Casting is a method pouring melton metal into mold for desired dimensions. Investment casting and die casting are the two major types of casting. According to the advantages and disadvantages of each process, they are used to make different kinds of products. So how investment casting compares to die casting?
Investment casting is also called precision casting, or lost wax casting. The process starts from creating a wax pattern like the shape of desired component. Attaching the wax model to the sprue repeatedly to form tree assembling. Dipping the assembly into liquid ceramic to form a protective layer and removing the wax by heating in the oven. Then caster will fill the shell with liquid metal and cool in the room temperature. Finally cutting the shell to get solid shape components.
There are lots of investment casting advantages. For example, It is good for complex design products. Investment casting is used if you need zero draft angles on the part, something die casting cannot offer. Investment is more suited to lower volume quantities since the tooling is less but the part prices is higher than die casting.
Die casting works by forcing molten metal into a die cavity with high pressure. The caster machines a die cavity tree with hardened tool steel in the shape of the desired parts. A release agent is applied to the die, and then a sleeve is filled with molten metal that is then pushed into the die cavities with a piston. The piston keeps applying pressure to the metal as it fills the die. When the metal cools enough, the caster removes the casting tree from the die and trims the individual parts off the casting tree. Then each part is machined as necessary to finish it off.
There are a number of advantages to die casting. For one, die casting is well-suited to large production runs and high volumes because you get consistent repeatability. For another, you have fewer size restrictions with die casting, since you don’t need to worry about keeping molds for larger parts gated to a sprue for repeated dipping, as you do with the wax forms with investment casting. Also, having something investment casted tends to cost more due to the higher amount of manual labor and precision involved.
Differences between Investment Casting and Die Casting
1) Design Complexity: Investment casting offers greater design flexibility as we can cast complex shapes into the component. After investment casting, we can achieve precise dimensions, complex geometries and thin-walled parts. However, die casting also offers precise dimensional results but cannot produce as complex as investment casting.
2) Material Selection: Investment Casting process allows for both ferrous and non ferrous alloys, which offers a wide range of material selection. By comparison, Die casting is mostly adapted for material like aluminum, zinc and magnesium alloys.
3) Part Size: In our foundry, we can make investment castings up to weight 120lb. Investment casting is limited to the size of part as the wax model must be safely sticked to the sprue and repeated dipped in the ceramic slurry. Die Casting has less size limitation than investment casting and can creat larger components, but it will cost more in both tooling cost and unit cost for larger products.
4) Cost: Investment casting is a highly manual working process to produce superior dimensions and good surface finish. So it seems like a high cost casting method. Investment casting is also the most possible technique to reduce or aviod seconary machining, which reduce both time and money. Die casting cost more due to its high tooling cost and sometimes post machining operations for finished components. So die casting is more cost effective for large order quantity.
5) Surface Finish: During all casting techniques, surface finish of investment casting is always the best, and can reach precise tolerance IT5-6 with A 125 micro finish. While die casting produces good surface finish, more machining is usually needed to get the product to its final state. But we can both improve the surface finish of investment casting and die casting by secondary machining and other surface treatment ways.
No matter which process is choosed for your project, it all depends on your specific needs of products, as each process has its own benefits. Investment casting is considered when you have a small product with complex shape. And the material is steel or iron. If you are looking for a casting method with high volume, and the material is alunumin or zinc, then die casting is your right option.
Related article Investment Casting vs Sand Casting…