asm - extruded products

CHAPTER 2

Extruded ProductsGunther Sauer*

THE HOT-WORKING PROCESS extrusionis used to produce semifinished products in theform of bar, strip, and solid sections as well astubes and hollow sections. The high mean com-pressive stresses in the deformation zone of thecontainer enable materials to be worked thatcannot be processed into semifinished productsby other hot-working processes, for examplerolling, because of their limited workability. Theextrusion process also enables semifinishedproducts to be produced from powder metal-lurgy-based materials, composite materials, andthe production of semifinished products fromclad composites with material combinations in-cluding aluminum/copper and aluminum/steelusing the cladding process. Finally, the sheath-ing of electrical cables with lead or aluminumalloys using the transverse extrusion process hasbeen a standard process for a long time, as hasthe production of multicore solders with inte-grated flux cores using the same process.The pushing of the material being extruded

through the shape-forming aperture of the extru-sion die enables cross-sectional shapes to be pro-duced that cannot be manufactured by any otherhot-working process. The favorable deformationconditions with nonferrous metals such as tinand lead alloys as well as magnesium and alu-minum alloys with good welding properties andworking temperatures that can be withstood bythe tool materials also enable the billet to be di-vided into several metal streams, and then re-welded in the shape-forming region of the ex-trusion die to form tubes and hollow sections.The production of hollow sections is one of the

*Extruded Products from Materials with a Working Temperature Range of 600 to 1300 !C, Martin Bauser

main applications of extrusion. This process canalso be used for certain copper alloys; however,the materials used for the extrusion tooling can-not withstand the thermo-mechanical stresses.Billet-on-billet extrusion enables coiled tubes oflong length to be produced, for example, alu-minum alloy heat exchanger tubes and tin andlead alloy multicore solders.The extrusion process generally produces a

semifinished product close to the finished sizewith materials with working temperatures up to600 !C. This occurs in one production step incontrast to other processes used to form semifin-ished products. Therefore, the design of thecross section of the semifinished product canpractically ignore any limitations associatedwith subsequent processing operations. Themost suitable cross-sectional geometry can befreely selected for the specific application. Sim-ple matching of the cross-sectional geometry ofthe extrusion to the static, dynamic, and geo-metric requirements combined with the widerange of joining methods in assembly character-ize the high functionality of the products pro-duced by this working process.

2.1 Tin and Lead ExtrudedProducts with a DeformationTemperature Range of 0 to 300 !C

Tin alloy extruded products are mainly softsolders with or without flux cores for use in elec-trical engineering and electronics. Tin alloys aresignificantly more common than are lead alloys.

Extrusion: Second Edition M. Bauser, G. Sauer, K. Siegert, editors, p 9-58 DOI:10.1361/exse2006p009

Copyright © 2006 ASM International® All rights reserved. www.asminternational.org

10 / Extrusion, Second Edition

Fig. 2.1 Soft solder with one or more flux cores (tube solder),extruded and drawn to the finished dimensions and

coiled on plastic spools. Source: Collin

Fig. 2.2 Extruded sections and tubes in lead base and tin al-loys for use as anodes for the electrochemical coat-

ing, supply tubes for aggressive media, materials for seals andradiation protection, etc. Source: Collin

They are produced on horizontal presses anddrawn, coiled, or wound to the customers’ de-sired finished sizes on multispindle wire draw-ing machines as shown in Fig. 2.1. The produc-tion processes are described in section 5.3. Otherextruded products are anodes used for electro-chemical plating with tin, for example, tin plat-ing for corrosion protection. Tin alloy extrudedproducts are also used in the manufacture ofchemical equipment.Lead alloy products have lost a large part of

their market since World War II because of thetoxic properties of these alloys. Even in the1950s, extruded lead alloys were still used forwater supply pipes up to the fittings on sinks.These materials were also used for extruded wa-ter waste pipes. This has changed completely.Lead alloys may no longer come into contactwith food products because they can form verypoisonous lead salts. Drinking water counts as afood and, therefore, lead drinking water pipesare no longer permitted. Nevertheless, lead al-loys offer a range of advantages that make al-ternative materials difficult or even impossibleto find. Lead alloys have good resistance tofluoric and sulfuric acids as well as phosphoricacid, ammonia, chlorine, and soda. They aretherefore useful alloys for the chemical industry.

The high density makes lead alloys particularlysuitable for radiation and noise protection. Goodworkability combined with low melting pointsmeans that lead alloys are also used for the man-ufacture of soft solder, which is described in sec-tion 5.3. Lead alloys, similar to tin alloys, arealso suitable for the production of customshaped anodes as shown in Fig. 2.2 for electro-chemical plating. An example is the approxi-mately 20 lm thick and soft running surface inplain bearings such as bearing shells and bushes.Although the use of specific lead alloys for theproduction of cable sheaths cannot be classifiedas environmentally harmful, the cable industryprefers alternative plastic and aluminum-basematerials. High-voltage cables are still sheathedin lead. Spacers for double glazing (Fig. 2.3) arealso extruded from lead alloys. Fishing nets andcurtains are usually weighted with lead linesproduced by horizontal extrusion. Some exam-ples are shown in Fig. 2.3.Lead alloys can be made relatively resistant

to corrosion by the addition of tin. They can alsobe recycled relatively easily. However, the en-vironmental political pressure will affect the cur-rent applications because of the toxic propertiesof this material.

Chapter 2: Extruded Products / 11

Fig. 2.3 Extruded solder with several flux cores, leadsheathed cable, and window spacer sections in lead

alloys for double glazed windows, as well as lead lines for fishingnets and curtain weights. Source: Collin

Fig. 2.4 From left to right: Section in MgAl2Zn for the pro-duction of pencil sharpeners, two sections in

MgAl3Zn for warp knitting machine, and test arm sections fordisc magazines. Source: Fuchs-Metallwerke

2.2 Magnesium and AluminumExtruded Products with a WorkingTemperature Range of300 to 600 !C

2.2.1 Magnesium Alloy Extruded ProductsMagnesium alloys are light materials with

useful mechanical properties. Their density ofapproximately 0.0018 kg/m3 is about 36% lessthan that of the aluminum alloys. The Young’smodulus (E) is approximately 45 GPa and,therefore, about 65% of the E-modulus of alu-minum alloys. For this reason, they are, in prin-ciple, more interesting than aluminum alloys asa construction material for light components.However, the corrosion resistance ofmagnesiumcomponents is not usually as good as that of alu-minum components. They, therefore, have to begiven more surface protection. The corrosionsensitivity of magnesium alloys can be loweredsignificantly by reducing the trace element con-tent of copper, iron, manganese, and nickel intothe ppm region. The corrosion behavior of high-purity magnesium alloys approaches that of alu-minum alloys. This has considerably increasedthe interest in magnesium alloys as constructionmaterials. However, the mechanical behavior ofmagnesium components is very directional de-

pendent because of the hexagonal lattice struc-ture. In addition, any partial cold working ofmagnesium components, as is necessary, for ex-ample, for the aluminum alloy side door beamin Fig. 2.24, in the section “Passenger Cars,” ispractically impossible because of this hexagonallattice structure. Magnesium alloys naturallyhave good machining characteristics. Unlikealuminum alloys, they do not need any chip-breaking alloying additions such as lead and bis-muth. Consequently, extruded semifinishedproducts are eminently suited to the productionof turned components including ones in dailyuse, for example, pencil sharpeners. A typicalprofile can be seen in Fig. 2.4 [Fuc 96]. In thepast, the market for extruded magnesium alloyproducts was limited in spite of the products’good properties, in particular, their low density.The reason for this is both the lattice-relatedpoor cold-working properties, and the hot-work-ing properties that are very alloy dependent. Themain application for magnesium alloys is, there-fore, still cast components. The most well-known application is the engine and gearboxhousing used after WorldWar II in the air-cooledflat twin engine in the Volkswagen Beetle.Basically, magnesium products are used

where the weight saving, e.g., components witha low mass, has high priority. The main areas ofapplication are automobile and machine manu-facture. The extruded products shown in Fig. 2.5and 2.6 are suited primarily for machine com-ponents subjected to high acceleration and brak-ing, for example, in textile machine components[Fuc 96]. These products are also used in theaerospace industry and in military applications.


Fig. 2.5 Extruded section in MgAl3Zn for textile machines.Source: Fuchs-Metallwerke

Fig. 2.6 Hollow section in MgAl3Zn for the external rotor ofa turbocharger for automobile engines. Source:

Fuchs-Metallwerke

Magnesium alloys are being developed fur-ther because of their suitability for light com-ponents with the intention of achieving higherstatic and dynamic mechanical properties aswellas improving the working properties [Tec 96/97/98, Gar 93]. Interest in magnesium alloy com-ponents is increasing, particularly in the auto-mobile industry.In the past, hot-worked semifinished products

in the form of magnesium alloy sheet and ex-

truded products were used to a significant degreein the period before World War II. Complete fu-selages in hot-rolled and section-reinforcedmagnesium sheets were produced for small air-craft [Bec 39]. Bus trailers were manufacturedalmost entirely from hot-worked magnesium al-loys, including a welded frame of extruded mag-nesium tubes clad with magnesium sheet [Bec39]. Welded seat frames for passenger aircraftwere made from extruded magnesium tubes.The increasing interest by the automobile in-

dustry in light extruded products in order to saveenergy by reducing vehicle weight has resultedin increasing examination of extruded semifin-ished products in magnesium alloys. This willgain in importance if the further development ofthe magnesium alloys results in higher values ofstatic and dynamic strength and improved work-ing and corrosion properties. It can, therefore,be assumed that magnesium alloys will also beused to an increasing extent for load-carryingcomponents as well as safety components,which require a good proof stress and elonga-tion. Magnesium alloys are, moreover, as easilyrecycled as aluminum alloys.The extrusion of magnesium alloys is de-

scribed in section 5.5.

