Superforming

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Superforming is a hot metal forming process that uses similar principles to thermoforming plastics, where a sheet of material is heated and forced onto a male or female form using gas pressure. The process is useful for producing complex surfaces. [1] The technique was pioneered for use in alloy fighter jets, with a sheet of aluminum heated like "taffy" and then "blown" into a mold by a press system, allowing complex curves. [2] It heats the sheets to 500 degrees Celsius, and after molding, vacuums out the air. [3]

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Use in transportation

The Jaguar I-Pace was the world's first structure to be made with superforming. [4] In 2015, McLaren announced that the 570S Coupe used superformed aluminum body panels. [2] The first Morgan Aero GTs released in 2018 used the process. [5] According to Bentley, the third-generation 2018 Bentley Continental GT is the first production car ever to have an entire body side made from the Super Formed process. [6] [7] The panels are "superformed" with heated aluminum sheets molded by gas instead of a stamp. [8] In particular, the fenders, hood, and doors and superformed. [9]

Variations in process

The superforming process varies mostly in the way that the metal is introduced to the form; the main 4 variations are:

Cavity forming
The metal in its plastic state is introduced to a negative form by gas pressure. It is good for large and complex parts such as automotive body panels and is excellent for shaping 5083 aluminium alloy.
Backpressure forming
The metal in its plastic state is introduced to a negative mould by gas pressure similarly to cavity forming; however, the pressure differential between the front and back of the metal is kept small and within tight tolerances. This maintains the integrity of the sheet and means that "difficult" alloys can be formed. It was developed to produce structural aircraft components in 7475 alloys.
Bubble forming
The metal in its plastic state is first expanded into a bubble with gas pressure; a positive form is then moved into the bubble cavity and the metal introduced to the form with reverse gas pressure. Suitable for deep complex components, especially where wall thickness needs to remain relatively constant. This process can be used to manufacture geometries that are impossible to achieve using any other forming process.
Diaphragm forming
A non-superplastic metal is introduced to a negative form by a superplastic metal which is itself being moved by gas pressure. It is used to shape complex sheet geometries in non-superplastics alloys such as 2014, 2024, 2219 and 6061. making the process ideal for producing structural components.

Superforming process is used to create complex sheet geometries from a single piece of material and this process has been rapidly growing in many applications, including aerospace, automotive, buildings, trains, electronics, furniture and sculpture. [10]

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Casting (metalworking) Pouring liquid metal into a mold

In metalworking and jewelry making, casting is a process in which a liquid metal is delivered into a mold that contains a negative impression of the intended shape. The metal is poured into the mold through a hollow channel called a sprue. The metal and mold are then cooled, and the metal part is extracted. Casting is most often used for making complex shapes that would be difficult or uneconomical to make by other methods.

Forging Metalworking process

Forging is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer or a die. Forging is often classified according to the temperature at which it is performed: cold forging, warm forging, or hot forging. For the latter two, the metal is heated, usually in a forge. Forged parts can range in weight from less than a kilogram to hundreds of metric tons. Forging has been done by smiths for millennia; the traditional products were kitchenware, hardware, hand tools, edged weapons, cymbals, and jewellery. Since the Industrial Revolution, forged parts are widely used in mechanisms and machines wherever a component requires high strength; such forgings usually require further processing to achieve a finished part. Today, forging is a major worldwide industry.

In materials science, superplasticity is a state in which solid crystalline material is deformed well beyond its usual breaking point, usually over about 600% during tensile deformation. Such a state is usually achieved at high homologous temperature. Examples of superplastic materials are some fine-grained metals and ceramics. Other non-crystalline materials (amorphous) such as silica glass and polymers also deform similarly, but are not called superplastic, because they are not crystalline; rather, their deformation is often described as Newtonian fluid. Superplastically deformed material gets thinner in a very uniform manner, rather than forming a "neck" that leads to fracture. Also, the formation of microvoids, which is another cause of early fracture, is inhibited.

Injection moulding Manufacturing process for producing parts by injecting molten material into a mould, or mold

Injection moulding is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals, glasses, elastomers, confections, and most commonly thermoplastic and thermosetting polymers. Material for the part is fed into a heated barrel, mixed, and injected into a mould cavity, where it cools and hardens to the configuration of the cavity. After a product is designed, usually by an industrial designer or an engineer, moulds are made by a mould-maker from metal, usually either steel or aluminium, and precision-machined to form the features of the desired part. Injection moulding is widely used for manufacturing a variety of parts, from the smallest components to entire body panels of cars. Advances in 3D printing technology, using photopolymers that do not melt during the injection moulding of some lower-temperature thermoplastics, can be used for some simple injection moulds.

