The Ins and Outs of Investment Casting
The casting process or method you choose depends on various factors such as cost, feasibility to manufacture, and the required design.
Investment casting is often chosen because it produces more intricate and precise parts.
Additionally, the process does not require machining, therefore reducing costs and time.
These and other benefits make investment casting one of the most preferred casting techniques used to make metal components.
This post outlines everything you need to know about investment casting.
The aim is to help you understand what investment casting is?
What are the applications of investment casting? What about the advantages and disadvantages?
Read on.
Contents
What Is Investment Casting?
Investment casting is a casting technique used to make metal components.
However, this method differs from other processes since it uses patterns or molds covered in a ceramic slurry to shape the parts.
Investment casting is also called lost wax casting or precision casting.
Investment casting is an age-old casting technique.
However, modern-day manufacturers use 3D investment casting prints to minimize costs and time when manufacturing more intricate parts.
The method is often more suitable for industrial applications that require precision on small-scale production of parts or when the timelines are tight.
What is the Investment casting process?
Many people want to know how investment casting works.
In a nutshell, the process involves using a mold to design components. The entire process can be broken down as indicated below:
Step 1: Pattern Creation
The first step involves making patterns from wax or plastic.
In this phase, a metal injection die is used to create the desired pattern.
Step 2: Pattern Assembly
After creating the pattern, it is then assembled to design a gate and a delivery channel with the tree. Many patterns can be assembled with a single tree depending on the size and shape of the desired product.
Step 3: Mold Shell
After assembly, the pattern is dipped in the ceramic slurry before giving it a sand cover and left to dry.
The dried shell is often strong enough to hold the metal when casting is done.
Step 4: Removing The Wax
The wax is removed in a steam autoclave. The remaining wax is removed in a furnace. After removing the wax, a cavity is left with the desired shape.
Step 5: Melting And Casting
The cavity created (mold) is filled with molten metal and left to cool.
Step 6: Final Touches
After the mold is allowed to cool, the shell is broken to remove the final product. In most cases, the item is sandblasted, ground, and machined to give it the required dimensions.
Which Metals Are Used In Investment Casting?
The process tends to be more versatile, meaning multiple metals can manufacture products with high precision. The materials used in investment casting include:
- Stainless steel
- Carbon steel
- Alloys of nickel, cobalt, aluminum, and copper
What Are The Applications Of Investment Casting?
Many materials can be used for precision investment casting in different industries.
The method has been used for ages to cast jewelry and smaller components such as sculptures.
Currently, the process is part of industrial supply chains that comprise medical equipment, automotive parts, aerospace components, and rail and mining tools.
In other words, every manufacturing process that requires precise metal parts can use investment casting.
As much as investment casting is applicable in many industries, the two most common sectors include aerospace and firearms.
In the aerospace industry, precision casting is used to make engine parts. Since naturally occurring metals are considered too soft to be used in the aerospace industry, alloys are preferred.
In the firearms industry, investment casting is used to make smaller parts that form firearms. The parts may include the trigger or hammer. These components are required without defects to make weapons more functional.
Other industries that use investment casting include food services and any other that needs more diminutive, more intricate, and precise parts.
What Are The Advantages And Disadvantages Of Investment Casting?
Investment casting is preferred because of its benefits.
However, this does not mean it is short of drawbacks. Here are some notable pros and cons of investment casting:
Advantages of Investment Casting
- It can be used to cast components with incredibly intricate features and shapes.
- It is much easier to achieve tighter tolerance with excellent dimensional accuracy.
- Investment casting offers an excellent surface finish.
- The process does not require additional machining.
- The used wax can be reused again, making it more cost-effective.
- The process tends to be more time-efficient.
- Many components can be manufactured using a single mold.
- Products that require high-melting points and difficult to machine can be cast using investment casting where other casting techniques have failed.
It is worth noting that these advantages may differ from one manufacture to the other depending on the volume of production, the metal used, and the required product.
Additionally, the benefits of investment casting come at a significant price. Overall, the cost may be high when the volume of parts to be produced is low.
Disadvantages of Investment casting
- Investment casting tends to be more complex, with many steps that make it relatively expensive. However, some of these steps can be eliminated through automation.
- The dies involved in the process tend to be costly, making investment casting viable only for large-scale production.
- The process may require highly specialized equipment, expensive refractory material, and extensive labor costs.
- Parts that require a core are hard to produce.
As much as investment casting is considered more precise with an excellent surface finish, the process is more complex and attracts higher costs.
Additionally, other components may not be produced using investment casting, especially when the parts require a core.
Therefore, you must check all the product properties you want to manufacture to see if investment casting is the most suitable option.
Conclusion
Investment casting is a complex casting technique that requires extensive skills at every phase of production.
However, the method is more effective than any other casting technique if you want components with high integrity and quality.
You may want to control the process to ensure you get precisely what you desire.