2.2.2 Aluminum Alloy Extruded ProductsThe main application of the hot-working pro-

cess extrusion is in the general production ofbars, tubes, and wire in aluminum alloys and, inparticular, the manufacture of aluminum sec-tions. No other material is used as a semifinishedproduct to the same extent in practically all areasof technology. Acceptable materials propertiesand modulus of elasticity, weight saving fromthe low-density, good surface quality, good di-mensional accuracy and minimum subsequentmachining, and ease of recycling make alumi-num alloys both economically and environmen-tally interesting. These properties, as well as thelargely unrestricted shape of the cross-sectiongeometry, are the basis for the trend to the de-velopment of ever more functional componentswith good appearance and corrosion resistance.The reason for the predominance of alumi-

num profiles in extrusion is due to the moderateworking temperatures of the aluminum alloys.The extrusion tooling can then withstand thethermo-mechanical stresses. In general, theworking temperature of aluminum alloys is be-low the annealing temperature of the hot-work-ing tool steels normally used to manufacture alu-


Fig. 2.7 Large sections produced from containers with a circular bore on the 98,000 kN direct extrusion press in Singen. Adaptedfrom Alusuisse

minum extrusion tools. This has played adecisive role in the development of the designof extrusion tooling for aluminum profiles. Verydemanding aluminum profiles can now be pro-duced. In recent years, the development of ex-trusion tools for the production of large profileshas been particularly successful.Large profiles are used today in almost all ar-

eas of industry. In Europe alone there are fourlarge extrusion presses with press powers of72,000 to 100,000 kN used to produce them.Standard solid and standard hollow sectionswith a circumscribing circle diameter of approx-imately 600 mm can be produced from 650 mmround containers on the 98,000 kN direct extru-sion press operated by Alusuisse in Singen (Ger-many) (Fig. 2.7). Solid flat sections with maxi-mum dimensions of 800 by 100 mm (width byheight) and flat hollow sections with a maximumsize of 800 by 60 mm can be produced from the

same round container by using spreader tech-niques. West European aluminum extrusionplants today can produce extruded sections rang-ing from 10 g/m to 130 kg/m. The section “Ex-trusion of Semifinished Products in AluminumAlloys” describes the extrusion processes usedtoday for aluminum alloys.The large profile technology was first devel-

oped in the second half of the 1970s for the con-struction of railway rolling stock. Until then, thetechnical advantages of aluminum aroused someinterest in its use as a construction material, butthe classic method of construction of railcarbody shells using sheet and small extruded pro-files could not compete with the proven con-struction material steel. A light steel design ofthe body shells was about 50% cheaper than acomparable one made from aluminum alloys.The light steel construction was, therefore, pre-ferred. This changed with the introduction of


Fig. 2.8 Shell of a type MF77 carriage of the Paris Metro, self-supporting in welded large section technology (Alsthom Atlantique/Alusuisse, 1977/1981) manufactured in sections from the age-hardened material AlMgSi0.7. a, Multifunctional longitudinal

stringer; b, construction of the carriage body in the roof longitudinal stringer region; c, weld joint geometry between the individualextruded sections; 1, multifunctional longitudinal stringer; 2, section in roof region with extruded weld preparations; 3, longitudinalstringer to ensure adequate stiffness of the floor group; 4, door mechanism; 5, rainwater gutter extruded on section 1; 6, door seallocation extruded on section 1; 7, roof closure section; 8, roof internal cladding; 9, floor section with extruded legs for the welded jointsas well as extruded center locations; 10, floor group sections with extruded slip seating for tolerance equalization; 11, section view ofthe floor sections with extruded locations for bolt heads. Source: Aluminium Zentrale

large profiles the length of the rolling stock thatcould be automatically welded to each other.The assembly cost of the railcar body shellscould be reduced to an extent that not only com-pensated for the higher material cost of the alu-minum but also reduced the total cost of the alu-minum wagon by approximately 30% of that ofthe steel wagon [Wis 92, Cor 95].Aluminum designs using large profiles that

simplified assembly then started to competewithsteel. Today, aluminum large profile technologyhas become the economic solution in manybranches of technology. Large profiles enableseveral fabricated classic components to be re-placed. Extruded profiles can be supplied as in-tegral components ready for installation. Largeprofiles not only can replace several classic com-ponents but also, in addition to their static anddynamic functions, take on additional functionsin addition to the overall function with the min-imum of additional material as shown in Fig 2.8,which depicts cross-sectional views of a carriageof the Paris Metro [Alz 85].The mechanical properties of the aluminum

alloys used for the production of large aluminumprofiles are adequate for most applicationswhere good design enables the profile geometryto be adequately dimensioned. Nevertheless, dif-ficult to extrude and, to some extent, moderatelydifficult to extrude aluminum alloys (those with

a higher alloy content) do not offer the sameprofile geometry options as the low alloyedand easily welded aluminum alloys such asAlMgSi0.5 and AlMgSi0.7.Figure 2.9 shows a body shell of the Paris

Metro type MF 77 utilizing welded large profiletechnology. The carriage cross section is shownin Fig. 2.8, together with some of the large pro-files necessary for its construction. Figure 2.10shows the right longitudinal rib needed to stiffenthe floor frame of the carriage of the San Fran-cisco Metro in the alloy AlMgSi0.7 on the run-out table of the 98,000 kN direct press in Singen,Germany.Since the introduction of the integral con-

struction utilizing large section technology, alu-minum designs can increasingly compete withsteel designs in spite of the higher material costof the aluminum. The specific properties of alu-minum alloys play a role here including the lowE-modulus of the various alloys and their lowdensity. Whereas the E-modulus of aluminumalloys can be assumed to be approximately 70GPa, that of steel is approximately 210 GPa,three times as high. At the same time, the alu-minum designs can be given the same stiffnessas steel designs to avoid unacceptable bendingor vibrations with significantly lower weightsbecause of the low density of 2.7 g/cm3. In ad-dition, the elastic properties of aluminum de-


Fig. 2.9 Assembly of an aluminum MF77 type shell for theParis Metro using welded large section technology

together with some large sections ready for assembly. Source:Alusuisse

Fig. 2.10 Large section in the aluminum alloy AlMgSi0.7 foraluminum carriages for the San Francisco Metro

using large section welded technology on the runout table of the98,000 kN direct extrusion press at Alusuisse Singen. Source:Alusuisse

signs offer significant advantages. Aluminum al-loys have significantly higher elastic or energyabsorption capacity relative to steel because oftheir low E-modulus. This is an advantage thatshould not be undervalued for aluminum designssubjected to impact loads, for example, in rail orroad transport vehicles.

2.2.2.1 Transport ConstructionRolling Stock. Efficient low-weight rolling

stock has always been of interest to railway op-erators. Low weights provide higher load capac-ities with lower energy consumption and enablehigher vehicle accelerations when starting andhigher vehicle deceleration on braking, as wellas a reduction in rail wear. These advantages aremainly utilized by local traffic with its manystops, e.g., underground trains, but also by longdistance traffic, in particular, high speed railtraffic.Toward the end of the 1920s, the transfor-

mation of weight reduction in rolling stock re-sulted in the replacement of steel internal fittingsby fittings made in aluminum alloys, initially inpassenger carriages. However, in 1934, the Bal-timore and Ohio Railroad Company, at that time

one of the largest North American Railway com-panies, had built for them, excluding the con-ventional locomotive design, an aluminum ex-ample of the semistreamlined steam-powered“Royal Blue,” traveling between Chicago andSt. Louis [Hug 44]. Only the wheel trucks, cou-plings, and buffers of the eight passenger carswere made in steel, all other components fromalloys of the alloy group AlCuMg. Long ex-truded profiles were used for the load-carryingcomponents of the car underframe. Even the col-umns of the side walls were made of extrudedprofiles, which were also used for the necessarystiffening in other places in the carriage. Formedsheets in the same aluminum alloy were used forthe cladding of the carriage walls, for the traincar roof as well as for the floor.Sections and sheet were joined together with

rivets and arc welding. In addition, the internalfittings of the carriage, for example, the tablesand seats in the dining car, also were made fromaluminum alloys. The eight carriages built com-pletely from aluminum had a total weight of 350metric tons in contrast to the identically con-structed steel carriages with 650 metric tons, i.e.,54% of the weight of the steel carriages.


Fig. 2.11 Diesel power car of the Trans Europa Express (TEE) on the Rhine section

Fig. 2.12 Carriage body of the Trans Europa Express (TEE) inriveted and spot-welded ALMgSi sheets with lon-

gitudinal and transverse stiffeners in extruded sections of thesame alloy in the heat treated temper

The desire to reduce the weight of rollingstock by using aluminum alloys continued to de-velop after World War II. In the second half ofthe 1950s, the German Rail Company operatedseveral of the advanced for the time fast diesellocomotives designated VT 11.5 with a maxi-mum speed of 160 km/h for the lucrative long-distance service.The carriages were made from riveted and

spot-welded AlMgSi1 sheets with longitudinaland transverse stiffeners in extruded solidAlMgSi1 sections. Both types of semifinishedproducts were used in the age-hardened temper.Only the main transoms in the under frame ofthe carriage as well as the wheel trucks and cou-pling carriers were made in St52 steel as well asthe coupling system. Figure 2.11 shows thisdiesel train on the Rhine section, and Fig. 2.12shows a cross section of the conventionally builtand thus correspondingly expensive carriage.The multiunit railcar train shown in the pho-

tographs with its design that is still modern bytoday’s standards traveled as the Trans EuropaExpress (TEE) in Inter-European long-distancetravel. It consisted of five carriages as well asthe two power cars, each with a diesel engine,at the front and the back. The basic concept ofthis diesel multiunit railcar, two external powercars with the carriages in between, is practicallythe basis of the German InterCity Express trainsICE1 and ICE2 used today.During the postwar decades, the European na-

tional railways built their rail networks initially

for train speeds up to 200 km/h, speeds thatcould be achieved using electric locomotives. Inthe context of the further technical developmentof the wheel/rail system, the tracks have beenprepared in the past 10–15 years for significantlyhigher speeds. In the near future, the Europeanrailways are targeting future high-speed rail traf-fic with speeds of 350 km/h (220 mph). Largeadvances along this path have been made by theFrench national railway SNCF with its TGV,


which set a world record of 515 km/h (320 mph)on test runs. In the next 20 years in Europe, acertified rail network for high-speed trains withmultiple current systems and corresponding sig-nal and control systems will develop in Europeto allow inter-European long-distance trains totravel the national rail networks. These stretchesare operated for inter-European long-distancetrain travel with train concepts that do not followthe previously conventional train system of “alocomotive with carriages.” One example is theEurostar, a special design of the TGV with amultiple current system that can travel betweenParis and London in three hours through theChannel Tunnel. The ICE3 of the DB follows asimilar concept.From this perspective, the European railway

operators have a vital interest in trains with thelowest possible weight for the high-speed railnetwork as described previously. Low weightsminimize the energy requirements for poweringthese trains as well as the wear of the tracks andpermit high accelerations when starting and de-celerations on braking.The big breakthrough for the economical ap-

plication of aluminum alloys in carriage con-struction was the development of the large pro-file technology in the 1970s by Alusuisse. Thisenabled rolling stock to be entirely and eco-nomically produced from aluminum at a signifi-cantly lower cost than comparable rolling stockin steel lightweight construction. This involvesthe use of easily extruded, relatively corrosioninsensitive, and easily age-hardened aluminumalloys such as AlMgSi0.5 and AlMgSi0.7, with-out which the very demanding cross-sectionalgeometries of the large profiles could not be pro-duced. These extrusion alloys also provided sig-nificant freedom in the design of the cross sec-tion to match the strength needed in thecomponent. Until now, this could not beachieved with moderate to difficult to extrudealloys used previously in the manufacture ofrolling stock. Modern concepts were also devel-oped for the steel lightweight designs of rollingstock, but these could not significantly reducethe price advantage of the aluminum large pro-file technology [Aug 77, Wis 92]. The rollingstock produced from welded large profile tech-nology also offers weight advantages over thoseproduced from the high-strength steels. Boththese factors resulted in the extensive applica-tion of the aluminum lightweight constructionincorporating the large profile technology in Eu-rope and the United States in the 1980s [Dav 79,

