Which casting process yields a finer finish and closer tolerances, but at higher cost and longer lead times?

Which casting process yields a finer finish and closer tolerances, but at higher cost and longer lead times?

• A. Sand casting yields a finer finish and closer tolerances, but at higher cost.
• B. Sand casting yields rougher finishes and looser tolerances.
• C. Investment casting yields a finer finish and closer tolerances, but at higher cost and longer lead times.
• D. Sand casting yields finer finish but longer lead times.

Answer: (C)

The key idea is the trade-off between surface finish and dimensional accuracy versus cost and lead time among casting methods. Investment casting uses a precise ceramic shell built around a wax pattern, then the wax is burned out and metal is poured into a very smooth, accurate mold. This results in a finer surface finish and tighter tolerances on the finished part. Because the process involves multiple detailed steps (pattern making, shell building, burnout, and careful finishing), it costs more and takes longer to produce, hence higher lead times. In contrast, sand casting uses a loose sand mold that’s quicker and cheaper to make, but it yields a rougher surface and looser tolerances, with shorter lead times.

The key idea is the trade-off between surface finish and dimensional accuracy versus cost and lead time among casting methods. Investment casting uses a precise ceramic shell built around a wax pattern, then the wax is burned out and metal is poured into a very smooth, accurate mold. This results in a finer surface finish and tighter tolerances on the finished part. Because the process involves multiple detailed steps (pattern making, shell building, burnout, and careful finishing), it costs more and takes longer to produce, hence higher lead times. In contrast, sand casting uses a loose sand mold that’s quicker and cheaper to make, but it yields a rougher surface and looser tolerances, with shorter lead times.