Lost wax casting, also known today as investment casting, is a method of metal casting in which molten metal is cast into a design that has been created from a wax mold. Although it has been around since the third millennium BC, this method is still used today for the flexibility it allows to develop intricate, complex designs without having to account for post-process finishing or shrinkage of the component.
In fact, the global investment casting market size, valued at $16.63 billion in 2019, is expected to increase over the next half decade, driven primarily by the rising usage of investment casting in the aerospace and automotive industries for the development of advanced components, including engine parts, compressors and gearbox components.
Are you asking yourself, “What is the lost wax casting process?” We have the answers. In this blog post, we illustrate the investment casting process, as well as the advantages and industries that benefit most from this process.
What Is the Process of Lost Wax Casting?
With lost wax casting, it’s all in the details. This process is used to create parts that require tight tolerances, thinner walls and superior dimensional accuracy from a computer-aided design (CAD) using wax to create the shape and structure of the piece to be produced. One of the many benefits is the minimal finishing process, which reduces time, and therefore cost, from the overall process.
Investment casting requires multiple steps, beginning with the design, also considered the master pattern, for replicability:
- Creation of the die: In the first step, the die is created based on the 3D CAD rendering of the part.
- Producing the wax pattern: Wax is poured into the die to form the pattern. This is repeated for the number of parts to be cast.
- Wax pattern tree: The sprue, or the vertical passage through which liquid material runs, connects the wax patterns to form the tree.
- Shell building: The pattern is dipped in a liquid ceramic binder to form a hard exterior shell, leaving one end of the tree exposed for wax removal.
- Dewaxing: To remove the wax, the shell is placed into an oven, melting the wax so that it can run out of the shell.
- Burnout: To remove residual wax and moisture, the shell is again placed into an oven at an extremely high temperature, removing the extraneous materials and solidifying the ceramic mold.
- Casting: Molten metal is poured into the open side of the mold. From there, either gravity or a forced method distributes the metal, depending on the size of the mold and type of molten metal.
- Removing the mold: The ceramic mold is removed either by hammering the ceramic, blasting it with high pressure water or applying a chemical that includes liquid nitrogen.
- Cutting: Once the ceramic mold has been removed, the finished part is separated with a grinder. The waste material is collected for reuse.
- Finishing: To remove scales and residual material, the finished part is shot or sand blasted.
- Surface treatment: For components that need protection from rust, corrosion or weather damage, the component is dipped into an anti-rust solution or oil. Other surface treatments include painting or galvanizing.
Although the described process is not the only process, it is one of the more common approaches to investment casting.
The Advantages of Lost Wax Casting
Investment casting has very few restrictions on the types, dimensions and shapes available to the process, allowing engineers the flexibility to develop intricate and complex designs. While the advantages are many, here are several benefits to manufacturers.
Variety of Metals
With few limitations to the types of metals available to the process, engineers can select from an array of choices most useful to their industry.
Production Costs and Turnaround Time
Requiring less manpower, fewer resources and low post-processing, costs remain low and turnaround times fast.
Size Range and Intricacies of Design
The size range starts with something as small as a dental implant, and can be scaled to include something as intricate and finely detailed as engine parts weighing thousands of pounds.
With many more advantages, this process is beneficial for manufacturers in any industry.
The Industries Using Lost Wax Casting
With a wide variety of parts, products and components developed with a precise and accurate process, investment casting is beneficial to manufacturers in many industries, but particularly the following:
Essential to the construction of airplanes and spacecrafts, investment casting products can be found in every portion of flight vehicles, from bearings to complex parts of engines.
This industry relies heavily on investment casting for the production of engine components, suspension systems, fuel systems and more. This process is especially useful for this industry due to its excellent metal-to-metal lubrication and long wear.
The exactness of investment casting is perfect for the regulatory specifications required for products in this industry, including implants, forceps and surgical instruments.
Invest in Investment Casting Experts
With “what is the lost wax casting process?” answered, finding an OEM supplier to outsource your lost wax casting production is next. With nearly three decades in business and thousands of types of products in a variety of industries produced every year, VPIC Group will execute your investment casting project with the utmost care and precision, backed by constant communication.
Ready to take the first step towards your next investment casting project? Contact us today.