Assertion ( ) A : The investment casting is used for precision parts s...
Investment Casting for Precision Parts
Assertion (A): The investment casting is used for precision parts such as turbine plates, sewing machines, etc.
Reason (R): The investment castings have a good surface finish and are exact reproductions of the master pattern.
Explanation:
Investment casting is a manufacturing process used to produce highly accurate and complex metal parts. It is also known as lost-wax casting. In this process, a wax pattern is created, which is then coated with a ceramic material. The ceramic shell is then heated, and the wax is melted out, leaving a cavity in the shape of the wax pattern. Molten metal is poured into the cavity, and once the metal solidifies, the ceramic shell is broken away to reveal the finished metal part.
Investment casting is a suitable process for producing precision parts because of the following reasons:
- Complex shapes: Investment casting can produce parts with complex shapes that are difficult or impossible to produce with other methods.
- Tight tolerances: Investment casting can achieve tight tolerances, which is essential for precision parts.
- Excellent surface finish: Investment castings have a good surface finish, which requires minimal post-processing.
- Material flexibility: Investment casting can be used with a variety of metals, including aluminum, steel, and titanium.
Therefore, the assertion that investment casting is used for precision parts such as turbine plates and sewing machines is true.
The reason given for the assertion is also true. Investment castings have a good surface finish and are exact reproductions of the master pattern. The surface finish of investment castings is typically 125-250 microinches (3.2-6.4 micrometers), which is much smoother than other casting methods.
Therefore, both the assertion and reason are individually true, and the reason is the correct explanation of the assertion.
The correct answer is (a) Both A and R are individually true, and R is the correct explanation of A.
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