Casting is one of the oldest manufacturing techniques dating back to 1838. While the basic casting process hasn’t changed much, today’s machines are more advanced and with improvements in technology, there are a several different ways to reach your end product—or part so to speak. Two common and very similar processes are die casting and Investment Casting. Keep reading and we’ll discuss the difference between each process and help you to understand the advantages and disadvantages of each so that you can choose the right process for your next project.
The Die Casting Process
Simply put, when die casting a part, molten metal is injected into a hardened steel die cavity. When the metal solidifies it is ejected from the tool and the process is repeated. The process varies slightly depending on the material you choose—see hot chamber and cold chamber die casting. The hardened steel mold is capable of creating anywhere from 150,000 shots to over a million shots before it would need to be repaired or replaced.
Creating a part using the investment casting or “lost wax” process is typically a more time-consuming process where a wax prototype of your part is made and then repeatedly dipped into liquid ceramic. The ceramic hardens and then the wax is melted out leaving you with a ceramic mold. Molten metal is then poured into the ceramic cavity where the wax once was. Once the metal solidifies, the ceramic mold is broken and removed leaving the metal casting. The mold used to create the wax pattern can be used many times however the ceramic mold is broken and discarded with each part. However, Signicast has automated every aspect of the investment casting process making one week lead times possible where the industry average is 8-16 weeks.
No two casting projects are the same and with different projects, there are different solutions. Here are a few things to consider before you start your next project to help you choose which process is right for your component.
Most die cast parts are made from non-ferrous metals like zinc, aluminum, and magnesium. Investment casting is capable of casting cast those metals along with ferrous metals, including stainless steel. If you are looking to use a non-ferrous material, both processes offer comparable features. However, if you are looking to use stainless steels or copper alloys, investment casting is the better option.
When deciding which casting process to use, decide what your desired payback period is for the tool cost. How many parts created versus the cost of the tooling to “break even.” While investment casting tooling may be cheaper and suitable for lower volume projects, die casting is ideal for larger production runs and high-volume projects.
With any casting process, tolerance capabilities are largely influenced by the shape of the part and the type of material used. The table below compares general linear tolerances for conventional die casting and investment casting. The multi-slide die casting process is capable of holding even tighter tolerances.