Ing 91]. Further development resulted in interestin the aluminum large profile technology for themultiunit railcars for the high-speed rail traffic.In this period, the percentage of rolling stockproduced using large aluminum alloy profiletechnology increased out of proportion. At thestart of the 1970s, it was approximately 5% buthas now increased to over 60% [Ing 91].Whereas the French high-speed train TGV of

the SNCF with its respectable power and provenability over several years was manufactured insteel, the German Railway decided to build its280 km/h (175 mph) high-speed trains InterCityExpress 1 (ICE1) and InterCity Express 2 (ICE2),as well as the 330 km/h InterCity Express 3(ICE3), and the 230 km/h InterCity Express T(ICET), basically using self-supporting weldedlarge aluminum profile technology. The only ex-ception was the power cars of the trains ICE1and ICE2, which were manufactured in steel toensure that the driven four axles per power carcould apply sufficient normal force onto thetrack to obtain the torque needed to achieve highacceleration and deceleration.This, however, results in high track loading

because each wheel truck of these power carsplaces a load of 40 metric tons onto the rails.Throughout Europe, however, the track can onlybe loaded to a maximum of 34 metric tons perwheel truck. For this reason, the two high-speedtrains ICE1 and ICE2 cannot use the inter-Eu-ropean rail network. This, however, changedwith the introduction of the high-speed trainICE3, which in contrast to the power car train isdesigned as a multiunit train; i.e., the drivenaxles are spread along the entire train with everysecond axis being driven. These trains apply aload less than 34 metric tons weight on the trackper wheel truck and are therefore suitable forparticipation as multisystem trains for the Inter-European traffic [Tas 93]. The InterCity ExpressT (ICET) is in certain ways a special design ofthe ICE3 fitted with tilting technology devel-oped in Italy. With this design, the multiunittrain can travel around curved rails with highspeed. Figure 2.13 shows an example of theICE1 framed with a schematic diagram of theextruded profiles for the floor group, the longi-tudinal member of the floor group, and the con-necting edge wall profile of the left side of thepassenger carriage. The joint aids visible on thesection corners in Fig. 2.13 for the longitudinaljoining of the extruded sections are of interest.Finally, Fig. 2.14 describes the design of the

passenger carriage with all the large profiles for


Fig. 2.13 High-speed ICE1 of the Deutsche Bahn AG framed by the large sections of the carriage cross section shown in Fig. 2.14.Source: Alusuisse

the left half of the carriage. In addition, Fig. 2.15shows a view of the design of the passenger car-riage of the high-speed trains ICE2 and ICE3.Other European national railways, for exam-

ple, Denmark, England, Italy, and Norway, aswell as Spain and Sweden, have learned thevalue of the self-supporting aluminum large pro-file technology in welded designs for high-speedtrains as well as intercity passenger carriagesand intercity rail cars. This technology has, forexample, been used for building the 250 km/h(155 mph) high-speed Advanced PassengerTrain of British Rail and the 300 km/h (185mph) ERT 500 of the Italien Ferrovie dello Stato(FS). The French TGV Duplex, a double decker,new high-speed train of the SNCF, will be man-ufactured using welded aluminum large profiletechnology to control the track loading.Self-supporting large profile aluminum tech-

nology is used not only for high-speed trainsrunning on rails. The carriages of the trackguided fast magnetic levitation Transrapid, witha maximum speed of 500 km/h (310 mph) arebuilt using the self-supporting aluminum largeprofile technology in a bolted design [Mil 88].The prototype is shown in Fig. 2.16. This assem-bly method is described in the section “BusManufacture” later in this chapter.Naturally, thought has been given to reducing

the wagon weight in rail freight transport with

the aim of reducing transport energy costs. Fora long time, there has been increasingly rigorouscompetition with other methods of transport, in-cluding road transport. Initially, this involved in-creasing the load capacity of the freight wagonby using individual, usually movable, aluminumalloy components for the same wagon axle load.Consideration was then given to significantlyimproving the handling of the construction ele-ments. Sliding roofs, folding roofs, as well assliding doors and shutters, were manufacturedfrom aluminum sheet and reinforced with ex-truded sections by the German railway, DB, aswell as the Swiss Federal Railway, SBB. Withtime, complete wagon bodies also were builtfrom aluminum alloys. The structure of thesewagons consisted of roll formed 1.5 to 2.0 mmthick AlMg3 sheets reinforced with AlMgSi0.5extruded sections, apart from the under frameand the vertical end wall columns, which weremade in steel. In addition, the aluminum con-struction offers not only the advantage of weightreduction but is also maintenance friendly, i.e.,in contrast to steel designs, no painting is neededbecause of the corrosion resistance of the alu-minum alloys used.Tilting sidewalls on open goods wagons for

specific transport applications are manufacturedfrom AlMgSi0.5 and AlMgSi0.7 extruded pro-files, as shown in Fig. 2.17. These sidewalls can


Fig. 2.14 Passenger carrier design on the high-speed train ICE1 of the Deutsche Bahn AG with the large sections of the left carriagesection. Source: Alusuisse

be highly loaded and do not require any surfaceprotection because of the corrosion resistance ofthe aluminum alloys.The focal point of European rail transport is

mixed cargo transport where the loading spaceof a wagon is more important than the load-carrying capacity. Consequently, the applicationof aluminum alloys is usually limited tomovablecomponents as described previously. Bulk goodstransport by rail has only a limited role in Eu-rope.This differs in other countries, including

Australia, Canada, South Africa, and the UnitedStates, with, for example, rich surface reservesof coal and minerals. The extraction site is usu-ally a long distance from the processing plantso that bulk goods have to be transported over

large distances. This process is usually carriedout using rolling stock with the optimum loadcapacity. The optimum storage capacity of thesewagons can be achieved by using self-support-ing welded aluminum large profile technology,which makes them particularly economicalcompared with wagon designs in steel. Figures2.18 and 2.19 show an example of a coal silowagon built with aluminum large profile tech-nology. The sidewalls as well as the chassis ofthis coal silo wagon consist mainly of largeextruded profiles in the aluminum alloyAlMgSi0.7 with large format sheets ofAlMg2.7Mn in the floor area. The assembly ofthe silo wagon involves the use of the sameautomatic welding systems that are used forpersonnel carriages.


Fig. 2.16 Prototype of the magnetic levitation Transrapid manufactured with bolted aluminium large profile technology usingaluminium AlMgSi0.7 extruded sections. Source: Alusuisse

Fig. 2.15 (a) Carriage shell cross section ICE2 and (b) carriage shell cross section ICE3, self-supporting using welded large sectiontechnology. Source: ADtranz

Silo wagons of this design were designed andbuilt by Alusuisse to U.S. standards. In spite ofthe high material costs of the aluminum silowagons, their manufacturing cost per ton pay-

load is approximately 10% less than that of asteel wagon.

Road Vehicles. The development of auto-mobile manufacture including both cars and


Fig. 2.17 Tilting trailer walls of an open goods wagon finished in extruded hollow sections in the alloys AlMgSi0.5 and AlMgSi0.7.Source: Alusuisse

Fig. 2.18 Coal silo wagon produced in welded self-supporting large extrusion technology to U.S. standard. Source: Alusuisse

freight vehicles has been associated with the useof aluminum alloys from the beginning. Alu-minum gearbox and motor housings were al-ready being reported in the latter years of thenineteenth century. In 1924, the Swabische Hut-tenwerk developed a car with a self-supportingaluminum design. In 1937, BMWfitted the well-known two-seater sports car 328 with an alu-minum alloy body. In racing car manufacture,the well-known Silver Arrow manufacturerAuto Union, BMW, and Mercedes Benz usedaluminum alloys to produce the lightest chassispossible. Toward the end of 1920s, the firstbuses with aluminum bodies were built, particu-larly in Switzerland (Fig. 2.20).

After World War II, this development in-creased rapidly. The use of aluminum alloys inroad vehicles increased continuously. Today, af-ter steel, aluminum alloys are the most importantmaterial in the manufacture of automobiles. In1993, in Germany alone 315,000 metric tons ofaluminum were used in the manufacture of carsand 58,000 metric tons in freight vehicles [Gor94]. The main applications of aluminum arecastings for engine and gearbox housings, pis-tons, and cylinder heads, as well as car wheels.It is also used as a semifinished product in theform of sheets or strip for the manufacture ofbonnets and boot lids, water and oil coolers, andalso sometimes for complete sports cars bodies


Fig. 2.19 Design and construction of the coal silo wagon shown in Fig. 2.18

Fig. 2.20 Older bus body manufactured from aluminum alloys in Switzerland with a frame in extruded sections. Source: Alusuisse

as well as extruded semifinished profiles for theproduction of trim and widow frames, and forsafety components such as side-impact beams incar doors. Car superstructures and bus bodies,goods vehicle superstructures, and sidewalls, inaddition to forgings for the manufacture ofwheels and engine components, are also madefrom aluminum. This increasing use of alumi-num alloys provides these well-known advan-tages to the automobile industry:

! Lower vehicle mass and thus savings in mo-tive energy, i.e., fuel. According to [Her 90],the replacement of 200 kg of steel by 100 kgof aluminum in a car reduces the gasoline

consumption by about 0.6 to 0.8 l/km (in-creases mileage 3.5 to 4.7 mpg).

! Lower environmental pollution from exhaustgases as a result of the reduced fuel con-sumption.

! Reduction in maintenance costs due to thebetter corrosion resistance of the aluminumalloys

! Simple recycling of the aluminum alloysused as secondary aluminum

Passenger Cars. In 1958, Opel in Germanyintroduced the Rekord shown in Fig. 2.21 as anew design to the market. The car had as a newfeature for the European automobile industry


Fig. 2.21 Automobile window frame in extruded, age-hard-ened, and anodized aluminum sections on an

Opel Rekord manufactured in 1958. Source: Opel

Fig. 2.22 Rear window frame of the Mercedes W124 man-ufactured from extruded aluminum sections. The

front windshield of the vehicle had a similar frame. Source: Erbs-loh

window frames in extruded and age-hardenedaluminum alloy for the front and rear wind-screens, as well as the side windows in the doors.The aluminum frames were attached in such away to the steel sheet that the top of the doorconsisted only of the window frames with thewindow glass, as shown in Fig. 2.21. The ex-truded profiles that formed the frames were de-signed in such a way that the rubber sections thatsealed against the body could be easily locatedin the aluminum window frames. The extrudedprofiles were formed to the window frames onstretch bending machines, welded together,ground, and polished and anodized to a thick-ness of 4 to 6 lm. The section material used byOpel was initially Al99.8ZnMg and, later,Al99.8MgSi.Opel introduced this design within Germany

following pressure from the United States. Thedesign was quickly adopted by Audi, BMW, andFord. The aluminum alloy solution heat treatedduring the billet heating was extruded into water(standing wave). The sections had a weight permeter of only 0.150 to 0.850 kg. In the early

years, high demands were placed on the deco-rative appearance, in particular, on the optimumpolish. Good mechanical properties were alsorequired. The top of the door consisted only ofan aluminum frame, and this frame should notbend when the door was closed. Aluminum ex-truded profile window frames appeared in manycar models for over a decade. During this period,between 150,000 and 200,000 metric tons alu-minum sections flowed into this project. Carmanufacturers finally stopped using this deco-rative aluminum window frame construction onthe doors mainly because of the wind noise be-tween the window frame and the body associ-ated with the rapidly increasing speeds. Thecause of the wind noise was the speed-relatedsuction forces acting externally on the windowsurfaces and also the pressure forces from theoperation of internal fans on the inside of thewindow surfaces. This revealed a weakness inthe aluminum window frame design. As a con-sequence of the E-modulus of the aluminum al-loys used for the window frames being one-thirdthat of a suitable steel, the aluminum windowframes deformed elastically three times as muchas a steel frame of the same design. Profile crosssections with higher moments of inertia couldnot easily be incorporated into the door design.This did not exclude, however, the further use

of extruded profiles as frames for the front andrear car windscreens, as shown, for example, inthe E class Mercedes in Fig. 2.22. In addition,


