Jawaharlal Nehru Technological University Hyderabad B.Tech II AIRCRAFT PRODUCTION TECHNOLOGY Previous Question Paper (March - 2022 - R13)

Aircraft castings are primarily used for complex, non-structural or semi-structural components where high strength-to-weight ratios are achieved through specialized alloys. Key parts include engine components, landing gear fittings, and control system housings.

Examples include:

1. Engine Components: Compressor casings and turbine housings are cast from heat-resistant superalloys to withstand extreme temperatures and pressures.
2. Landing Gear Fittings: Complex brackets and hinges are often cast from high-strength steel or titanium alloys to provide the required geometry for load distribution.
3. Control System Housings: Bell cranks, pulleys, and actuator housings are cast from aluminum or magnesium alloys to reduce weight while maintaining dimensional accuracy.

Justification: Casting allows for the production of intricate internal geometries and complex shapes that would be difficult or impossible to machine from solid billets, while minimizing material waste and assembly time.

The characteristics of an oxy-fuel welding flame are determined by the ratio of oxygen to acetylene, resulting in three distinct zones: the inner cone, the intermediate zone (acetylene feather), and the outer envelope.

The three primary flame types are:

1. Neutral Flame: Produced with a 1:1 ratio, it has a clear inner cone and is used for most standard welding operations.
2. Oxidizing Flame: Contains excess oxygen, resulting in a shorter, pointed inner cone; it is used for welding brass or bronze.
3. Carburizing (Reducing) Flame: Contains excess acetylene, showing a white feather; it is used for high-carbon steels and hard-facing.

Regarding torch position and angle:

1. Torch Angle: Typically maintained between 30 and 60 degrees relative to the workpiece. A shallower angle provides less penetration and is used for thin sheets, while a steeper angle increases heat concentration for thicker sections.
2. Torch Position: In forward welding (forehand), the torch moves toward the filler rod, providing better visibility and control. In backward welding (backhand), the torch moves away from the filler rod, which is preferred for thicker materials to improve penetration and heat management.