C R E D I T S

The Fascinating World of Sheet Metal

Publisher and Editor:TRUMPF GmbH + Co.Johann Maus Strae 271254 DitzingenFederal Republic of Germany

Authors:Dr. Hubert Bitzel, Johanna Borcherdt,Jrg Mller, Frank Neidhart, Dr. Klaus Parey, Armin Rau, Sabine Riecke, Annegret Schmid,Gabriele Trentmann, Gerald Vorlnder,Klaus Zimmermann.

Graphics:Gisela Ostermann, Rainer Deuschle,Bernhard Walter

Translation:unitextTechnische bersetzungen undTechnische Dokumentationen GmbH & Co. KG, Berlin

Project coordination:Annegret Schmid

Cover photo:Udo Loster Fotostudio GmbH

Layout design:Heike Hau, Jrgen G. Rothfu

Printing:Rondo-Druck, Ebersbach-Rowlden

The original edition was published inGerman by the Dr. Josef Raabe Verlags-GmbH, Stuttgart in 1996 and entitled:Faszination Blech - Flexible Bearbei-tung eines vielseitigen Werkstoffes.

This work is copyrighted. All rights, in-cluding those pertaining to the translati-on, reprint, and the reproduction of thebook or any parts thereof, are reserved.No part of the book may be reproducedin any way, nor may it be edited or distri-buted by electronic means without theexpressed written consent of thepublisher.

The authors and the publisher affirmthat all statements made in this bookwere checked carefully and in a cons-cientious manner. Liabilities for any da-mages, direct or indirect, arising fromthe use of this book, in part or total, are excluded except where prohibited by law.

Extract of the book:The Fascinating Worldof Sheet Metal

he most important characteristic of sheet metal and plates in contrast to other rectangular forms

such as bars, strips, and flats is that itsthickness is relatively small compared toits length and width.

The difference between sheet metaland plates is determined by theirthicknesses. Sheet metal has a thicknessof less than 5.0 mm (3/16"); thickerdelivery material is referred to as a plate.Thin materials are also supplied as coils.As processing sheet metal, plates, andcoils is in many cases identical, it is oftennot necessary to take these variousdelivery forms into consideration.

The material used for sheet metal inindustry is usually always steel, but othermetals such as aluminum, copper, silver,and gold are also processed.

Characteristic properties

The thinness and the deformability ofthe metals are the aspects that makeworkpieces manufactured from sheetmetal so useful.

The thickness of the workpiece has abearing on the weight and the amountof force and energy required duringprocessing, whether cutting or forming.As sheet metal parts are thin, they arelight and therefore very inexpensive.They can be processed using suitablesheet metal processing machines quicklyand easily.

The metals used for sheet metal haveone important property they aredeformable (ductile) while retainingtheir molecular structure. The cross-section of a workpiece can therefore be

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Sheet MetalThe production and the processing of materials to create forms which cannot befound in nature are among the most significant developments of mankind.Whereas in the Stone Age naturally-occuring materials primarily wood andstone were directly processed into finished products, the beginning of theBronze Age is characterized by natural products (ores) being initially formed intoan intermediate product. The finished product was then produced in a secondstep. In nature there are very few examples of homogeneous, flat products.Woven materials, fabrics, paper and glass and, of course, sheet metal owe theirexistence to the way mankind has developed its processing techniques.

Suits of armor in Erbach Castle, Germany

T

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altered by the excertion of force withoutloss of strength. The metal is not onlydeformable when it is red-hot during theforging process, but also when it is at anormal temperature. It is also note-worthy that these metals can be rolleddown to an extremely thin form gold,for example, as little as 1/100 mm.

Sheet metal has a low rigidity in onedirection which is advantageous inmanufacturing but has its drawbacks inpractical use. It is the designers task toensure that products manufacturedfrom sheet metal can withstand thedemands placed on them. This can makeit highly desirable for the finishedproduct to be plastically deformable. Forexample, the crumple zone of a carbody absorbs a large amount of theimpact energy in a collision and thusprevents the passengers from beingseriously injured.

