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 part. Two common and closely related processes are die casting and investment casting. Read on to learn about the differences between these processes, as well as the advantages and disadvantages of each, so you can select the right process for your next project.

The die casting process

Simply put, die casting involves injecting molten metal into a hardened steel die cavity. Once the metal solidifies, it is ejected from the tool and the process is repeated. The process varies slightly depending on the material selected—see hot chamber die casting and cold chamber die casting. The hardened steel die can produce anywhere from 150,000 shots to more than a million shots before requiring repair or replacement.

The investment casting process

Producing a part using the investment casting or "lost wax" process is typically more time-consuming. A wax prototype of the part is produced and repeatedly dipped in liquid ceramic. The ceramic hardens, and the wax is then melted out, leaving a ceramic mould. Molten metal is 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 reused many times; however, the ceramic mould is broken and discarded for each part. Signicast has automated every aspect of the investment casting process, making one week lead times possible, compared with the industry average of 8-16 weeks. 

Which process is right for my project?

No two casting projects are the same, and different projects require different solutions. Consider the following factors before starting your next project to help determine which process is right 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 plan to use a non-ferrous material, both processes offer comparable features. However, if you require stainless steels or copper alloys, investment casting is the better option.

Annual volume

When deciding which casting process to use, consider the desired payback period for tooling costs. How many parts must be produced relative to the tooling cost 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

For any casting process, tolerance capability is largely influenced by the part shape and material type. 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 considerably. Traditional investment casting is a time-consuming process requiring substantial labour and working hours, whereas die casting can produce 3-4 shots per minute for conventional die casting and more than 45 shots per minute with Multi-Slide die casting. A die cast part can often be produced without human intervention—fully automated! 

Cost

Cycle time accounts for up to 60% of your final part cost, so it is unsurprising that investment casting generally costs more per part than die casting. Its highly manual processes produce 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 producing 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, the associated costs and longer cycle times can make investment casting a less suitable option when extremely high-volume manufacturing is required, depending on your needs and deadlines. Consult an experienced casting engineer to determine which casting process is best suited to your next project—contact our team today!