Powder metallurgy

Powder metallurgy (PM) is a term covering a wide range of ways in which materials or components are made from metal powders. PM processes can avoid, or greatly reduce, the need to use metal removal processes, thereby drastically reducing yield losses in manufacture and often resulting in lower costs.

Bentley Continental GT Motor vehicle

The Bentley Continental GT is a grand tourer manufactured and marketed by British automaker Bentley Motors since 2003. It was the first car released by Bentley under Volkswagen AG management, after the company's acquisition in 1998, and the first Bentley to employ mass production manufacturing techniques.

Die casting Metal casting process that is characterized by forcing molten metal under high pressure into a mould cavity

Die casting is a metal casting process that is characterized by forcing molten metal under high pressure into a mould cavity. The mould cavity is created using two hardened tool steel dies which have been machined into shape and work similarly to an injection mould during the process. Most die castings are made from non-ferrous metals, specifically zinc, copper, aluminium, magnesium, lead, pewter, and tin-based alloys. Depending on the type of metal being cast, a hot- or cold-chamber machine is used.

Inconel Trademark of nickel-chromium superalloys

Inconel is a registered trademark of Special Metals Corporation for a family of austenitic nickel-chromium-based superalloys.

Hydroforming

Hydroforming is a cost-effective way of shaping ductile metals such as aluminium, brass, low alloy steel, and stainless steel into lightweight, structurally stiff and strong pieces. One of the largest applications of hydroforming is the automotive industry, which makes use of the complex shapes made possible by hydroforming to produce stronger, lighter, and more rigid unibody structures for vehicles. This technique is particularly popular with the high-end sports car industry and is also frequently employed in the shaping of aluminium tubes for bicycle frames.

Compression molding

Compression Moulding is a method of moulding in which the moulding material, generally preheated, is first placed in an open, heated mould cavity. The mould is closed with a top force or plug member, pressure is applied to force the material into contact with all mould areas, while heat and pressure are maintained until the moulding material has cured. The process employs thermosetting resins in a partially cured stage, either in the form of granules, putty-like masses, or preforms.

Rotational molding

Rotational molding involves a heated hollow mold which is filled with a charge or shot weight of material. It is then slowly rotated, causing the softened material to disperse and stick to the walls of the mold. In order to maintain even thickness throughout the part, the mold continues to rotate at all times during the heating phase and to avoid sagging or deformation also during the cooling phase. The process was applied to plastics in the 1950s but in the early years was little used because it was a slow process restricted to a small number of plastics. Over time, improvements in process control and developments with plastic powders have resulted in increased use.

Foundry

A foundry is a factory that produces metal castings. Metals are cast into shapes by melting them into a liquid, pouring the metal into a mold, and removing the mold material after the metal has solidified as it cools. The most common metals processed are aluminium and cast iron. However, other metals, such as bronze, brass, steel, magnesium, and zinc, are also used to produce castings in foundries. In this process, parts of desired shapes and sizes can be formed.

Aluminium alloy Alloy in which aluminium is the predominant metal

Aluminium alloys are alloys in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon, tin and zinc. There are two principal classifications, namely casting alloys and wrought alloys, both of which are further subdivided into the categories heat-treatable and non-heat-treatable. About 85% of aluminium is used for wrought products, for example rolled plate, foils and extrusions. Cast aluminium alloys yield cost-effective products due to the low melting point, although they generally have lower tensile strengths than wrought alloys. The most important cast aluminium alloy system is Al–Si, where the high levels of silicon (4.0–13%) contribute to give good casting characteristics. Aluminium alloys are widely used in engineering structures and components where light weight or corrosion resistance is required.

Fusible core injection molding, also known as lost core injection molding, is a specialized plastic injection molding process used to mold internal cavities or undercuts that are not possible to mold with demoldable cores. Strictly speaking the term "fusible core injection molding" refers to the use of a fusible alloy as the core material; when the core material is made from a soluble plastic the process is known as soluble core injection molding. This process is often used for automotive parts, such as intake manifolds and brake housings, however it is also used for aerospace parts, plumbing parts, bicycle wheels, and footwear.

