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What to consider when choosing the right casting process.

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 as technology improves, there are a few different ways to reach your final product or part speak. Two common and very similar processes are die casting and investment casting. Read on as we discuss the differences between each process and help you understand the pros and cons of each so you can choose the right process for your next project.

Die casting process

Simply put, when a part is die cast, molten metal is injected into a hardened steel mold cavity. When the metal solidifies, it pops out of the tool and the process repeats. The process will vary slightly depending on the material you choose - see Hot and Cold Chamber Die Casting. Hardened steel molds are capable of making 150,000 to over 1 million shots before needing repair or replacement.

Investment casting process

Manufacturing parts using investment casting or the "lost wax" process is often a more time-consuming process in which a wax prototype of the part is made and then repeatedly dipped into liquid ceramic. The ceramic hardens, then the wax melts, leaving behind a ceramic mold. The molten metal is then poured into the ceramic cavity where the wax used to be. Once the metal solidifies, the ceramic mold is broken and removed, leaving behind the metal casting. The molds used to create wax patterns can be used multiple times, but ceramic molds are discarded as each part is damaged. However, Signicast has automated every aspect of the investment casting process, enabling one-week lead times, compared to the industry average of 8-16 weeks.

Which process is right for my project?

No two casting projects are the same, and different projects have different solutions. Before you start your next project, here are a few things to consider to help you choose the right process for your components.

material selection

Most die castings are made of non-ferrous metals such as zinc, aluminum and magnesium. Investment casting materials can be these metals as well as ferrous metals, including stainless steel. If you are looking to work with non-ferrous materials, both processes can provide similar functionality. However, if you want to use stainless steel or copper alloys, investment casting is a better choice.

Annual output

When deciding which casting process to use, determine the payback period required for tooling costs. How many parts are created versus the "break-even" tool cost. While investment casting tools may be cheaper and suitable for small batch projects, die casting is ideal for high volume production and high volume projects.

tolerant

As with any casting process, the tolerance capability is greatly affected by the part shape and the type of material used. The table below compares the general linearity tolerances for traditional die casting and investment casting. The multi-slide die casting process is able to maintain tighter tolerances.

cycle

While both investment casting and die casting produce complex parts, cycle times vary widely. Traditional investment casting is a just-in-time process that requires a lot of labor and hours of work, while traditional die casting can produce 3-4 times per minute, and multi-slide die casting can produce more than 45 times per minute. Die castings are often created without human hands - fully automated!

cost

Cycle time determines 60% of the final part cost, so it's no surprise that investment casting costs per part are typically higher than die casting. Its highly manual process produces parts very similar to die casting, but with much longer cycle times.

Die casting is more cost-effective than investment casting when casting large quantities. If you are only casting a few parts or need larger sizes or stainless steel, investment casting may be a lower cost option.