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59-647: The primary purposes of using a subframe are to distribute high chassis loads over a wide area of relatively thin sheet metal of a monocoque body shell and to isolate vibrations and harshness from the rest of the body. For example, in an automobile with its powertrain contained in a subframe, forces generated by the engine and transmission can be sufficiently damped to prevent disturbing the passengers. Modern vehicles use separate front and rear subframes to reduce overall weight and cost while maintaining structural integrity. Additionally, subframes benefit production by allowing subassemblies to be created and later introduced to

118-420: A YAG based laser with a wavelength of around 1 μm. Photochemical machining, also known as photo etching, is a tightly controlled corrosion process which is used to produce complex metal parts from sheet metal with very fine detail. The photo etching process involves photo sensitive polymer being applied to a raw metal sheet. Using CAD designed photo-tools as stencils, the metal is exposed to UV light to leave

177-497: A chassis. The same body design might then be adjusted to suit different brands of chassis. Examples include Salmons & Sons ' Tickford bodies with a patent device to raise or lower a convertible's roof, first used on their 19th-century carriages, or Wingham convertible bodies by Martin Walter . Separate coachbuilt bodies became obsolete when vehicle manufacturers found they could no longer meet their customers' demands by relying on

236-416: A class of structural steel . Sheet metal is available in flat pieces or coiled strips. The coils are formed by running a continuous sheet of metal through a roll slitter . In most of the world, sheet metal thickness is consistently specified in millimeters. In the U.S., the thickness of sheet metal is commonly specified by a traditional, non-linear measure known as its gauge . The larger the gauge number,

295-731: A coachbuilder may be called a "coachbuilt body" ( British English ) or "custom body" ( American English ). Prior to the popularization of unibody construction in the 1960s, there were many independent coachbuilders who built bodies on chassis provided by a manufacturer, often for luxury or sports cars. Many manufacturers such as Ferrari outsourced all bodywork to coachbuilders such as Pininfarina and Scaglietti . Coachbuilders also made custom bodies for individual customers. The coachbuilder craftsmen who might once have built bespoke or custom bodies continue to build bodies for short runs of specialized commercial vehicles such as luxury motor coaches or recreational vehicles or motor-home bodied upon

354-748: A coarser kind. From the beginning of the automobile industry manufacturers offered complete cars assembled in their own factories commonly using entire bodies made by specialist people using different skills. Soon after the start of the twentieth century mass production coachbuilders developed such as Mulliners or Pressed Steel in Great Britain, Fisher Body , Budd , Briggs in the U. S., or Ambi-Budd in Germany. Many other big businesses remain involved. Many coachbuilt chassis would come with all lights, standard instruments and their panel, engine cover, mudguards and running boards and spare wheel(s) There remained

413-459: A color-coated metal sheet. Sheet metal is used in automobile and truck (lorry) bodies , major appliances , airplane fuselages and wings , tinplate for tin cans , roofing for buildings (architecture), and many other applications. Sheet metal of iron and other materials with high magnetic permeability , also known as laminated steel cores , has applications in transformers and electric machines . Historically, an important use of sheet metal

472-431: A design pattern, which is developed and etched from the metal sheet. Perforating is a cutting process that punches multiple small holes close together in a flat workpiece. Perforated sheet metal is used to make a wide variety of surface cutting tools, such as the surform . This is a form of bending used to produce long, thin sheet metal parts. The machine that bends the metal is called a press brake . The lower part of

531-473: A laser for cutting compound shapes, but faster for repetitive shapes (for example, the grille of an air-conditioning unit). A CNC punch can achieve 600 strokes per minute. A typical component (such as the side of a computer case) can be cut to high precision from a blank sheet in under 15 seconds by either a press or a laser CNC machine. A continuous bending operation for producing open profiles or welded tubes with long lengths or in large quantities. Rolling

