When it comes to manufacturing, every component needs to meet its exact specifications to create a final product. There are various processes available to make necessary parts unique to a product, but investment casting is one technique that stands above others in many ways.
Investment casting is an old way to form metal using minimal machinery and energy. It is best for creating intricate parts, and it is still beneficial in today’s industrial environment.
This blog will explain why this old-world metal forming technique stands the test of time and how various industries use it today.
What Is Investment Casting?
The metal forming process known as investment casting dates back almost 5,000 years. Other names for this technique include lost-wax casting and precision casting. Manufacturers use this technique to accurately cast metals with a high heat tolerance using a plaster, plastic, or ceramic mold and a wax pattern that melts away.
Investment casting is ideal for creating precise components with unique shapes that require tighter tolerances and better surface finishing.
A Glance into the Investment Casting Processs
The pattern and mold creation process sets investment casting apart from other metal fabrication methods like die and sand casting.
Here is a breakdown of the process:
- A design engine first makes a wax pattern using a metal injection die. The pattern will have all the details for a section or portion of the finished component but with slightly larger dimensions to account for thermal contraction.
- Next, the engineer creates the runner and gating system by connecting multiple patterns to form the final component. Molten metal will flow through the runner system as it fills cavities in the mold, creating a well-balanced casting. Gates are the openings between the runner and the cavity that feeds molten metal into the space.
- Once the entire pattern is complete, it is dipped into a ceramic slurry and covered with sand stucco. The design engineer repeats the dipping process until the shell achieves the appropriate thickness. At this point, the dried shell’s durability is strong enough to withstand the heat from the molten metal. Also, it will retain its shape during the last step.
- The wax melts away under high temperatures, and trace amounts soak into the plaster or ceramic mold. The void left by the melted wax pattern will be filled with an alloy to create a precise metal casting.
How Is Investment Casting Used Today?
This casting process is excellent for creating products and prototypes. It has widespread applications across various industries, primarily the automotive and industrial industries.
So, what is the best metal for casting? Well, how different industries use the castings today depend on the metals they need, but refractory metals with high melting points work best.
Design engineers use this material the most in investment castings. A blend of aluminum, silicon, and magnesium is strong enough to create premium automotive components, but casters also use the alloy for electronics and industrial equipment.
Steel is known for its durability, which is why this variety of metal is a popular choice for various components. Casters use this material to craft everything from auto parts to golf club heads.
Metalworkers turn to titanium alloy when making castings that need to be strong enough not to fracture when it has a crack. For example, golf clubs and marine components are a common choice for titanium castings.
Advantages of Investment Casting
This method is ideal for crafting small, complex geometric shapes that have intricate features with one mold.
Investment casting is highly versatile. Because you can combine multiple wax patterns to create one unique mold, you can configure parts you could not make with a machine or tools, making it a worthwhile alternative to weldments.
Dimensional precision and smooth finishes are other benefits of this casting method. The casters form the ceramic shell around even patterns, leaving behind no parting line because only one mold makes the casting, not two. The result is a smooth finish averaging around a 125 micro finish, but post-process smoothing can achieve a more refined finish, if necessary.
Other advantages of investment casting include:
- Reusable Materials: Design engineers can reuse the melted wax for another pattern. They can also reuse the mold, thanks to its strength.
- Tight Tolerances: Investment casting can have a tolerance of .003″, which is tighter than most casting processes such as die casting.
- Design Capabilities: With investment casting, design engineers can incorporate identifying markers to the casting, such as numbers, logos, and product IDs.
Disadvantages of Investment Casting
Despite the beneficial nature of lost-wax casting, it does have its drawbacks. The most significant disadvantage is the size limitation. Because so few design engineers can produce large parts using this technique, it may not be the best option for a client who needs to fabricate a bulky component.
This process is best for casting small intricate components. Parts exceeding 75 pounds are better suited for other casting methods.
Investment casting shells also have limitations on their size and depth. They cannot be smaller than 1.6mm or deeper than 1.5 times the diameter. If your casting design requires cores and cannot fit these requirements, you may need to seek another process.
This technique is more complicated than other casting processes, and it requires a substantial amount of preparation and specialized equipment. As a result, the upfront cost of investment casting can be more expensive than sand casting or die casting, but the production cost per unit decreases with larger orders.
Start An Investment Casting Project Today With TFG USA
Investment casting may have roots dating back 5,000 years, but it still has beneficial applications in modern society. Throughout the world, industries rely on precision casting to produce intricate components with smooth finishing, unique geometric shapes, and tight tolerances, including the industrial,, automotive, firearm, food processing equipment, and agricultural equipment manufacturing industries.
The Federal Group USA offers superb investment casting services. We use specialized shell making and wax processing equipment to fabricate patterns and cast quality components quickly. If you would like to learn more about our investment casting services and receive a free quote on your upcoming project, contact our team today.