Advantages and Disadvantages of Investment Casting

Before we dive deeper and get to know the advantages and disadvantages of the investment casting, let’s revive a bit of our understanding of the process of investment casting.

Investment casting is a widely and commonly used practice to produce and remake identical metal parts with complete precision by using a wax pattern and then pouring hot metal in liquid form into the wax pattern.

Here’s a brief description of the investment casting process followed by a brief mention of the advantages and disadvantages of this process.

Investment Casting Method

The process of investment casting uses expendable wax patterns. For the process of investment casting, first and foremost, wax patterns are prepared.

These wax patterns are mostly prepared by injection molding technology. In the cavity, that’s similar to the desired cast part.

Then wax patterns are attached to a gating system (a set of channels) through which molten metal will flow and fill the mold cavity.

Shell building is the next stage where the wax assembly is immersed into a refractory ceramic slurry of hardening mixtures. Then it is allowed to get dried. This process is repeated multiple times until there’s a formation of a solid ceramic shell approximately of thickness 6mm – 9mm.

The next step of the process is to dewax. The assembly is heated in an autoclave to melt out the wax from it. The residual wax remains are burned out in a furnace.

The mold is now free of wax and ready to be filled by molten metal but before that, it is preheated to a temperature range of 1830 degrees F. Molted metal can be poured in this preheated mold.

Molten metal is poured in the mold through the gating system to which the shells were attached earlier in the process of investment casting.

The pouring of molten metal through the gating system is called casting stage.

After pouring, the metal is allowed to solidify and get cooled to come to the desired temperature. After this, the shell is broken and the casting is cut away from the gates and sprue.

The last step of investment casting is the finishing stage and that’s carried out either by sandblasting or machining.

Advantages of Investment Casting

• Investment casting offers an excellent surface finish. In this method, mostly ceramic molds are used that can produce a smooth finish.
• Tight dimensional tolerances. Given the standard tolerance is +/- .005 per inch, this also shortens the amount of machining required.
• Faster production of metal casts is possible through this procedure and it reduces the amount of machining required after casting.
• It can cast thin walls.
• It can also produce complex and intricate shapes that are otherwise hard to make by other methods and procedures.
• A large variety of metals can be cast by following the process of investment casting.
• In the process, minimal wastage of the material happens.
• An added advantage is that no draft is required in the mold’s design.
• Less expensive equipment is needed to conduct the process of investment casting and they are not dangerous to use.
• Casts of any size – large or small can be prepared by investment casting. Intricate and miniature parts can be cast easily and also the large parts with the same ease.
• A wide range of materials can be used for this process. You can use bronze, stainless steel, aluminum, etc.

Disadvantages of Investment Casting

While investment casting has quite a few advantages like any other process it also has few disadvantages. It will be helpful to know about them too.

• For each casting, an individual pattern is required. And this makes it a costly process.
• There is a limit to the casting dimensions also the tooling and the labor costs are relatively higher.
• When it comes to casting objects with a core, investment casting can prove to be a difficult process.
• If compared with other casting processes the production cycle for the investment casting is longer.

Conclusion

If you compare, then the disadvantages are only a few whereas the advantages of the investment casting process are many.

Investment casting is a process that can help remake metal parts, either miniature or large, with great surface finishing and total remake of the intricate details.

With these many advantages, investment casting makes a reliable process to make high-quality metal parts that are the exact remake of the original metal part design.