3D printing, also known as additive manufacturing, can be used alongside traditional casting processes to provide product designers with greater design freedom and faster development turnaround times.
When people think of 3D printing, they usually think of direct metal printing techniques such as DMLS (Direct Metal Laser Sintering) and EBM (Electron Beam Melting), which use a focused heat source to melt metal powder or wire, forming components layer by layer. While on the surface this technique can be seen as an alternative to casting, in practice there is little overlap in application.
In this article, we will explore how 3D printing with sand, wax and polymers can complement existing casting processes and provide additional benefits for customers.
3D printing in sand casting
Sand casting, a process in which molten metal is poured into a mold made of sand that contains cavities of the desired shape. Sand cores are used if openings are required in the casting.
In traditional sand casting, both the mold and core are produced using patterns and must be made from resin beforehand. Sand 3D printing allows us to bypass this step and produce molds and cores without the need for a pattern. The printer produces molds and cores directly by gluing sand layer by layer from the CAD model. This greatly reduces the time and cost required for new product development.
3D printing with sand also enables greater design freedom, which means we can produce highly complex mold and core shapes and, in some cases, features not possible with traditional methods.
The use of 3D printing in sand casting benefits the development of new products, especially where speed to market is a factor, as it reduces the time and cost associated with producing prototype parts and conducting multiple design iterations. It is also particularly suitable for casting small volume, highly complex parts with complex features and internal voids. Therefore, it is very suitable for applications in certain industry sectors, such as high-performance vehicles.
3D printing in investment casting
Also known as lost wax casting, this process is used by our sister company Investacast to produce components for a wide variety of industries in many different alloys.
The investment casting process begins with the production of a tool from which a sacrificial wax replica of the part to be manufactured is produced. The wax is then coated in a ceramic slurry, which cures to form a crust around the wax. The wax is then burned off, leaving a hollow shell into which the molten metal is poured.
By 3D printing a wax replica of a part, usually using wax, but sometimes a polymer material, eliminating the need to produce a hard mold at the beginning of the casting process. The benefits are very similar to those of sand casting mentioned earlier: reduce the time and cost of the new product development process; and enable greater design freedom.
Generally, the end-to-end process of investment casting is longer than sand casting, which makes the use of 3D printing more beneficial for investment casting projects that are time-critical or whose designs are not fixed. It is particularly suitable for small, highly complex assemblies with complex features.
3D printed prototype
Another area where 3D printing is particularly useful is the production of prototype component models to aid technical discussions in product development.
The ability to view and manipulate designs in three dimensions aids product improvement and decision making, enabling designers and engineers to evaluate features such as radius and draft angle.
While casting or machining prototypes can be slow and costly, direct 3D printing in polymers enables faster design validation and enables rapid design iterations. Customers can see prototypes at an early stage, speeding up the process and giving them more freedom to innovate. Only after the design is complete do we work on machining and pouring the metal.
3D printing complements traditional casting
Metal casting is one of the oldest manufacturing methods, dating back more than 5,000 years. Today, innovations in 3D printing complement these traditional processes, offering customers greater flexibility.
By 3D printing molds and cores in sand, we achieve greater design freedom, reduce the time and cost of new product development, and enable complex features that would otherwise be impossible.