590-443: A market for bodies to fit low production, short-run and luxury cars. Custom or bespoke bodies were made and fitted to another manufacturer's rolling chassis by the craftsmen who had previously built bodies for horse-drawn carriages. Bespoke bodies are made of hand-shaped sheet metal, often aluminum alloy. Pressed or hand-shaped the metal panels were fastened to a wooden frame of particularly light but strong types of wood. Later many of

649-549: A punch and a die mounted in a press. The punch and die are made of hardened steel and are the same shape. The punch is sized to be a very close fit in the die. The press pushes the punch against and into the die with enough force to cut a hole in the stock. In some cases the punch and die "nest" together to create a depression in the stock. In progressive stamping , a coil of stock is fed into a long die/punch set with many stages. Multiple simple shaped holes may be produced in one stage, but complex holes are created in multiple stages. In

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708-628: A rolling chassis provided by an independent manufacturer. A 'conversion' is built inside an existing vehicle body. Many renowned automotive coachbuilders are based in Italy and France . In the Italian language , a coachbuilding company is called a carrozzeria , while in the French language it is called a carrosserie . A British trade association the Worshipful Company of Coachmakers and Coach Harness Makers

767-490: A series of processes in which small incremental deformation can be done in each series. Ironing is a sheet metal working or sheet metal forming process. It uniformly thins the workpiece in a specific area. This is a very useful process. It is used to produce a uniform wall thickness part with a high height-to-diameter ratio. It is used in making aluminium beverage cans. Sheet metal can be cut in various ways, from hand tools called tin snips up to very large powered shears. With

826-411: A shell or even reduced to an air intake, was or held the visual element identifying the chassis' brand. To let car manufacturers maintain some level of control over the final product their warranties could be voided if coachbuilders fitted unapproved bodies. As well as bespoke bodies the same coachbuilders also made short runs of more-or-less identical bodies to the order of dealers or the manufacturer of

885-504: A simple separate chassis (on which a custom or bespoke body could be built) mounted on leaf springs on beam axles . Unibody or monocoque combined chassis and body structures became standardised during the middle years of the 20th century to provide the rigidity required by improved suspension systems without incurring the heavy weight, and consequent fuel penalty of a truly rigid separate chassis. The improved more supple suspension systems gave vehicles better road-holding and much improved

944-546: A square/circle and welding the seam together. Their wall thickness has a similar (but distinct) gauge to the thickness of steel sheets. During the rolling process the rollers bow slightly, which results in the sheets being thinner on the edges. The tolerances in the table and attachments reflect current manufacturing practices and commercial standards and are not representative of the Manufacturer's Standard Gauge, which has no inherent tolerances. The equation for estimating

1003-492: A stiff, lightweight body. The 1961 Jaguar E-Type (XKE) used a tubular space frame–type front subframe to mount the engine, gearbox, and long bonnet/hood to a monocoque "tub" passenger compartment. Beginning with the 1960s, subframes saw regular production with General Motors ' X- and F-platform bodies, and the Astro/Safari mid-size vans. Subframes are prone to misalignment, which can cause vibration and alignment issues in

1062-400: Is a heat treatable stainless steel, but it has a lower corrosion resistance than the other grades. It is commonly used in cutlery . The only available finish is dull. Grade 430 is a popular grade, low-cost alternative to series 300's grades. This is used when high corrosion resistance is not a primary criterion. Common grade for appliance products, often with a brushed finish. Aluminium

1121-477: Is a common heat-treated structural aluminium alloy. It is weldable, corrosion resistant, and stronger than 5052, but not as formable. It loses some of its strength when welded. It is used in modern aircraft structures. Brass is an alloy of copper, which is widely used as a sheet metal. It has more strength, corrosion resistance and formability when compared to copper while retaining its conductivity. In sheet hydroforming, variation in incoming sheet coil properties