Fig. 2.23 Hood container cover of the Mercedes 300 SL and500 SL class with extruded aluminum section

frames. Source: Erbsloh

Fig. 2.25 Side-impact beam from the Audi 8 consisting oftwo extruded sections. Alloy AlMgSil, F 31. The

side-impact beam can be seen installed in Fig. 2.27. Source: Alu-suisse

Fig. 2.24 Side door of the Audi 100 with built-in chroma-tized for corrosion protection, extruded section in

the aluminum alloy AlMgSi1, F 31 with RP0.2 " 260 N/mm2 andA5 " 10%. Source: Alusuisse

numerous extruded profiles are used in car bod-ies for a wide range of applications, includingsteering wheel adjustment, seat rails, sliding roofguides, and also for water and wind deflectorsin the roof area of the body and side windowguides. Figure 2.23 depicts the metal frame forthe folding top cover of the SL class made froman extruded profile.Aluminum extruded profiles are particularly

suited in special cases for the manufacture ofsafety components for the automobile becausethe cross-sectional shape can be exactlymatchedto the loading. They also offer favorable me-chanical properties and density and the low E-modulus as well. A typical example is the sidedoor beam that can fulfill its role in a very func-tional way. Side impact causes 30% of all roaddeaths in 25% of all car accidents in Germany.The car sides cannot be protected for space rea-sons by crumple zones as, for example, used inthe front and rear. Therefore, the car manufac-turers have over the years made great efforts toprotect the sides of cars using effective side-impact beams as well as air bags. Figures 2.24,2.25, and 2.28 show this technology in Audi ve-hicles.The impact beam must be able to absorb the

transmitted impact energy from an impact on theside door over a defined deformation displace-ment without breaking, buckling, or even dis-placement in order to protect the passengers. Re-search results have shown that extrudedaluminum alloy profiles with a symmetrical

cross-sectional geometry and sufficient proofstress and elongation are particularly suitable forthis application [Fra 89]. A correctly designedimpact beam in an extruded aluminum alloywith materials properties comparable to a geo-metrically similar steel impact beam can possessapproximately three times the elastic deforma-tion capability before plastic deformation oc-curs.Interest in the extruded age-hardened alumi-

num alloy side-impact beam combined with a


Fig. 2.26 Steering link in the alloy AlMgSi1, F 31. The con-nection on the left-hand side is from an extruded

section, whereas the round, easily deformed in the event of acrash, corrugated section with the transition to the steering col-umn was manufactured from an extruded tube. The corrugatedregion is heat treated to a strength of F 22 to F 25. Source: Alu-suisse

side air bag is increasing because the goodphysical and mechanical properties, in particu-lar, the elastic behavior, enable the safety re-quirements to be fulfilled. Many automobilemanufacturers are now installing them.Naturally, there are numerous safety compo-

nents that are manufactured from extruded alu-minum profiles. Figure 2.26 shows a steeringlinkage in which the left-hand link consists ofsections of extruded profiles, whereas the flexi-ble right-hand part is manufactured from impactextruded tube sections with formed bellows. Inan accident, the bellows deform so that the im-pact on the steering column is reduced. Thegood experience obtained with the deformationbehavior of side-impact beams made from ex-truded age-hardened aluminum hollow sectionshas now been used in automobile plastic bumperbeams with integrated aluminum hollow sec-tions in the alloy AlMgSi0.5 or AlMgSi0.7.These sections naturally have to match the pro-file of the bumper beam, i.e., they have to bebent. Whereas this bending operation is carriedout today on a large scale on stretched extrudedprofiles with significant cost for the bending, de-pending on the section geometry, possibly fol-lowed by a sizing operation, these deformationprocesses can be carried out in the United Statesduring the extrusion process. The low hot flowstress of the aluminum alloy aids the bendingprocess.The introduction of defined and legally re-

quired targets of weight saving, energy saving,and simple recycling of the materials used hasinitiated significant innovations in recent yearsin the automobile industry. Previously, alumi-num alloys were generally used for simple parts.

However, in cars this did lead to weight reduc-tions of about 60 kg in Europe and about 80 kgin the United States. The desire for larger weightsavings now has resulted in greater use of lightmaterials. In the future, engine and gearboxhousings will be made primarily from aluminumalloys. Car manufacturers are also replacingload-carrying steel automobile components withaluminum. This gives an additional weight sav-ings of 60 to 70 kg and a definite improvementin the ride because of the significantly lower un-damped weights.Meanwhile, the automobile driver has be-

come increasingly more demanding. The stabil-ity of the body, the airbag, and the side-impactbeams, ABS and effective crumple zones pro-vide passenger protection. In addition, air con-ditioning, CD systems, navigation systems, andother luxurious fittings should make traveling ina car as pleasant as possible. Simultaneously, thefuel consumption should decrease and the ma-terials from old vehicles be easily recycled.In the future, these conflicting demands will

be met by the use of light body designs in steel,aluminum alloys, improved magnesium alloys,and to a limited extent by fiber-reinforced plas-tic, if necessary, up to self-supporting structures.As early as 1950, Pakiney built the DYNAPANHARD car with extensive use of AlMg3sheet and, later, AlMgCu. The car weighed only650 kg and was extremely economical. In 1990,Honda developed the sports car NSX withAlMgSi1 sheet, and Rover has used for manyyears in the Land Rover aluminum sheets for thebody; initially, AlMgCu and, today, AlMgSi1[Alp 94]. The decisive step was made by AUDIAG with the production of the AUDI A8 shownin Fig 2.27. The body is made entirely of alu-minum.This breakthrough of aluminum into the steel

domain has both shocked and challenged thewide strip manufacturers (body sheet). They aretrying to counter this development with intelli-gent solutions for complete steel chassis, for ex-ample, with the use of prefinished body parts,tailored blanks. Tailored blanks are cut to size,designed for the load, body panels laser weldedtogether from steel sheets of different thickness,strength, and surface quality. These prefinishedbody parts, for example, complete wheel hous-ings, enable assembly costs and also weight tobe reduced. This is the start of a process thatshould finish with the ultralight steel car body.However, the high point of this development to-


Fig. 2.28 Space frame of the Audi A8 shown in Fig. 2.27

Fig. 2.27 Audi A8 Quatro with a body of age-hardened aluminum alloys using the Alcoa space frame concept. Source: Audi

day is the Audi A8 and the Audi A2 with thespace frame construction of Alcoa. This con-struction principle can be seen in Fig. 2.27 to2.29. Audi uses for the production of the alu-minum body aluminum alloys containing thesame alloying elements, a basic requirement forease of recycling. The extruded sections neededto assemble the space frame are produced in

the age-hardening alloys AlMgSi0.5 andAlMgSi0.7. Supporting floor panels consist ofthe age-hardening alloy AlMgSi1Cu, smallsheet parts from the non-heat-treatable alloyAlMg5Mn. The die cast nodes necessary forjoining the preformed and age-hardened ex-truded profiles to balance out the tolerances forthe space frame of the Audi A8 were manufac-


Fig. 2.29 Space frame of the Audi A2 in extruded sections, sheet and castings. Source: Audi

Table 2.1 Aluminum alloys used for the aluminum body of the Audi A8Material AA(a) Temper Rp0.2 (N/mm2)(b) Rm N/mm2(c) A5 %(d)

Sheet AlMg0.4Si1.2 6016 T6 200 250 14AlMgSi1Cu 6009 T6 230 280 10AlMg5Mn 5182 . . . 135 270 25

Vacuum die casting AlSi10Mg . . . T6 120–150 180 15Permanent mold casting AlSi7 . . . T6 200 230–250 15Extruded section AlMgSi0.5/0.7 . . . T6 210–245 1.08 Rp0.2 11

(a) Aluminum Association designation. (b) Rp0.2 is 0.2% proof stress. (c) Rm is tensile strength. (d) A5 is elongation after fracture. Source: Audi

tured with the vacuum casting process in theheat-treatable alloy AlSi10Mg. Other cast com-ponents consisted of AlSi7. Die cast componentsfor tolerance compensation were not used for thespace frame of the A2.Finally, cold-worked strip sections in the flow

line free (Luders lines) and heat-treatable alu-minum alloy AlMg0.4Si1.2 were used as exte-rior body panels. Table 2.1 provides an overviewof the materials used to build the aluminum bodyof the Audi A8.The automobile manufacturer joins the deliv-

ered prefinished and age-hardened profile sec-tions to assemblies by MIG welding with the aidof jigs. The complete space frame is then builtusing the same joining technique. The floor pan-els and, in particular, the 1.0 to 1.15 mm thicksheets for the body exterior skin were fixed us-ing other joining techniques including, amongothers, self-piercing rivets. Finally, the finishedbody in white is age-hardened at a temperatureof 230 !C for 30 min. It is mainly the body pan-

els that harden during this heat treatment. Thesections of the space frame heat more slowlybecause these are shielded by the body outerskin during the heat treatment. For this reason,the bent profile sections for the space frame haveto be supplied age-hardened in such a way thatthey harden only slightly during the age-hard-ening process described and do not over age. Inparticular, the softened peripheral zones of thesection welded from the MIG welding should asfar as possible reharden. The complete alumi-num body of the Audi A8 is approximately 200kg lighter than a conventional steel body of thesame size.Bus Manufacture. The manufacture of buses

from aluminum alloys has a tradition in Swit-zerland, as shown in Fig. 2.20. The Alpine coun-try started to consider the reduction in weight ofgoods vehicles in the 1920s. The engine powersavailable at this time were still very limited andcould therefore be better utilized with a lowerweight. The Swiss with their mountainous re-


