When selecting a production process for your part, factors such as cost, design requirements, and ability to manufacture influence which casting process is right for your product. This article discusses the investment casting process, also known as “lost wax” casting, and can help you decide when to use this process to manufacture your part.
Investment casting is a process that delivers castings of very high detail, tight tolerances and thin walls. Investment castings are often used to reduce or eliminate the need for machining or in the place of fabrications to reduce cost. Investment casting produces precise components while minimizing material waste. It can also ensure the production of very intricate parts.
In the investment-casting process, a wax pattern of the desired finished part is created and mounted onto a wax tree. The wax tree is then dipped into a ceramic slurry and sprinkled with stucco material in a controlled atmosphere and allowed to dry. This process is repeated until a thick shell is created over the wax pattern. The wax is melted out, leaving a cavity in the shape of the pattern. The cavity is then poured with molten metal and allowed to solidify. After solidification, the shell is broken away, gating material removed, and the finished part remains.
Advantages of utilizing investment castings
- Size range – while most investment castings are small, it’s able to produce castings that weigh more than 1,000 pounds.
- Versatile and intricate shapes – investment casting provides consistent and repetitive close tolerances along with intricate passages and contours.
- Accurate and smooth surfaces – the ceramic shell used is built around smooth patterns produced by injecting wax into a polished aluminum die. Investment castings contain no parting line because only one mold is used rather than two half molds (such as in the case of sand casting).
- Dimensional accuracy – typically, “standard” investment tolerances are +/-0.010” for the first inch and +/- 0.004” for each succeeding inch.
- Quality and integrity – investment casting has a long history of serving demanding sectors such as gas turbine engine, petroleum, chemical, defense, and medical.
When to use investment castings
Tooling cost, size limitations, internal structure and shape, and processing time are important components to consider when deciding if investment casting is the right process for your project. Generally, investment casting is the appropriate application for:
- Parts requiring fine detail and surface finish
- When needing difficult internal structures
- Parts with thin walls
- Parts with tight tolerances
Typical investment casting products
Because investment casting has a long history of serving demanding industries, products produced through this process are varied.
- Aerospace turbine blades
- Nuclear pump and valve components
- Flow meter bodies
- Flow nozzles
- Food processing components
- Military components
Learn more about investment casting capabilities, materials, and standards. Want a solutions expert with industry expertise to advise on the optimal process to produce your part or just have a question? Contact us today to talk with a metals solutions expert. Follow MetSource on LinkedIn to stay up to date on metal casting and industry information.
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