1180-567: Is a common problem for forming process, especially with materials for automotive applications. Even though incoming sheet coil may meet tensile test specifications, high rejection rate is often observed in production due to inconsistent material behavior. Thus there is a strong need for a discriminating method for testing incoming sheet material formability. The hydraulic sheet bulge test emulates biaxial deformation conditions commonly seen in production operations. For forming limit curves of materials aluminium, mild steel and brass. Theoretical analysis

1239-468: Is a process of cutting or stamping slits in alternating pattern much like the stretcher bond in brickwork and then stretching the sheet open in accordion-like fashion. It is used in applications where air and water flow are desired as well as when light weight is desired at cost of a solid flat surface. A similar process is used in other materials such as paper to create a low cost packing paper with better supportive properties than flat paper alone. Hemming

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1298-404: Is a process of folding the edge of sheet metal onto itself to reinforce that edge. Seaming is a process of folding two sheets of metal together to form a joint. Hydroforming is a process that is analogous to deep drawing, in that the part is formed by stretching the blank over a stationary die . The force required is generated by the direct application of extremely high hydrostatic pressure to

1357-445: Is also utilized as a catalyst ). These metal sheets are processed through different processing technologies, mainly including cold rolling and hot rolling . Sometimes hot-dip galvanizing process is adopted as needed to prevent it from rusting due to constant exposure to the outdoors. Sometimes a layer of color coating is applied to the surface of the cold-rolled sheet to obtain a decorative and protective metal sheet, generally called

1416-490: Is carried out by deriving governing equations for determining of equivalent stress and equivalent strain based on the bulging to be spherical and Tresca's yield criterion with the associated flow rule. For experimentation circular grid analysis is one of the most effective methods. Use of gauge numbers to designate sheet metal thickness is discouraged by numerous international standards organizations. For example, ASTM states in specification ASTM A480-10a: "The use of gauge number

1475-402: Is clear in column 3 (U.S. standard for sheet and plate iron and steel 64ths inch (delta)). The thicknesses vary first by 1 ⁄ 32 inch in higher thicknesses and then step down to increments of 1 ⁄ 64 inch, then 1 ⁄ 128 inch, with the final increments at decimal fractions of 1 ⁄ 64 inch. Some steel tubes are manufactured by folding a single steel sheet into

1534-569: Is commonly used in chemical processing equipment, light reflectors, and jewelry . Grade 3003-H14 is stronger than 1100, while maintaining the same formability and low cost. It is corrosion resistant and weldable. It is often used in stampings , spun and drawn parts, mail boxes , cabinets , tanks , and fan blades. Grade 5052-H32 is much stronger than 3003 while still maintaining good formability. It maintains high corrosion resistance and weldability. Common applications include electronic chassis, tanks, and pressure vessels . Grade 6061-T6

1593-566: Is discouraged as being an archaic term of limited usefulness not having general agreement on meaning." Manufacturers' Standard Gauge for Sheet Steel is based on an average density of 41.82 lb per square foot per inch thick, equivalent to 501.84 pounds per cubic foot (8,038.7 kg/m ). Gauge is defined differently for ferrous (iron-based) and non-ferrous metals (e.g. aluminium and brass). The gauge thicknesses shown in column 2 (U.S. standard sheet and plate iron and steel decimal inch (mm)) seem somewhat arbitrary. The progression of thicknesses

1652-452: Is generally done in multiple steps called draw reductions. The greater the depth, the more reductions are required. Deep drawing may also be accomplished with fewer reductions by heating the workpiece, for example in sink manufacture. In many cases, material is rolled at the mill in both directions to aid in deep drawing. This leads to a more uniform grain structure which limits tearing and is referred to as "draw quality" material. Expanding

1711-422: Is heated and burnt by the laser beam, cutting the metal sheet. The quality of the edge can be mirror smooth and a precision of around 0.1 mm (0.0039 in) can be obtained. Cutting speeds on thin 1.2 mm (0.047 in) sheet can be as high as 25 m (82 ft) per minute. Most laser cutting systems use a CO 2 based laser source with a wavelength of around 10  μm ; some more recent systems use