The merits of sheet metal

Sheet metal has a number of desirableproperties. It is, for example: flat thin, light smooth, level, even decorative can be cut or punched elastic, plastically bendable can be formed or bent can be deep-drawn can be welded easy to assemble recyclable

Many of the properties listed abovemake it clear why sheet metal is the idealstarting material for any kind of guard orcover. In these cases, the sheet metaltakes up only a small proportion of theload as, for example, in the case of a topcover.

If the stability of sheet metal isincreased by forming it in theappropriate way, the proportion of thetotal load-carrying ability is alsoincreased.

In recent decades, the use of sheetmetal in mechanical engineering hasincreased greatly. This is primarily due tothe continued development of theprocesses and the processing machinerywhich makes sheet very inexpensive toproduce. Since the Fifties it has been

possible to weld plates with a thicknessof more than 100 mm (4) perfectly.Ever since then, whole areas oftechnology, such as frame constructionhave forsaken cast-metal for weldedconstructions. The further developmentof bending techniques has led to thereplacement of integral componentsconsisting of profile sections by foldedproducts. With sheet metal products, itis easy to see the relationship betweenthe end product and the manufacturingprocess used to create it.

The range of products that can bemade from sheet metal and plates is verydiverse. It includes coverings, wall androof covers. In these cases, very thinsheets are used to cover large areas. Thecover rigidity required for use as faadesis achieved by using corrugated sheetsand trapezoidal surfaces. Apart fromtheir use as coverings, metal sheets areused to store and convey liquids andbulk goods. This includes the vastamount of beverage cans made fromthin aluminum sheet with a thickness ofless than 0.2 mm (.001") and also thehuge tanks for the oil and chemicalindustry. There are also smaller productsmade of sheet metal that do not require

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Industrial building

Plate with perforated edge

Kitchen range with extractor hood

any additional reinforcement. For thenext group of sheet metal products:housings for equipment andapparatuses, switching cabinets,furniture and vehicles such as cars,trains, ships and planes there are manycases in which the sheets not only havea covering function, but also asupportive one. This is particularlyobvious for structural supportingautomobile bodies. In the automotiveand ship building industries, one can seethe entire range of material thicknesses.Whereas the car bodies often have athickness of less than 1 mm (.05), shipsuse plates of more than 100 mm (4).The same holds true for mechanicalengineering where, for example,contact plates are made of thin sheets

and machine stands of very thick plates.Furthermore, very complex workpiecesare formed by bending and welding.

Sheets are used in mass production aswell as manufacturing individual parts.The most conspicuous mass-producedproduct is surely the automobile.

Among the single products made ofsheet metal are models for prototypes aswell as art objects which round off thisdiverse spectrum.

Manufacturing sheets

Creating sheets by hammering is amethod that goes back to antiquity. Ametal block is simply flattened to thedesired form with a hammer. Eventoday, precious pieces are usuallyhammered to form small sheets.

A 2.5 m wide, mobile bed was foundin the grave of a Celtic prince in the townof Hochdorf near Stuttgart. The bed hadbeen constructed from thin bronzesheets more than 2500 years ago. Thesheets were reinforced at the edges withan inserted wire and an appropriateshaped form. This type of edgereinforcement is still common today.

Hammering by hand was replaced bygradual, mechanical pressing. Leonardoda Vinci designed a type of roll presspress which formed spring bands to thedesired size. Blueprints are still on handfor a device for rolling strips.

Approx. 200 years ago, thetechnique of rolling sheets and stripswas introduced. It gained acceptance inthe last century.

Rolling is a process in which a startingblock (slab) is pulled through a gap bytwo powered rollers which reduce theslab thickness by approx. 20 30 %. Thisprocess has two variants: hot and coldrolling. Hot rolling is the process ofrolling red-hot metal to produce thicker

sheets and plates. Thin sheets, on theother hand, are cold rolled because theydissipate heat so quickly that theglowing temperature cannot bemaintained. Cold rolling produces moreprecise tolerances as well as harder andbetter surfaces.