Fig. 2.30 Old lattice design for coach construction as shownin Fig. 2.20 manufactured from extruded alumi-

num sections. Source: Alusuisse

Fig. 2.31 The study of a coach presented at IAA 1987 with bolted, supporting lattice frame construction in extruded aluminumsections. Source: Alusuisse

gions never lost sight of this basic principle; itincreased in importance after World War II.Other countries, including Germany, also be-came interested in these solutions.Extruded profiles in aluminum alloys were the

natural solution for the economical lightweightconstruction of buses. Their low density andgood mechanical properties, as well as the op-timum shape-forming capability combined withthe use of modern joining techniques, providednot only the prerequisite for economic designsof bus superstructures but also for a rationaltransport of the passengers.The bus construction concept is based in prin-

ciple on a lattice frame design of extruded alu-minum sections similar to the space frame of theAudi A8 (Fig. 2.28). These profiles are weldedtogether as shown in Fig. 2.30. The body panelsare attached with suitable joining techniques.Buses built entirely of aluminum according to

this system are in operation today in Switzer-land, Denmark, and Norway. System-built bussuperstructures are also common in the UnitedStates with sidewalls in extruded sections simi-lar to those used today in Europe for railwayrolling stock [Alp 94].More than a decade ago, Alusuisse developed

a bolted bus superstructure with good results.The nucleus of this aluminum bus superstructureis the bolted corner elements as shown in Fig.2.32, which, combined with the system sections,provide for simple assembly. After successfultrials in their own country, other European coun-tries became interested in the process. The twocompanies Schweizerische Aluminium AG andthe German company Kassbohrer presented tothe International Automobile Association (IAA)in 1987 a study commissioned by the Ministryfor Research and Technology of a bus manufac-tured of aluminum using the bolted design underthe name SETRA CONCEPT BUS. This bus isshown in Fig. 2.31 and the design of the boltedcorner joints of the Alusuisse system M5438 inFig. 2.32.The bolted design of the supporting aluminum

lattice frame had considerable advantages overa similar welded design. The bus superstructurecan be produced extremely economically andquickly without labor-intensive reworking as aresult of welding distortion. There is also theadvantage for the vehicle owner that accidentrepairs can be carried out in a relatively shorttime and to a relatively high quality. This assem-bly system has been successful in many coun-tries. Moreover, the Swiss have also used thismethod of assembly for light rolling stock forpassenger traffic. The carriage bodies of the ex-perimental vehicles of the magnetic levitatedTransrapid described in the section “RollingStock” and Fig. 2.16 are built from bolted ex-truded aluminum sections.


Fig. 2.32 Bolted Alusuisse system M5438. Source: Alusuisse

Fig. 2.33 Typical aluminum hollow sections for goods vehicle sides in the alloy AlMgSi0.5. Source: Alp 94

Road Freight Vehicles. For a long time, trans-port companies in Europe have been subjectedto increasing ruinous competitive pressure withincreasing costs. Consequently, there is ongoinggreat interest in freight vehicles with lowweights, but with optimum load capacity andlow maintenance costs. This leads to a reductionof the transport costs and an increase in the com-petitiveness.

The increase in the transport capacity can beachieved in two ways:! By increasing the size of the freight vehicles,which has also been carried out in the past.Today, freight vehicle sizes have reachedtheir limit because of the permitted roadloads.

! By reducing the vehicle weight using spe-cific lightweight construction without anyfurther increase in the road loading. This ap-proach offers potential for the future.Specific aluminum alloys and, in the future,

also magnesium alloys, are available for the de-velopment of lightweight commercial vehicles.These alloys are characterized by the low den-sities, adequate material properties, corrosion,and weather resistance with low maintenancecosts as well as optimum design capabilities. Asin many such applications, extruded semifin-ished products are particularly suitable, particu-larly sections with their unlimited cross-sec-tional shapes. The relatively simple recycling ofthese materials as secondary materials also playsa role.Systems for the assembly of truck planking,

in particular, truck sides, had already been de-veloped in the first half of the 1960s by the alu-minum industry in conjunction with the manu-facturers of freight vehicle superstructures. Thesidewalls manufactured from extruded hollowsections shown in Fig. 2.33 have proved to bemore stable and require less maintenance thanthe old wooden sidewalls and also are decora-tive. It is possible today to produce on largepresses small truck sides in one piece as shownby the profiles in Fig. 2.34. Trucks with the oldwooden superstructures disappeared within afew years with aluminum profiles replacingwood for many loading space floors.


Fig. 2.35 (a) Tipping wagon with welded tilting body in aluminum sheet reinforced with round spars of extruded aluminumsections.Source: Alusuisse. (b) Tilting body from (a) constructed from: 1 and 2, sheets of AlMg4.5Mn; 3, extruded aluminumcurved

section in AlMg4.5Mn; 4, round spar with AlMgSil extruded aluminum sections and a cross-sectional geometry of 4.1: 5, top edge inextruded aluminum section

Fig. 2.34 Five-core hollow section for goods vehicles sides with a width of 530 mm and a height of 25 mm and a six-core sidesection 800 mm wide and a height of 25 mm manufactured in AlMgSi0.5, F 25. Source: Alusuisse

The use of aluminum alloys for truck andtrailer constructions for the transport of bulkgoods and liquids has proved to be particularlyeconomic, for example the silo rolling stock inFig. 2.18. This also applies to coarse bulk goodstransported with road vehicles. Silo trailers arefrequently manufactured entirely from alumi-num alloys. The chassis of the trailer is fre-quently manufactured from extruded aluminumsections. In Europe, silo and liquid transporterspredominantly use this type of aluminum super-structure [Koe 88]. Figure 2.35 also shows aloose-goods vehicle for building sites, with a tip-ping aluminum body made in AlMg4.5Mnsheets with transverse reinforcement (roundspars) of extruded AlMgSi1 sections. Finally,Fig. 2.36 shows a trailer with a covered tippingbody made entirely of aluminum sections. Allaluminum tipping body shells have low wear.

Planked superstructures in extruded alumi-num sections have also proved successful asshown in Fig. 2.37. In spite of the higher ma-terial costs for aluminum alloy designs, these areviable because of the increase in load capacityderived from the weight saving. In contrast toother European countries, in Switzerland, theplanked trailers are made completely from alu-minum, including the load-carrying parts of thechassis. In the United States, the use of alumi-num alloys for goods vehicles raises fewer ques-tions than in Europe.The use of aluminum components made from

extruded semifinished hollows for superstruc-tures as well as chassis, but also from strip andsheet for the manufacture of containers andwheel rims and so forth, will increase in the fu-ture for goods vehicles. The aim is an optimumlow vehicle weight with optimum carrying ca-


Fig. 2.37 Trailer with planked construction and chassis in extruded aluminum sections. Source: Alusuisse

Fig. 2.36 Tipping trailer with covered body made entirely from extruded multicore hollow sections for the transport of fine pow-dered goods. Source: Alusuisse

pacity. Aluminum is well suited for this. Finally,the recycling of the used aluminum from old,no longer usable goods vehicles is relativelysimple.

Aircraft manufacture is one of the oldest ap-plications of aluminum. As early as 1897, alu-minum-base materials were used for the con-struction of airships, and age-hardeningaluminum alloys enabled the German aircraftmanufacturer Junkers to introduce the completemetal airplane (Ju-4) in 1917. Whereas today,certain components of modern aircraft such aselevators, rudders, and landing flaps are madefrom specific weight saving and carbon fiber-reinforced plastics (CFP), aluminumwill remain

in the future the dominating metallic-base ma-terial for the manufacture of aircraft in the formof plate, sheet, extruded sections, and cast com-ponents. Aluminum alloys still have potentialfor further development. The aircraft outer skinwill still be made from aluminum alloys. Im-portant parts of the wings, stiffeners in the shapeof spars and stringers are also made from high-strength aluminum alloys as well as windowframes, connection nodes, and landing gearcomponents, including the forged aluminumwheel rims. However, in spite of their being thedominant materials used, the trend is for the useof aluminum alloys in the entire Airbus fleet toreduce, as shown in Fig. 2.38. Carbon fiber-


Fig. 2.39 Airbus fuselage cell with roll clad AA2024 sheet skin longitudinally reinforced with extruded stringer sections in AA2024and with transverse reinforcement of spars in roll clad AA2024 sheet. The clearly visible cabin floor supports are man-

ufactured from AA7075 extruded sections. Source: VAW

Fig. 2.38 The percentage of metallic materials in the Airbus fleet. Source: Daimler Benz Aerospace Airbus

reinforced plastic materials do have a lower den-sity and much higher mechanical properties, butthey also have a high impact crack sensitivitywith low ductility and toughness. Moreover,their manufacture involves complex productionand quality control processes. They are thereforecorrespondingly expensive [AlH 71, Alt 88, Alp94].Extruded sections are used in aircraft in dif-

ferent places for load-carrying or reinforcementfunctions. For example, they are used as longi-tudinal stiffeners for the sheet skin of the aircraft

fuselage in the form of stringers. Figure 2.39shows stringer profiles as longitudinal stiffeningof an airbus fuselage where the external skin isproduced from roll clad aluminum sheets in thealloy 2024. Extruded sections are used for theseat rails and the floor transverse supports. Thelatter can also be easily seen in Fig. 2.39. Thecross-sectional geometry and the relative size ofthe extruded profiles used are shown in Fig.2.40. Spars for transverse stiffening of the fu-selage skin as shown in Fig. 2.39 are made fromAA2024 strip.


Fig. 2.41 Distribution of the semifinished products used in (a) the Airbus fleet compared with (b) the Boeing fleet. Source: DaimlerBenz Aerospace Airbus

Fig. 2.40 Extruded sections for the Airbus aircraft in aluminum alloys AA2024 and 7075. Source: Daimler Benz Aerospace Airbus

The fraction of extruded profiles within thetotal of semifinished products used for aircraftin the Airbus fleet is around 11%; in contrast toBoeing aircraft, where it is 41%. As Fig. 2.41shows, with Boeing, the fraction of extrudedaluminum profiles used dominates when com-pared with other semifinished products. With theAirbus fleet, sheet forms the largest fraction.Weight reduction also plays an important role

in modern aircraft manufacture. The demand isfor low-density materials with good mechanicalproperties that can be stressed optimally to theoperating safety limit. Since Wilm’s chance dis-covery in 1909 at the Durener Metallwerke ofthe age-hardening capability of AlCuMg, the

aluminum industry has focused on the aim ofproducing high-strength alloys that can be hotand cold worked. The alloy groups AlCuMg andAlZnMgCu, as well as the new somewhat dif-ficult AlLi alloys, offer the aircraft industry alu-minum alloys that can be statically and dynam-ically loaded to high stresses and processed tosemifinished products by rolling, forging, andextrusion. Aluminum alloys with high hotstrengths are also available for supersonic air-craft [Alp 94].The classic aluminum alloys for aircraft con-

struction have been modified over the years andtheir heat treatment so specialized that today,they not only achieve optimum materials prop-


Fig. 2.42 Extruded tube with integral stringers in the alu-minum alloy AA6013. Source: Daimler Benz

Aerospace Airbus

Fig. 2.43 Extruded tube from Fig. 2.42 opened out for thefuselage skin. Source: Daimler Benz Aerospace