1770-423: Is metal working or metal forming process. In this method, stock passes through one or more pair of rolls to reduce thickness. It is used to make thickness uniform. It is classified according to its temperature of rolling: Spinning is used to make tubular (axis-symmetric) parts by fixing a piece of sheet stock to a rotating form ( mandrel ). Rollers or rigid tools press the stock against the form, stretching it until

1829-435: Is the open width of a V-die or wiping die. The curling process is used to form an edge on a ring. This process is used to remove sharp edges. It also increases the moment of inertia near the curled end. The flare/burr should be turned away from the die. It is used to curl a material of specific thickness. Tool steel is generally used due to the amount of wear done by operation. It is a metal working process of removing camber,

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1888-403: Is widely used in sheet metal form due to its flexibility, wide range of options, cost effectiveness, and other properties. The four most common aluminium grades available as sheet metal are 1100-H14, 3003-H14, 5052-H32, and 6061-T6. Grade 1100-H14 is commercially pure aluminium, highly chemical and weather resistant. It is ductile enough for deep drawing and weldable, but has low strength. It

1947-643: The Bugatti Type 57 , Cadillac V-16 , Packard Twelve , Ferrari 250 , Isotta Fraschini Tipo 8 , Hispano-Suiza J12 , and all Rolls-Royces produced before World War II. Delahaye had no in-house coachworks, so all its chassis were bodied by independents, who created their designs on the Type 135. For the Delahaye , most were bodied by Chapron , Labourdette, Franay , Saoutchik , Figoni et Falaschi , or Pennock . The practice continued after World War II waning dramatically in

2006-451: The 1870s, being used for shingle roofing, stamped ornamental ceilings, and exterior façades. Sheet metal ceilings were only popularly known as " tin ceilings " later as manufacturers of the period did not use the term. The popularity of both shingles and ceilings encouraged widespread production. With further advances of steel sheet metal production in the 1890s, the promise of being cheap, durable, easy to install, lightweight and fireproof gave

2065-468: The 1950s and 1960s. Rolls-Royce debuted its first unibody model, their Silver Shadow , in 1965. Independent coachbuilders survived for a time after the mid-20th century, making bodies for the chassis produced by low-production companies such as Rolls-Royce , Ferrari , and Bentley . Producing body dies is extremely expensive (a single door die can run to US$ 40,000), which is usually only considered practical when large numbers are involved—though that

2124-428: The advances in technology, sheet metal cutting has turned to computers for precise cutting. Many sheet metal cutting operations are based on computer numerically controlled (CNC) laser cutting or multi-tool CNC punch press. CNC laser involves moving a lens assembly carrying a beam of laser light over the surface of the metal. Oxygen, nitrogen or air is fed through the same nozzle from which the laser beam exits. The metal

2183-429: The backstop, more advanced machines control the position and angle of the stop, its height and the position of the two reference pegs used to locate the material. The machine can also record the exact position and pressure required for each bending operation to allow the operator to achieve a perfect 90 degree bend across a variety of operations on the part. Punching is performed by placing the sheet of metal stock between

2242-424: The curved woodwork alone called for considerable skill. Making the iron axles, springs and other metal used was the work of the “coach-smith,” one of the most highly paid classes of London workmen. The coating of the interior of the coach with leather and painting, trimming, and decorating the exterior called for specialist tradesmen with a high degree of skill. Building carts and wagons required similar skills, but of

2301-401: The final stage, the part is punched free from the "web". A typical CNC turret punch has a choice of up to 60 tools in a "turret" that can be rotated to bring any tool to the punching position. A simple shape (e.g. a square, circle, or hexagon) is cut directly from the sheet. A complex shape can be cut out by making many square or rounded cuts around the perimeter. A punch is less flexible than