After rolling, thicker sheets are cut tothe desired formats with shears or flamecutting machines from runs which areup to 40 m in length. Thinner strips arecut lengthwise with slitting lines intosmaller strips or into sheets using cut-to-length lines.

Rolling is not only limited to themanufacture of sheets and strips. Rods,profile sections, wires and pipes can alsobe manufactured with the appropriaterolling mills.

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2500 year old bed made of bronze sheets

A river of steel

Rolling mill by Leonardo da Vinci

Selection criteria for sheetdimensions

To determine the most suitable sheetmetal for a particular workpiece, thegeometric dimensions and the mostpractical material should be chosen. Thefollowing criteria give an indication ofthe wide variety of options:

Thickness: In addition to mm, thematerial thickness of sheets is alsomeasured in inches and gauges incertain countries. The selection ofnominal thicknesses for thin sheets is sovaried that the right sheet thickness isavailable for just about any conceivabletask.The rolling of the two sheets is soamazingly precise that only very slightdifferences in thickness are produced.

These thickness tolerances depend onthe sheet thickness, the sheet format,the material and the manufacturingform. They are agreed upon with thesheet manufacturer according to thedelivery conditions. The maximumdeviation from a level surface must alsobe specified. The flatness of sheets isnecessary for trouble-free operationduring processing.

Formats and delivery formats: Themaximum width of sheets depends onthe width of the roller path. You can findsheets up to 4 m wide and 10 m long inthe delivery lists from sheet metalsuppliers. The most popular sheetformats are between 1000 x 2000 mm,and 1500 x 3000 mm, in North Americabetween 3 x 6 and 5 x 10.

22.5

3m

1m5' 4' 3'

1.251.5

thickness up to 150 mm (6")

with up to 4 m

length up to 10 m

6'8' 10'

diameterup to 2,3 m

thickness up to 10 mm (3/8")

with up to 2 m (96")

Strips in the form of a rolled up coil canbe several 100 meters long. The coilshave a maximum width of 2 m (96"), amaximum diameter of 2.3 m and aweight of up to 40 tons (50,000 lbs.).The thickness of the strips is usually lessthan 3 mm (1/8), but coils consisting ofstrips with a thickness of 10 mm (3/8")are also available.

Special forms of sheet metal

Aside from the usual delivery form as ahomogeneous sheet of metal with adouble-sided, flat, smooth, unprocessedsurface, there are a series of specialfeatures. This means the user does not have to ask the manufacturer to make a modification for a particularapplication.

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INCH

.18

.16

.14

.12

.1

.08

.06

.04

.02

26 24 22 20 18 16 14 12 10 8 6

4,0

3,5

3,0

2,5

2,0

1,5

1,0

0,5

G A U G E

HotRolledColdRolled

mm

4,5

Commercial graduations inthickness in mm

Commercial sheet formats

Commercial coil dimensions

Sheets, plates and coils

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Sheets made of various materials(for example, mild steel,galvanized steel, aluminum,copper, bronze)

Sheets with a fine and coarsestructured surface(for example, stainless steel with aground surface, high-grade steelwith a foil cover, chequer plate,bubble pattern, and rib pattern)

Sheets with a profile(for example, trapezoidal sheet,corrugated sheet, sheet tube)

Profiled sheets, corrugated sheets andflooring plates: Particularly for use asfacade and roof coverings, sheets aredelivered which have been rolled in sucha way that their cross sections have awave-like form or consist of trapezoidslined in a row. These sheets have aconsiderably higher level of rigidity thanflat ones.

If sheets are used as floor coverings especially for stairs, steps, and catwalks they must have a nonslip surface.These are provided by a chequer on oneside which is raised a few millimeters.

Rhombic passes, formed by crossingtwo layers of angular ribs and also lens-shaped raised sections have proventhemselves to be effective.

Design sheets have a surface which isnot as structured as flooring plate. Thepattern is more for appearance andreplaces in many cases the coat of paint.

