Disadvantages of Investment Casting
Below are the limitations of investment casting:
Complex Process: Investment casting is a very complex process that will require a skilled performer to perform it.
High Cost: The process will cost much, which is why it is often done when castings are needed in bulk. It is not suitable for castings needed in small quantities.
Time-Consuming: Investment casting involves a lot of steps, making each casting cycle longer to accomplish.