2360-453: The horizontal bend, from a strip shaped material. It may be done to a finite length section or coils. It resembles flattening of leveling process, but on a deformed edge. Drawing is a forming process in which the metal is stretched over a form or die . In deep drawing the depth of the part being made is more than half its diameter. Deep drawing is used for making automotive fuel tanks, kitchen sinks, two-piece aluminum cans , etc. Deep drawing

2419-566: The main body shell on an automated line. There are generally three basic forms of the subframe: Subframes are typically made of pressed steel panels that are thicker than body shell panels and are welded or spot-welded together. Hydroformed tubes may also be used in some designs. The revolutionary monocoque, transverse-engined, front-wheel-drive 1959 Austin Mini set the template for modern front-wheel-drive cars by using front and rear subframes to provide accurate road wheel control while maintaining

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2478-469: The manual process in the late 17th century. The process of flattening metal sheets required large rotating iron cylinders which pressed metal pieces into sheets. The metals suited for this were lead, copper, zinc, iron and later steel. Tin was often used to coat iron and steel sheets to prevent it from rusting. This tin-coated sheet metal was called " tinplate ." Sheet metals appeared in the United States in

2537-410: The maximum bending force is, F max = k T L t 2 W {\displaystyle F_{\text{max}}=k{\frac {TLt^{2}}{W}}} , where k is a factor taking into account several parameters including friction. T is the ultimate tensile strength of the metal. L and t are the length and thickness of the sheet metal, respectively. The variable W

2596-411: The metal down the required amount to bend it through 90 degrees. Typically, a general purpose machine has an available bending force of around 25 tons per meter of length. The opening width of the lower die is typically 8 to 10 times the thickness of the metal to be bent (for example, 5 mm material could be bent in a 40 mm die). The inner radius of the bend formed in the metal is determined not by

2655-401: The middle-class a significant appetite for sheet metal products. It was not until the 1930s and WWII that metals became scarce and the sheet metal industry began to collapse. However, some American companies, such as the W.F. Norman Corporation, were able to stay in business by making other products until Historic preservation projects aided the revival of ornamental sheet metal. Grade 304 is

2714-734: The more important structural features of the bespoke or custom body such as A, B and C pillars were cast alloy components. Some bodies such as those entirely alloy bodies fitted to some Pierce-Arrow cars contained little or no wood, and were mounted on a conventional steel chassis. The car manufacturer would offer for sale a chassis frame , drivetrain (consisting of an engine, gearbox, differential, axles, and wheels), brakes, suspension, steering system, lighting system, spare wheel(s), front and rear mudguards (vulnerable and so made of pressed steel for strength and easy repair) and (later) bumpers, scuttle (firewall) and dashboard . The very easily damaged honeycomb radiator , later enclosed and protected by

2773-445: The most common of the three grades. It offers good corrosion resistance while maintaining formability and weldability . Available finishes are #2B, #3, and #4. Grade 303 is not available in sheet form. Grade 316 possesses more corrosion resistance and strength at elevated temperatures than 304. It is commonly used for pumps , valves , chemical equipment, and marine applications. Available finishes are #2B, #3, and #4. Grade 410

2832-428: The press contains a V-shaped groove called the die. The upper part of the press contains a punch that presses the sheet metal down into the v-shaped die, causing it to bend. There are several techniques used, but the most common modern method is "air bending". Here, the die has a sharper angle than the required bend (typically 85 degrees for a 90 degree bend) and the upper tool is precisely controlled in its stroke to push

2891-459: The radius of the upper tool, but by the lower die width. Typically, the inner radius is equal to 1/6 of the V-width used in the forming process. The press usually has some sort of back gauge to position depth of the bend along the workpiece. The backgauge can be computer controlled to allow the operator to make a series of bends in a component to a high degree of accuracy. Simple machines control only