Tailored blanks: In contrast tohomogeneous sheet metal which hasthe same thickness and material quality,there have been efforts in recent years toproduce single sheets with variousthicknesses and levels of quality. Thesetailored blanks are formed by weldingdifferent sheets together. Thesecustomized sheets make it possible togradually modify the sheet thickness tothe load it will be exposed to. Putanother way, sections subject to agreater load are made thicker.

Pre-working: Many sheet metalsuppliers are willing to prepare thesheets so that they are easier to use bytheir customers. Preworking means notonly are the sheets tailored to thedesired format, but also ground,rounded off or coated with a foil toallow non-scratch processing.

Selecting criteria for sheetmetal materials

The large selection of materials availableare not exhausted for workpieces madeof sheet metal, because the demands onthese pieces are normally not all thatvaried.

Whereas strength and hardness arethe most important selecting criteria formachine parts, it is the workingproperties and non-corrosivecharacteristics that are of primaryimportance for metal sheets. In manycases, the material is selected less for itsload resistance than for its suitability fora particular process. Cutability forpunching, flame cutting, laser cutting,water jet cutting as well asdeformability for deep drawing, rollforming, pressing, bending and weldingare all factors to be considered.

Sheet metal parts are highly corrosivedue to their large surfaces and also less

resistant than massive parts. Apart fromswitching to stainless steel, light metalalloys or applying an anti-corrosive coat,non-corrosive sheets can also beobtained.

Cold-rolled sheet metal: With thesesheets, fracture strain A 80[%] for colddeformability is more important thantensile strength Rm [N/mm2]. For thisreason, two different properties sufficeto satisfy the various demands in sheetmetal working: commercial quality anddrawing quality.

Hot-rolled plates: For hot-rolled thickersheets, strength and weldability are inmany cases more important propertiesthan deformability.

Conventional mild steel with astrength between 370700 N/mm2 ispreferred.

Stainless steel: The main field ofapplication for stainless steel is the foodprocessing industry. Stainless steel costsmany times more than mild steel and isconsiderably more difficult to process.Due to its alloy components (more than12% chrome), it offers the guarantee ofnon-corrosiveness obviating the needfor additional protective measuresagainst corrosion superfluous. Herealso, only a few sheet metal propertiesare needed.

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EN10130 RM A80 DIN ASTMType of steel [N/mm2] [%] 1623

FeP01 290 - 410 28 St12 A366FeP04 270 - 350 38 St14 A620

ild steel (Cold rolled steel)M

Thin sheets used in automotive body construction

The basic material for anti-corrosivesheet metal is steel which has beencovered with a metallic protective layer.The layer is applied either by hot-dipping, plating, or electroplating.Electrogalvanized sheet metal is themost important of the non-corrosivesheet metals.

Example of ordering sheet metal

The ordering code contains thegeometric dimensions with theadditional demands for edge quality,levelness, and side straightness as wellas the code designation according to thestandards or terms of delivery.

The ordering code for a sheet madefrom steel of Fe P06 quality with thedimensions 1200 mm x 2500 mm, witha thickness of 0.8 mm, whose leveltolerances should be limited (FS), whosesurface is smooth (g) and is, at least onone side, free of pores, drag lines, wartsand scratches (B) would be:sheet metalEN 10131 0.8 x 1200 x 2500 FS

steelEN 10130 Fe P06 Bg.

If no special characteristics are requiredin reference to the standard values, thetypical dimensions (thickness x width xlength) together with the materialquality suffice:sheet 18Ga x 4" x 8" CRS oiled SS 304

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DIN 17441 AISI/SAE1.4016 X 6 Cr 17 4301.4310 X 5 Cr Ni 18 10 304/304L1.4541 X 6 Cr Ni Ti 18 10 3211.4571 X 6 Cr Ni Mo Ti 17 12 2 316Ti

The model type and surface structure are determined in accordance with country-specific standards such as DIN 17440 or ASTM A 240.

tainless steelS

Plates used in mechanical engineering

Stainless steel in a chemical installation