Brass Investment Casting
Brass investment casting is the manufacturing process that creates parts through the metallic replication of wax models. Investment casting using molten brass results in a final product that is very smooth and detailed without flash or parting lines. This technique creates parts that are precise and lightweight. A variety of metal alloys may be used, including aluminum, steel, and gold.
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Applications of Brass Investment Casting
Brass castings are used in many applications; metal parts are used industrially, commercially, and domestically everyday.
Investment casting is used in a variety of applications and industries, including:
- Dental and Medical Tools
- Food Processing
Process of Brass Investment Casting
Almost any castable metal may be investment cast. The investment casting process lends itself well to parts from a few grams to a few hundred pounds; most parts, however, are 15 pounds or less. The first step in investment casting is creating a master die out of wax. This wax pattern can be carved by hand or machine or produced through injection molding. The die is an exact replica of the part that is to be produced. It is attached to a wax rod called a sprue. Several hundred wax patterns may be attached to the same sprue, or it may be a single pattern. When the master dies are firmly attached, the assembly is inverted and dipped into a ceramic slurry called the investment. It may be dipped multiple times to achieve an even coating and the desired thickness.
An alternative method is to mount the assembly in a flask and to pour in the investment. The investment is then left to dry, which requires a number of hours unless the process is aided by a fan or vacuum. After it has dried completely, the assembly is inverted and baked in an oven or furnace in order to melt or vaporize the wax. The mold is heated more than necessary to guarantee that there is no moisture or residual wax inside that would interfere with the liquid brass that is then poured into the space left by the wax. To thoroughly fill the mold, the molten metal can be drawn in through vacuum, positive air pressure, or centrifugal casting methods. Sometimes the force of gravity is enough. The brass cools and, once it has hardened into a solid, the investment mold is removed to release the brass casting inside.
Factors to Consider When Using Brass Investment Casting
The main drawback to investment casting is that it is more expensive than other manufacturing methods. The equipment cost is typically lower than other methods and, after the parts are produced, they require little finishing or machining.