Airbus

erties, but also largely meet the corrosion re-quirements of the aerospace industry. In con-trast, the aluminum alloy AA8090 has beenrecently developed specifically for aircraft con-struction. Compared with other high-strengthaluminum alloys, it has a density 10% lowerwith good static and dynamic properties and anE-modulus that is approximately 10% higher[Ren 97]. Because of the extreme material load-ing in aircraft, the aerospace industry naturallystill demands the further development of exist-ing aluminum alloys and the development ofnew aluminum alloys with even higher mechan-ical properties. Further developments for theAirbus fleet concentrate at the moment on thehigher-strength alloys in the AlZnMgCu alloyfamily with better corrosion resistance and thenew development of particle reinforced alumi-num alloys. An AlMgSiCu alloy Aluminum As-sociation 6113 (AA6113) reinforced with25% volume SiC particles has an E-modulusdouble that of nonreinforced alloy variants [Ren97].The development of high-strength aluminum

alloys for aircraft construction and the require-ment for ever larger and more expensive sec-tions has naturally had an effect on extrusionplants. The high-strength aluminum-base alloysare all difficult to extrude. To meet the materialsproperties required by the aerospace industry,they have to be handled carefully after extrusion.Not only are optimum material properties forstatic as well as dynamic loading required foraircraft alloys, but also the residual stresses ofthe first type have to be as low as possible forstress and machining purposes.There is not only ongoing further develop-

ment in aerospace materials, but also, naturally,in aircraft construction itself. New fuselage con-structions with integrated stringer sections arebeing developed for the Airbus fleet. These en-able the aircraft fuselage sections to be manu-factured with 10% less weight and are up to 25%less expensive than the conventional rivetedmethod of construction. Two concepts are fa-vored:

! External skin in sheet, which is welded to-gether to form the fuselage and then bondedwith extruded aluminum stringer sections bylaser welding

! Extruded external skin with 1.6 to 4 mmwallthickness and integrated stringer sections asshown in Fig. 2.42 to 2.44, e.g., in principlean aircraft fuselage using the welded alumi-

num large section technology used in themanufacture of ICE wagons.

Both concepts are associated with the replace-ment of the roll clad sheet material 2024 by thenew weldable materials AA6013 and AA6056based on the AlMgSiCu family.The second concept leads to a new perspec-

tive in the use of very wide extruded profiles for


Fig. 2.44 Extruded cross-sectional geometry of the extrudedexternal skin with integrated stringers. Source:

Daimler Benz Aerospace Airbus

the fuselage external skin, a special demand onaluminum extrusion plants with large extrusionpresses. Whereas the fuselage construction to-day involves sheets 2500 mm wide, even thelargest extrusion press in the industrializedcountries cannot, at the moment, produce equiv-alent sections with a flat cross-sectional geom-etry. Therefore, the production of extruded sec-tion tubes with integrated stringers as shown inFig. 2.42 has been considered among otherideas. They can be opened out into a wide profileas shown in Fig. 2.43. Using this productionmethod, which is not unusual for extrusion, ex-ternal skins up to 2100 mm wide can be pro-duced. However, the required wall thickness of1.4 to 4 mm presents process-related extrusionproblems. It is not possible to avoid a certainvariation in wall thickness in the extruded tubebecause of the tendency of the mandrel to ec-centricity, i.e., movement from the press axis.Therefore, extremely serious considerations be-ing given within extrusion plants for the solutionto this problem, assuming a solution is indeedpossible.

Watercraft. A low weight also brings signifi-cant advantages to ships. As with other methodsof transport, low weights can be achieved by theuse of low-density construction materials. Suit-able aluminum alloys are also available for wa-tercraft. Lightweight construction methods pro-vide the following advantages to watercraft:! The carrying capacity of the watercraft is in-creased: its radius of action can thus be in-creased.

! The stability of the ship is improved by light-weight superstructures lowering the center ofgravity.

! The draft of the ship can be reduced.! Painting and other surface protection mea-sures can be spared by the use of seawater-insensitive materials including AlMg3,AlMg5, and AlMg4.5Mn for ship compo-nents that come into contact with seawater.This reduces maintenance costs.

! The antimagnetic properties of the aluminumalloys simplify navigation.In spite of this, the complete aluminum ship

has not prevailed. Some examples were built inthe decades after World War II, for example, theBinnentanker motorboat Alumina in the 1960sin Germany with a draft of 1000 metric tons, aswell as in 1967, in the United States, the sea shipSacal Borincano. Its construction required ap-proximately 345 metric ton of sheet and ex-truded sections in the alloy AlMg4.5Mn. The119 m long completely aluminum ship with awelded design was used to transport semitrailersbetween Miami and Puerto Rico.Today, the production of entirely aluminum

ships is limited to small ferries and passengerships for coastal and inshore operation as wellas special ships such as rescue boats and hov-ercraft. Private yachts, in particular, are madeentirely of aluminum. The usual method of con-struction preferred for these ships is a combi-nation of spars in extruded AlMgSi1 sectionsand an outer skin of AlMg or AlMgMn weldedsheet. The extruded profiles used are, therefore,the load-carrying structural components.The superstructure of large ships with steel

hulls is completely different. The superstructureis preferably made using aluminum lightweightconstruction techniques for stability reasons.The lightweight construction technique enablesthe center of gravity of the ship to be loweredor the height of the superstructure increasedwithout impairing the stability of the ship witha higher center of gravity. The design of the su-perstructure in the lightweight constructionmethod has to take into account the different E-modulus of iron and aluminum alloys to copewith the temperature-dependent stresses that oc-cur between the two materials, as well as preventcontact corrosion at steel/aluminum joints by theuse of insulating elements [Alh 71, Alt 88, Alp94].Large ships need considerable quantities of

aluminum semifinished products in the form ofsheet and profiles for aluminum superstructures(Fig. 2.45). The superstructures of the passengerships United States, Norway, and the QueenElizabeth II each required approximately 2000


Fig. 2.46 Multicore hollow section for mobile intermediate ship decks for sheep transport. Source: Alusuisse

Fig. 2.45 Aluminum superstructure of a passenger ship. Source: Alusuisse

metric tons of aluminum. Modern large aircraftcarriers require similar large quantities of alu-minum semifinished products for their super-structures. Finally, large section technology hasalso been used for lightweight construction tech-niques in ship superstructures. The use of largeprofiles reduces the assembly costs.Extruded large multicavity sections are used,

for example, in ships in the fishing industry asrack floors with through flowing coolant for thestorage of fish in the cold rooms. Mobile inter-mediate decks for ships for the transport of ani-mals can be produced from large aluminum pro-files for economic reasons, as shown in Fig.2.46. The alloys AlMgSi0.5, AlMgSi0.7, andAlMgSi1 are used for these and for the sup-

porting structures within the superstructures ofthe ships.

2.2.2.2 Machine Manufacture, ElectricalMachines, and ElectricalEquipment

The manufacture of machinery and electricalmachines was, for a long time, dominated byiron-base materials, but with time this haschanged. Other materials with their favorableproperties are threatening the domination of theiron-base alloys. During the past 20 years, per-sonnel costs have increased more rapidly thanthe material costs. Aluminum-base materialswith their very specific materials properties have


Fig. 2.47 AlMgSi0.5 extruded section for electric motor housings (a) and a large section for the console of a high-speed printer(b). Source: Alusuisse

today secured a respectable position in this field[Cor 95].For a long time, the use of aluminum alloys

in machine manufacture was restricted to thesmaller components that could be produced bycasting, forging, stamping, or even extrusion.The future emphasis for manufacture with alu-minum alloys will be on the large section tech-nology. This gives the designer a new designelement to be used to achieve optimum technicaland economical solutions [Alp 94]. The load andfunctional related shape capabilities of these ex-truded profiles as well as the high dimensionalaccuracy have revolutionized many designs, asshown in the examples depicted in this section.Low density and good mechanical properties

make aluminum alloys interesting for movingmachine components with high accelerationsand decelerations. Nonmagnetic properties, aswell as good thermal conductivity, ensure thataluminum alloys play an important role in themanufacture of electrical machines and electri-cal equipment. Electric motor housings belongto the most important aluminum products in theelectrical industry, as shown in Fig. 2.47(a).Weight advantages, free choice of shape, and thegood thermal conductivity of low-alloyed alu-minum materials have resulted in aluminum re-placing cast iron and steel for electric motorhousings [Joh 85, Tas 93]. Extruded aluminum

sections provide for electric motor housingsalong with the functional related cross sectionalgeometry:! A large heat-conducting housing surfacewith extruded cooling fins with significantlynarrower spacings and thinner wall thicknessthan cast housings

! Integrated cooling channels depending on re-quirements as shown in Fig. 2.47

! An extruded material with high strength andgood elongation significantly supersedingthe mechanical properties of the earlier casthousings

! Housing material not susceptible to corro-sionElectric motor housings with extruded feet,

cooling fins, and cooling channels can literallybe obtained as finished components by cross cut-ting the extrusion. Even with small or moderateproduction runs, the manufacturing costs of theextruded motor housings are well below thoseof cast aluminum housings. Bus bars (Fig. 2.48)from aluminum sections with pressure clad and,more recently, mechanically bonded layers offerritic steel are produced to supply S and Utrains.The options of large section technology in-

clude the assembly simplifying large sectionshowed in Fig. 2.49 for the tool carrier of a ma-


Fig. 2.48 Bus bar sections in aluminum alloys with pressureclad layer of stainless steel. The bus bars from S

and U trains collect the electrical energy through the stainlesssteel layer. Source: Alusuisse

Fig. 2.49 Installation-friendly large section in the alloyAlMgSi0.5 for the tool holder of a machining cen-

ter. Source: Alusuisse

Fig. 2.50 AlMgSi0.5 support and housing sections for the scanner of a carpet tufting machine. Source: Alusuisse

chining center as well as the carrier and housingsection for the scanner of a carpet tufting ma-chine in Fig. 2.50. Frequently, the aluminumprofile leaves the extrusion plant as a ready-to-install machine component, i.e., application andfunction specific extrusion, age-hardened, andcut to length. In this sense, the aluminum largesection can practically be conceived as a finishedsystem component for simple installation. Thecross-sectional geometry of the extruded sectioncan be almost ideally matched to the functionand loading, and the lattice geometry of the ex-trusion profile makes the large section very sta-ble and stiff. Aluminum large sections for ma-

chines, fixtures, and transport systems cantherefore make a significant, and perhaps eventhe most important, contribution to the entire de-sign. Last but not least are the significant eco-nomic advantages that make aluminum sectionseminently suitable for the manufacture of ma-chines and electrical machines as well as for themanufacture of numerous traditional products.Large section technology and integral design re-duce the assembly costs. They replace completesteel designs with one section and thus eliminatemany manufacturing steps.Using a hot circular saw and a food slicing

machine for sausage and cheese as examples,


Fig. 2.51 Application of large sections in the alloy AlMgSi0.5 for (a) the table of a wood circular saw and for (b) the table of a foodslicer. Source: Alusuisse

Fig. 2.52 Cross section of an 800 mm wide large section inthe alloy AlMgSi0.5 for the production of fixing

plates for pneumatic control elements. Source: Alusuisse

Fig. 2.53 Aluminum section in the alloy AlMgSi0.5 for themanufacture of electropneumatic control units.