2950-490: The related techniques repoussé and chasing have low tooling and equipment costs, but high labor costs. Coachbuilder A coachbuilder or body-maker is a person or company who manufactures bodies for passenger-carrying vehicles. Coachwork is the body of an automobile , bus , horse-drawn carriage , or railway carriage . The word "coach" was derived from the Hungarian town of Kocs . A vehicle body constructed by

3009-441: The ride experienced by passengers. Larger car dealers or distributors would commonly preorder stock chassis and the bodies they thought most likely to sell and order them for sale off their showroom floor. All luxury vehicles during the automobile's Golden Era before World War II were available as chassis only. For example, when Duesenberg introduced their Model J, it was offered as chassis only, for $ 8,500. Other examples include

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3068-412: The stock takes the shape of the form. Spinning is used to make rocket motor casings, missile nose cones, satellite dishes and metal kitchen funnels. Stamping includes a variety of operations such as punching, blanking, embossing, bending, flanging, and coining; simple or complex shapes can be formed at high production rates; tooling and equipment costs can be high, but labor costs are low. Alternatively,

3127-683: The suspension and steering components. Misalignment is caused by space between the mounting bolts and the mounting hole. Several companies in the automotive aftermarket, including TyrolSport in the US and Spoon Sports in Japan, offer solutions for subframe misalignment and movement issues. Sheet metal Sheet metal is metal formed into thin, flat pieces, usually by an industrial process. Thicknesses can vary significantly; extremely thin sheets are considered foil or leaf , and pieces thicker than 6 mm (0.25 in) are considered plate, such as plate steel,

3186-676: The thinner the metal. Commonly used steel sheet metal ranges from 30 gauge to about 7 gauge. Gauge differs between ferrous ( iron-based ) metals and nonferrous metals such as aluminum or copper. Copper thickness, for example, is measured in ounces, representing the weight of copper contained in an area of one square foot. Parts manufactured from sheet metal must maintain a uniform thickness for ideal results. There are many different metals that can be made into sheet metal, such as aluminium , brass , copper , steel , tin , nickel and titanium . For decorative uses, some important sheet metals include silver , gold , and platinum (platinum sheet metal

3245-515: The trade dealt with the timber, iron, leather, brass and other materials used in their construction. And there were many minor specialists with each of these categories. The “body-makers” produced the body or vehicle itself, while the “carriage-makers” made the stronger timbers beneath and around the body. The timbers used included ash, beech, elm, oak, mahogany, cedar, pine, birch and larch. The tools and processes used were similar to those used in cabinet-making, plus other specific to coach-making. Making

3304-424: The workpiece or to a bladder that is in contact with the workpiece, rather than by the movable part of a die in a mechanical or hydraulic press. Unlike deep drawing, hydroforming usually does not involve draw reductions—the piece is formed in a single step. Incremental sheet forming or ISF forming process is basically sheet metal working or sheet metal forming process. In this case, sheet is formed into final shape by

3363-401: Was in plate armor worn by cavalry , and sheet metal continues to have many decorative uses, including in horse tack . Sheet metal workers are also known as "tin bashers" (or "tin knockers"), a name derived from the hammering of panel seams when installing tin roofs. Hand-hammered metal sheets have been used since ancient times for architectural purposes. Water-powered rolling mills replaced

3422-525: Was incorporated in 1630. Some British coachmaking firms operating in the 20th century were established even earlier. Rippon was active in the time of Queen Elizabeth I , Barker founded in 1710 by an officer in Queen Anne 's Guards. Brewster , the oldest in the U.S., was formed in 1810. Coach-building had reached a high degree of specialization in Britain by the middle of the 19th century. Separate branches of

3481-527: Was the path taken by Rolls-Royce and Bentley after 1945 for their own in-house production. Because dies for pressing metal panels are so costly, from the mid 20th century, many vehicles, most notably the Chevrolet Corvette , were clothed with large panels of fiberglass -reinforced resin, which only require inexpensive molds. Glass has since been replaced by more sophisticated materials, if necessary hand-formed. Generally, these replace metal only where weight

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