Month: May 2023
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Machining of metals
The final stage in the fabrication of aircraft metal structures involves the machining operations of milling, routing, trimming and drilling. Metal components are rarely in their final shape at the end of processing, and it is necessary to remove excess material using a variety of machining processes. Increasingly, these processes are being carried out automatically…
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Powder metallurgy for production of aerospace superalloys
Forging, extrusion, rolling and other working operations are used in the forming and shaping of aluminium, magnesium, titanium and steel structural components for aerospace applications. However, it is difficult to shape nickel-based superalloys for jet engine components using these same working operations. Superalloys are so-named because of their very high alloy content; typically 40–60% of…
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Hot and cold working of metal products
Hot working Plastic forming of wrought metals by process operations such as forging, extrusion and rolling is performed under hot working or cold working conditions. Hot working is the plastic deformation and shaping of a metal above its recrystallisation temperature. A large number of dislocations are generated by strain hardening during the plastic forming of…
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Metal-forming processes
Forging Forging is a forming process used to strengthen and shape thick sections of cast metal. The process involves plastically deforming the metal under high compressive forces inside a die cavity, as shown in Fig. 7.2. Deformation usually occurs by repeated strokes or blows applied using hammers, mechanical presses or hydraulic presses. The metal is plastically deformed…
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Introduction
Metals are not used in their as-cast condition for safety-critical aircraft structures or load-bearing jet engine components. The use of cast metal in the primary structures of commercial airliners is virtually nonexistent, and it is used sparingly in military aircraft. Cast metals are used in a small number of nonstructural components on aircraft and helicopters,…
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Casting processes
There are many commercial processes to produce castings for processing into aircraft components. Casting processes are usually classified into two broad groups distinguished by the mould type: reuseable casting moulds and single-use casting moulds. This section briefly describes the processes commonly used for casting metals for aircraft structures and engines. The processes are permanent mould…
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Casting of metal alloys
Shape and ingot castings Casting is the operation of pouring molten metal into a mould and allowing it to solidify. The pouring temperature is usually 50–180 °C above the melting point of the metal alloy. There are two broad classes of casting operations known as shape casting and ingot casting. Shape casting involves pouring the liquid…
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Production of metal alloys
Addition of alloying elements to metal Metals are not used in aerospace applications in their pure (unalloyed) condition. Pure metals are too soft to use in aircraft structures and engines, and must be alloyed with other elements to produce high-strength materials. For instance, the addition of a few percent of copper to aluminium increases the…
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Introduction
There are many stages in the manufacture of aircraft structures and engine components using metals, and it begins with the production and casting of the metal alloy. The mechanical properties, corrosion resistance and many other properties that influence the selection and performance of metals in aircraft are determined by their method of production and casting.…
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Certification of aerospace materials
Pyramid approach to aircraft certification The certification of structural and engine materials is one of the most important issues with the testing and evaluation of new aircraft. Certification is also performed when new materials are used in major structural refits of existing aircraft, usually for life extension. Certification is essential to ensure the materials are…