Die casting vs. investment casting

What is the difference between die casting and investment casting?

Casting is one of the oldest manufacturing techniques, dating back to 1838. While the basic casting process has not changed significantly, today's machines are more advanced and technological improvements have created several ways to produce your end product, or component. Two common and very similar processes are die casting and investment casting. Read on to learn about the differences between each process and understand their advantages and disadvantages, 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 die casting and cold chamber die casting. The hardened steel die can produce anywhere from 150,000 shots to over a million shots before requiring repair or replacement.

The investment casting process

Creating a part using the investment casting or "lost wax" process is typically more time-consuming. A wax prototype of your part is made and then repeatedly dipped into liquid ceramic. The ceramic hardens, and the wax is then melted out, leaving a ceramic mould. Molten metal is then poured into the ceramic cavity previously occupied by the wax. Once the metal solidifies, the ceramic mould is broken and removed, leaving the metal casting. The mould used to create the wax pattern can be used many times; however, the ceramic mould is broken and discarded with each part. Signicast has automated every aspect of the investment casting process, making one-week lead times possible, where the industry average is 8-16 weeks. 

Which process is right for my project?

No two casting projects are the same, and different projects require different solutions. Here are a few factors to consider before starting your next project to help you choose the right process for your component.

Material selection

Most die cast parts are made from non-ferrous metals such as zinc, aluminium and magnesium. Investment casting can cast these metals as well as 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.

Annual volume

When deciding which casting process to use, determine your desired payback period for tooling costs. Consider how many parts must be produced against the cost of the tooling to break even. While investment casting tooling may be less expensive and suitable for lower-volume projects, die casting is ideal for larger production runs and high-volume projects.

Tolerance

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 can achieve even tighter tolerances.

Cycle time

While investment casting and die casting both produce complex parts, their cycle times differ greatly. Traditional investment casting is a time-consuming process requiring considerable labour and many working hours, while die casting can produce 3-4 shots per minute for conventional die casting and upwards of 45 shots per minute with multi-slide die casting. A die cast part can often be produced without human intervention—through complete automation. 

Cost

Cycle time determines up to 60% of your final part cost, so it is no surprise that, per part, investment casting generally costs more than die casting. Its highly manual processes yield parts very similar to die cast parts, but the cycle time is much longer. 

For high-volume casting, die casting is more cost-effective than investment casting. If you are casting only a few parts or require larger sizes or stainless steel, investment casting may be the lower-cost option.

While both investment casting and die casting produce parts with comparable features, when extremely high-volume manufacturing is required, the associated costs and longer cycle times can make investment casting a less suitable option depending on your needs and deadlines. It is advisable to consult an experienced casting engineer to determine which casting process is best suited to your next project—contact our team today!