Casting of Gas Turbine Blades — Preferred Process For producing aerodynamically accurate, high-temperature-capable gas turbine blades, which casting process is most preferred?

Introduction / Context:
Gas turbine blades require precise airfoil profiles, smooth surfaces, and often advanced metallurgy (directionally solidified or single-crystal structures). The casting process must satisfy tight dimensional tolerances and metallurgical control.

Given Data / Assumptions:

• Material: superalloys (nickel/cobalt-based) for hot sections.
• Geometry: thin sections, cooling passages, high surface finish.
• Production requirement: excellent dimensional accuracy and surface quality.

Concept / Approach:
Investment casting (lost-wax process) uses ceramic shells built on wax patterns. It enables complex geometries, fine details, and smooth surfaces, and is compatible with directional solidification or single-crystal techniques essential for creep and fatigue resistance at elevated temperatures, making it the benchmark process for turbine blades.

Step-by-Step Solution:
Identify critical needs: precision airfoil geometry and advanced solidification control.Match process capabilities: investment casting allows intricate internal passages and superior finish.Exclude general processes with poorer accuracy (sand) or limited alloy/process compatibility (die casting for high-temp superalloys).Select investment moulding.

Verification / Alternative check:
Aerospace foundries universally employ investment casting for turbine hot-section components.

Why Other Options Are Wrong:
Die casting: suited to low-melting alloys (e.g., Zn, Al), not superalloys.Shell moulding/sand casting: improved over plain sand, but still inferior to investment casting for airfoils.

Common Pitfalls:
Confusing shell moulding (a sand process) with ceramic-shell investment casting.

Final Answer:
investment moulding