Developing investment castings involves creating an original wax model, coating the image with plaster and building of successive layers until a strong shell envelopes the model. After melting out the wax, molten gold or bronze will be poured into the mold, creating a perfect duplicate of the original wax pattern.
Compared to machining apart, investment casting can economically offer undercuts, high definition, complex detail and a smooth surface finish.
Most often, investment casting is the only way a part can be economically manufactured
Investment Casting Benefits
Investment Casting vs. Sand Casting
Sand castings are made by creating a negative in a bed of sand to create the cavity for casting. A sand shell creates a rough exterior to castings. Typical surface finish of sand castings are 250 Ra as cast, and need extensive work afterwards to create a surface finish that is acceptable in most applications. Sand castings can also not hold as tight of tolerances as Investment Castings, and will likely need more machining than an Investment Casting.Investment casting uses a ceramic mold that can produce a much smoother finish, typically averaging 125 Ra surface finish as cast. Investment castings also greatly reduce the amount of machining that will be required after casting by holding a .005”/inch tolerance for the majority of applications.
Investment Casting vs. Metal Fabrication
Metal fabrications are metal structures produced by cutting, bending, and welding multiple pieces of material together. The result is multiple steps in the process, and causing higher scrap. The increase in wasted materials, along with increased labor time, causes metal fabrications to be expensive and time consuming. Without careful craftsmanship, or extensive work after completion, metal fabrications can look sloppy to end users.
Investment casting can cut down labor time and offer one continuous part that has a consistent and clean look to the end user. The reduction of labor time reduces lead times and cost of castable applications. The consistency in castings can also lead to lower scrap, lowering final costs even further.
Investment Casting vs. Machining
When machining parts out of metal stock all but the most simple of designs leads to a large amount of material wasted. Excess material leads to higher costs. Machining can also be a very lengthy process leading to longer lead times and more expensive parts.
Investment castings reduce waste, labor time, and machine time that causes machining to be costly. Milwaukee Precision Casting, in tandem with Milwaukee Precision Machining, can offer the best of both processes. The use of both processes allows Milwaukee Precision Casting to give the best possible price for casting, but allowing the end user to be able to install threads, hold tight tolerances, and improve surface finish where necessary.
Investment Casting vs. Die Casting
Die casting is the process in which molten metal is forced into a mold cavity. Using molten metal requires tooling that is made of hardened tool steel, which causes start-up costs to new programs to be extremely expensive. Tools also wear quickly, requiring expensive refurbishments and replacements throughout the life of the tool. Ferrous metals, like carbon steel and stainless steel, cannot be cast using this method, further limiting its usefulness.Investment casting injects wax into an aluminum cavity. Aluminum has a lower cost, is easier to cut, and less expensive to maintain. Using wax also is easier on tooling, allowing it to maintain consistent parts for many more uses. Investment casting allows for ferrous and non-ferrous metals (aluminum, brass, bronze, etc) to be cast.
Investment Casting vs. Forging