Source: Alusuisse

Fig. 2.51 illustrates the ideal way an extrudedsection can be matched to the function of a ma-chine and its operation [Als Pr].The large section shown in Fig. 2.52 for the

manufacture of fixing plates for pneumatic con-trol elements shows an example of these capa-bilities. Figure 2.53 demonstrates the cost sav-ing, production technological possibilities aswell as the process technical advantages of func-

tion matched aluminum extruded sections de-signed as a section for the manufacture of elec-trical pneumatic control units. Rotor blades ofwind electrical generators are usually made frommulticavity hollow sections. Extruded alumi-num sections dominate as the supporting ele-ments in transport systems such as modulartransfer systems, linear vibration conveyors, and


Fig. 2.54 Extruded blanks in AlMgSi0.5 for rotors of the aircompressor of a pneumatic tanker pumping unit

for sewage. Source: Honsel

Fig. 2.55 Example of a heat sink in the alloy AlMgSi0.5 forthe cooling of the thyristors of a compact disc

player

so forth. It is not only aluminum large sectionsthat have proved to be advantageous for ma-chine design, small sections can also offer sig-nificant advantages, for example, the extrudedblanks for the rotor of an air compressor. Theslots to receive the vanes are extruded in thesection. Figure 2.54 shows this quite clearly. Theslots have to be milled out of the blanks in steelrotors.Pure aluminum and low-alloyed aluminum al-

loys including AlMgSi0.5 are good conductorsof heat. Extruded tubes and sections in thesema-terials are therefore used for heat exchangers andcooling elements. Nests of tubes made from ex-truded pure aluminum are required in largequantities in the chemical, petrochemical, andfood industries. In air conditioners, small, flatmulticore hollow sections are used. Tube sec-tions are used in recuperative and regenerativesystems, including heat exchangers and also so-lar panels. The use of hollow sections in con-densers for liquid nitrogen tanks is well known.The high-power electronic industry requireshigh-power cooling bodies as shown installed inFig. 2.55. Using separately extruded base andfinned sections joined together by a rolling pro-cess in which the finned sections are firmlyrolled with their feet in the slot of the base sec-tion, high-power cooling elements are manufac-tured as shown in Fig. 2.56 [Tas 93].

Naturally, this description of the applicationpossibilities of extruded aluminum sections inthe manufacture of machinery, electrical ma-chines, and electrical equipment can only justtouch on the full range and the versatility. Theready-to-install integral component made froman extruded section has become an importantfactor in the industries mentioned thanks to largesection technology. This gives the designer theability to develop machine specific solid andhollow sections the practical nature of which re-duces the cost of the product.

2.2.2.3 ArchitectureBuildings. The destruction of the West Eu-

ropean cities initiated a building boom in the 50years after World War II. Large quantities ofbuilding elements including windows and doorswere needed. Many new commercial buildingsas well as offices were fitted with aluminumcladding, which had been seen in the UnitedStates.This accelerated the penetration of aluminum

into building. In addition, architects appreciatedthe silver metal.Since then, large quantities of aluminum

semifinished products are consumed by thebuilding sector. Today, aluminum is one of themost important materials in buildings. Over theyears the metal has gained a specific marketwith its decorative surface finish and its goodcorrosion properties. Today, the building sector


Fig. 2.56 Various high-efficiency heat sinks constructed from extruded AlMgSi0.5 elements to remove the heat produced fromelectronic systems. Source: Alusuisse

Fig. 2.57 Skyscraper of the Dresdner Bank in Frankfurt, Ger-many, with a naturally anodized aluminum facade

alone accounts for 15% of the total aluminumconsumption of Germany and is therefore thesecond largest consumer of this material afterthe transport sector [Alz 97]. The main appli-cations are the door and window sectors aswell as building facades, followed by roofs,internal walls, conservatories, and building en-trances.Aluminum facades are usually used for im-

posing buildings, for example, large retail stores,company head offices, and large bank buildingsand official buildings. Over time, specific flexi-ble building systems have been developed thatcan be easily installed. The base structure of ex-truded sections provides the support for the fa-cade and is usually invisible after installation.Aluminum-base structures can also be used forbuilding facades in other materials.The high strength of the aluminum alloys

used in building applications enables ambitiousfiligree but reliable designs to be produced.However, when this material is used with othermaterials, such as steel, the different physicalproperties of the materials have to be taken intoaccount. In particular, the significantly lower E-modulus and the higher linear coefficient of ther-mal expansion of aluminum have to be allowedfor. Also, the lower solidus temperature of thealuminum alloys used in high-rise buildings

compared with steel has to be considered inthe context of fire prevention measures. TheAlMgSi-base metallic construction materialshave a solidus temperature of only about 580 !C.


Fig. 2.58 Aluminum glass facade of a commercial building.Source: Hueck

Fig. 2.59 Aluminum facade of the post office in Odense,Denmark, with the supporting vertical facade sec-

tion. Source: Alusuisse

Fig. 2.60 Aluminum glass facade in combination with anilluminated courtyard and curved roof over the en-

trance of the Euro-Cetus-Complex in Amsterdam, Netherlands.Source: Hueck

Over time, different types of building facadeshave been developed in addition to the entirealuminum facades shown in Fig. 2.57. Alumi-num glass facades as shown in Fig. 2.58 are be-coming more popular. They provide a lot oflight; are easy to maintain; and energy producingelements such as photovoltaic modules [Alp 94],which fulfill specific heating requirements, canbe included. Building facades of mixed designs,for example, stone and aluminum as well asstone and aluminum-glass, are found to an in-creasing extent, as shown in Fig. 2.58 and 2.59.Finally, pure stone facades with stove enameledaluminumwindows and frames make a good im-pression as can be seen in Fig. 2.63.Frequently, in imposing buildings glass

roofed courts with curved glass roof construc-tions are integrated into the building as shownin Fig. 2.60. These are usually associated withthe entrances to the building. These can also befound in smaller buildings. Today, curved glassroof designs can be produced easily from bentextruded sections as shown in Fig. 2.61. Ther-mally insulated aluminum sections are used aswith windows and doors.The different systems for building facades in-

clude the fixing to the building wall. Frequently,a steel skeleton is fixed to the wall onto which


Fig. 2.61 Curved glass roof with aluminum sections for anilluminated courtyard of a sports center in France.

Source: Cintro Systems

the curtain wall is then fitted. Figure 2.62 clearlyshows this in the aluminum glass facade wall de-sign from Erbsloh-Aluminum for the entrance ofthe Neuss fire station in Hammerdamfeld.The largest amount of aluminum used in

buildings is for windows and doors. They arethe central part of building architecture. The useof suitable aluminum alloys such as AlMgSi0.5and sometimes AlMgSi0.7 ensures that thebuilding components are low maintenance com-pared with other window materials, with the ex-ception of plastic-based materials. The hot-working process extrusion enables visually veryambitious and decorative window designs to bedeveloped, a possibility that is hardly possiblewith, for example, wood. This, combined withthe surface treatment of the aluminum buildingcomponents, can have a strong influence on theappearance of a building’s facade as (Fig. 2.63).Windows and doors have a major influence

on the office and domestic quality as well as theenergy efficiency of the building. Before the en-ergy crisis in the 1970s, aluminum windows anddoor frames and sashes were installed withoutthermal insulation. Earlier designs did not even

include double glazing. This had the disadvan-tage of cold bridges forming because of the goodthermal conductivity of the aluminum alloysused. At low external temperatures, the alumi-num material transported the cold to the insideof the window and the moisture condensed fromthe room air onto the section surface and couldeven freeze in winter. An ice film formed. In thesun’s rays, the reverse happened, even with lowexternal temperatures. The metallic windowframes heated up and transferred their heat tothe room air. The metallic window frames actedas radiators.This changed during the energy crisis toward

the middle of the 1970s. Whereas previously,windows and doors were usually consideredfrom the architectural viewpoint, the require-ment for thermal insulation and sound insulationrapidly grew. The window and door sectionswere insulated using inherently stable plasticbridges with low thermal conductivity as shownin the sash section in Fig. 2.64. This process wasalso introduced for the manufacture of alumi-num facades. Figure 2.64 also shows the use ofthe extruded aluminum spacers for doubleglazed windows in Fig. 2.65.A special aluminum window design, the

wood aluminum window, was developed at arelatively early stage even before the energy cri-sis of the 1970s. This design arose from the con-cept of having the well-proven and warm woodwindow frame on the inside, while outside, thealuminum section used made the windowweather tight with all the advantages of the cor-rosion-resistant aluminum alloy with a surfacetreatment such as anodizing, wet painting, orpowder coating for additional protection. This isshown in Fig. 2.66.Conservatories built onto domestic houses as

shown in Fig. 2.67 have been popular for manyyears. These extensions can increase the livingarea, as well as improve the climate of the livingarea by light, plants, and solar energy.Aluminum extrusions are naturally best suited

for the design of these conservatories. Theirgood strength with low weight and the produc-tion of application suited section geometry en-ables architecturally attractive buildings to beproduced. In special cases, very light houseswith conservatory-based design have been builtusing extruded aluminum sections (Fig. 2.68).Movable interlocking walls also benefit from

the low weight of the aluminum alloys used andfrom the solid appearance of the sections. Withthe good formability of the alloys used, curved


Fig. 2.62 Ekonal-FV70 aluminum glass facade system from Erbsloh-Aluminium for the Neuss fire station in Hammerdamfeld. Thesteel framework for fixing the facade is shown by the double T beam on the right-hand side of the drawing. Source:

Erbsloh-Aluminium

Fig. 2.63 Refurbishment of the NCR at Spree-Ufer in Berlin, Germany, with the blue baked painted aluminum window frames


Fig. 2.64 Insulated glass window with thermal break in thealuminum section. A typical hollow aluminum

section is used as the spacer between the two panes of the doubleglazing. The frame of the window has two brown plastic bars toreduce extensively the heat conduction. Source: Hueck

Fig. 2.66 Wood-aluminum window system from Schuco’sComex 515 system. Source: Schuco

Fig. 2.65 Extruded spacers for the double glazed windows shown in Fig. 2.64. Source: Erbsloh-Aluminium

and undulating structures can be produced eco-nomically.Roller shutter and sectional doors in extruded

aluminum sections for fire stations and hospitalsand transport companies (Fig. 2.69) also dependon the beneficial properties of the alloys used.Aluminum shutter doors last longer and are

more stable than those produced in plastic. Ex-truded aluminum sections are usually used forthe closures of flat roofs and frequently for win-dowsills on house external walls. Extruded sec-tions are valued in buildings, and the interna-tional development of buildings shows acorresponding increase in the use of aluminumfor architectural applications.The refurbishment of curtain walling, win-

dows, and doors can produce large quantities ofaluminum as building scrap. This scrap can beeasily melted like that from machines, automo-biles, and rolling stock, and converted to sec-


Fig. 2.67 Conservatory extension in extruded and thermallybroken aluminum sections. Source: Sykon-Sys-

tems

Fig. 2.68 House with conservatory-type construction basedon aluminum extruded sections. Source: Sykon-

Systems

Fig. 2.69 Roller shutter door in extruded aluminum sec-tions. Source: Alusuisse

Fig. 2.70 Movable stairs for embarkation and disembarka-tion from aircraft at airports manufactured in ex-

truded aluminum sections. Source: Alusuisse

ondary aluminum. Melt refining, alloying cor-rection including optimum degassing andcontinuous grain refinement during the log cast-ing produce a quality that can hardly be distin-guished from primary aluminum. The aluminumalloys produced by remelting can be reused as abuilding material without restriction.