Shell moulding, also known as shell-mould casting, is an expendable mold casting process that uses resin covered sand to form the mold. As compared to sand casting, this process has better dimensional accuracy, a higher productivity rate, and lower labor requirements. It is used for small to medium parts that require high precision. Shell molding was developed as a manufacturing process during the mid-20th century in Germany. It was invented by German engineer Johannes Croning. Shell mold casting is a metal casting process similar to sand casting, in that molten metal is poured into an expendable mold. However, in shell mold casting, the mold is a thin-walled shell created from applying a sand-resin mixture around a pattern. The pattern, a metal piece in the shape of the desired part, is reused to form multiple shell molds. A reusable pattern allows for higher production rates, while the disposable molds enable complex geometries to be cast. Shell mold casting requires the use of a metal pattern, oven, sand-resin mixture, dump box, and molten metal.

Hot metal gas forming (HMGF) is a method of die forming in which a metal tube is heated to a pliable state, near to but below its melting point, then pressurized internally by a gas in order to form the tube outward into the shape defined by an enclosing die cavity. The high temperatures allow the metal to elongate, or stretch, to much greater degrees without rupture than are possible in previously utilized cold and warm forming methods. In addition, the metal can be formed into finer details and requires less overall forming force than traditional methods.

Friction stir processing

Friction stir processing (FSP) is a method of changing the properties of a metal through intense, localized plastic deformation. This deformation is produced by forcibly inserting a non-consumable tool into the workpiece, and revolving the tool in a stirring motion as it is pushed laterally through the workpiece. The precursor of this technique, friction stir welding, is used to join multiple pieces of metal without creating the heat affected zone typical of fusion welding.

Metal spinning

Metal spinning, also known as spin forming or spinning or metal turning most commonly, is a metalworking process by which a disc or tube of metal is rotated at high speed and formed into an axially symmetric part. Spinning can be performed by hand or by a CNC lathe.

Alonizing is a diffusion metallizing process in that it is a thermochemical treatment that involves enriching the surface layer of an object with one or more metallic elements. Specifically, alonizing is the diffusion of aluminum into the surface of a base metal through high temperature vapors. The types of metals that can be alonized include all types of wrought and cast steels. This process results in an alloy with the surface properties of aluminum while retaining the base metal’s inherent strength and rigidity. Therefore, alonizing does not change the high-temperature mechanical properties of the base metal, which is the advantage of alonizing over simply creating an aluminum alloy.

Diffusion bonding

Diffusion bonding or diffusion welding is a solid-state welding technique used in metalworking, capable of joining similar and dissimilar metals. It operates on the principle of solid-state diffusion, wherein the atoms of two solid, metallic surfaces intersperse themselves over time. This is typically accomplished at an elevated temperature, approximately 50-75% of the absolute melting temperature of the materials. Diffusion bonding is usually implemented by applying high pressure, in conjunction with necessarily high temperature, to the materials to be welded; the technique is most commonly used to weld "sandwiches" of alternating layers of thin metal foil, and metal wires or filaments. Currently, the diffusion bonding method is widely used in the joining of high-strength and refractory metals within the aerospace and nuclear industries.

References

  1. Thompson, Ro. Manufacturing Processes For Design Professional. : Thames & Hudson 2007110.
  2. 1 2 https://www.forbes.com/sites/markewing/2015/03/31/mclaren-reveals-the-570s-coupe/#4fead3ee1422
  3. https://sg.asiatatler.com/life/third-generation-bentley-continental-gt
  4. https://www.autocar.co.uk/car-news/features/how-innovate-car-industry-according-jaguar-land-rover-engineering-chief
  5. https://www.wheels.ca/news/first-morgan-aero-gt-is-produced/
  6. https://www.autocar.co.uk/car-news/motor-shows-frankfurt-motor-show/new-bentley-continental-gt-revealed-full-specs-and-video
  7. https://www.bentleymedia.com/en/newsitem/784
  8. Ford, Tom (28 November 2017). "2018 Bentley Continental GT" . Retrieved 27 January 2018 via www.topgear.com.
  9. http://www.thedrive.com/new-cars/20876/2019-bentley-continental-gt-first-drive-review-the-new-bentley-is-almost-perfect-almost
  10. Rob Thompson. Manufacturing Processes For Design Professional. Thames & Hudson