Civil engineering covers the area betweenmachinery and buildings. Design with metallicmaterials including, for example, iron and alu-minum alloys, predominates. Civil engineeringconstruction includes all types of bridges, shipjetties, railway station supporting structures, in-dustrial greenhouses, airport building, lifts andindustrial transport systems, parabolic reflectors

for flattop antennae for telecommunications,movable external and industrial steps, and signgantries on main roads and freeways, as well asoffshore plants including oil platforms with hel-icopter landing stages and so forth.The use of aluminum alloys for load-carrying

designs has proved successful for specific ap-plications. The use of these alloys in civil en-gineering is specifically linked to their proper-ties, including low density, acceptablemechanical properties, good corrosion resis-tance, and good workability in the production ofextruded profiles matched to both application


Fig. 2.71 Industrial stairs manufactured in extruded alumi-num sections including those shown in Fig. 2.72.

Source: Alusuisse

Fig. 2.72 Extruded aluminum sections for the manufactureof stairs and landing ramps. The bottom large pro-

file had a width of 600 mm and a height of 28 mm. Source:Alusuisse

Fig. 2.73 Application of extruded sections in AlMgSi0.5 fortransport systems in production applications and

warehouses. (a) A multicore hollow section for the rail of theoverhead conveyor of an assembly line (Alusuisse, Cie Francaisdes Convoyeurs) and (b) part of a transport line in extruded sec-tions for a modular transfer system. Source: Alusuisse/Bosch


Fig. 2.75 Assembly of the supporting profiles shown in Fig. 2.74 for the helicopter landing platform. Source: Alusuisse

Fig. 2.74 Helicopter landing platform manufactured from aluminum alloys with the multicore large section shown as the supportingprofile with multifunctions including integrated fire extinguisher foam pipe in the upper part of the section. Source:

Alusuisse

and loading. The aluminum semifinished prod-uct supplies a specialized market, although theuse of aluminum-base building materials is notso marked by spectacular designs and buildingsas is steel [Alp 94]. However, aluminum pedes-trian bridges, pedestrian drawbridges as well asgangways for ships, planking for quays and, inparticular, the Bailey bridges built in large num-

bers in West Germany in the 1960s in extrudedAlZn4.5Mg1 and AlMgSi1 bear impressive wit-ness to the advantageous use of aluminum alloysin specific cases. Equally, the use of extrudedaluminum sections in civil engineering is ver-satile, for example, the manufacture of movablesteps for airports and static industrial steps ascan be seen in Fig. 2.70 to 2.72. Extruded sec-


tions are also suitable for the manufacture ofconveyor systems (Fig. 2.73). The load carryingparts of marquees are usually made from ex-truded aluminum semifinished products, andmovable lifting platforms depend on their lighttelescopic aluminum arms. Even in undergroundworkings, reusable extruded aluminum form-work is preferred.For some time, aluminum large-scale con-

structions have been used in offshore applica-tions. Their use for accommodation modulesand helicopter landing decks, as shown in Fig.2.74, is related to the good physical and, inthe marine atmosphere, good corrosion resis-tance of the aluminum alloys used along withthe good assembly options of the large alu-minum sections and, thus, the favorable assem-bly costs. The helicopter landing deck in Fig.2.74 and 2.75 gives an impressive illustrationof this. Similar advantages are shown by theuse of extruded semifinished products in suit-able alloys for display signs on freeways andmain roads in the salt-laden atmosphere duringthe winter.

Extruded Products fromMaterials with a WorkingTemperature Range of 600to 1300 !C

Martin Bauser*

2.3 Copper Alloy Extruded Products

The temperatures used for the extrusion ofcopper alloys are 600 to 900 !C, significantlyhigher than those for aluminum alloys. Conse-quently, only semifinished products with simplercross-sectional geometries and thicker-walledsections can be produced because of the moresevere thermal loading of the shape-producingtools. Whereas extruded sections form the“lion’s share” of all extruded aluminum sec-

*Extruded Products from Materials with a Working Tem-perature Range of 600 to 1300 !C, Martin Bauser

tions, with copper alloys extrusion is used inmost cases as the preliminary step for subse-quent cold-drawing operations (with intermedi-ate annealing when necessary), which producethe finished dimensions of the required productssold by the semifinished product plant—bar,wire, section, and tube.The German standards list almost 90 wrought

copper alloys. In addition, there are numerousspecial custom alloys. This clearly illustrates thewide range of alloys and the fine differentiationto be found in copper and copper alloy specifi-cations. This, together with the large dimen-sional range of the semifinished products pro-duced by section and tube extrusion, makes itimpossible to describe all applications.The copper alloys are divided into the groups:

! Pure copper! Low-alloy copper! Copper zinc alloys (brass), also with addi-tional elements (special brass)

! Copper-tin alloys (tin bronze)! Copper-aluminum alloys (aluminum bronzes)! Copper-nickel alloys! Copper-nickel-zinc alloys (German silver)The high electrical and thermal conductiv-

ity—for pure copper, both are the highest of allmetals—the alloy dependent more or less goodworkability at room temperature (cold worka-bility) or at high temperature (hot workability),the corrosion resistance against different media,and the decorative appearance are decisive fac-tors in the selection of suitable alloys. With thiswide range of positive properties, extruded cop-per alloys can be found in an extremely widerange of industrial products—often only as a fewindividual parts such as electrical contacts inhousehold machines. Copper alloys form themajor component in only a few products, forexample, bathroom fittings, some decorativemetal products, or brass instruments.In the past few decades, a large part of the

market for copper alloys has been partly or com-pletely lost. One example is cutlery, which pre-viously was largely made from silver or chro-mium-plated brass and nickel silver and whichis now almost exclusively stainless steel. An-other example is in electronics, in which relaysfitted almost exclusively with copper alloys havebeen replaced as switching elements by elec-tronic components.Plastics are now used to a large extent for zip-

pers and ball point pens, although a small marketremains for high-value products. There are other


Fig. 2.76 Copper bus bars from extruded semifinished prod-ucts. Source: KM-Kabelmetall AG

Fig. 2.77 Bar, shaped bar, and turned components in free machining brass. Source: Wieland-Werke AG

examples of the loss of large-market segmentsto competitive materials, mainly plastic andsteels. However, new fields have opened forcopper alloys, for example, in module technol-ogy in computers, radio and television equip-ment, or in the central electronics in motor ve-hicles where a large number of connectors aremade from copper alloys.The most important industrial products for the

different semifinished product groups are de-scribed subsequently, without being comprehen-

sive. A useful detailed description of the differ-ent applications can be found in the informationliterature of the German Copper Institute (DKI).The majority of current carrying products

made in copper, the ideal electrical conductor,are wires produced by rolling processes. Squareand shaped bars as well as simple profiles forbus bars are, however, produced by extrusion(Fig. 2.76). They are used in electrical switchgear or for slip rings in electric motors. Hollowsections are used for water-cooled conductors inheavy duty transformers, in generator stators andstrong electromagnets in large research instal-lations.Bars made of copper tellurium (CuTe) and

copper sulphur (CuS) should be mentioned aslow-alloy copper machining variations, fromwhich, for example, welding torch nozzles andfittings are manufactured. This group of mate-rials includes age-hardening alloys that are usu-ally alloyed with chromium and zirconium andare associated with a high conductivity withgood wear resistance even at high temperatures.They are therefore suitable for welding elec-trodes for spot, seam, and butt welding. The useof welding robots in the automobile industry hassignificantly increased the demand for thesesemifinished products.Brass bars, sections, and wire are the most

important of the extruded products in the copperprocessing semifinished products industry. Par-ticular mention should be made of the lead-con-taining machining versions available in differentcompositions depending on the application. Thestandard bar for automatic lathes used to man-


Fig. 2.78 Brass extruded sections. Source: Wieland-WerkeAG

Fig. 2.79 Furniture fittings in extruded brass sections.Source: Wieland-Werke AG

Fig. 2.80 Brass section extruded sections. (a) Terminal blocks. (b) Lock cylinders. Source: Wieland-Werke AG

ufacture bolts, nuts, and other small parts isCuZn39Pb3 (Fig. 2.77).Household water fittings can be produced

from extruded bars of the hot-working alloyCuZn40Pb2 by hot stamping followed by ma-chining. Bars in other copper alloys includingspecial brasses and copper-nickel alloys are ma-chined to fixing elements and so forth where cor-rosive attack is feared.

The severe competition by plastic for the useof brass shaped wire for zippers has already beenmentioned. However, even today, metal is some-times preferred for high-quality applications.This also applies for many parts in equipment indaily use, where to some degree there has beena return to metallic materials, which retain theirshape even after prolonged use and also are lesslikely to break.


Fig. 2.81 Brass instrument made from extruded tombactubes. Source: Wieland-Werke AG

Fig. 2.82 Pressed products from extruded nickel-silver sec-tions. (a) Glass frames. (b) Drafting instruments.

Source: Wieland-Werke AG

Windows and facades are made from sheetand sections of special brass alloys(CuZn40Pb2) for specific requirements; this isnaturally not an inexpensive option (Fig. 2.78).However, copper-zinc alloys are often found inthe form of sections for furniture fittings andstair banister rails and tubes for light fittings aswell as many other products in the metal goodsindustry (Fig. 2.79).Brass sections are, moreover, used in terminal

blocks for electrical connections (usually sup-plied in long strips) and in lock cylinders (Fig.2.80). Bars and sections are supplied for equip-ment manufacture in special brasses matched tothe application.Copper-zinc alloys with high copper content

(tombac) can be easily cold worked. Brass in-struments are predominantly made from thesealloys (CuZn28–33). They have no competition,not only because of their excellent red-yellowcolor and their hygienic properties, but also be-cause of their good workability. Tubes aremainly used for this application as well as sheetand bars (Fig. 2.81).Nickel-silver alloys have a special role in op-

tics and fine machinery, for example, draftinginstruments and spectacle parts (hinges andframes) (Fig. 2.82).These alloys are also appreciated in other ap-

plications. For example, model railway rails aremade from extruded nickel-silver wire. The al-most silver appearance of this group of materialsalong with the good workability (bending,

stamping and machining) are the decisive fac-tors in the selection of the material. Small sec-tions and shaped components are mainlybrought to the finished shape from round barsby section rolling and drawing because the al-loys are difficult to extrude.Tubes in the corrosion-resistant special brass

alloys (alloyed with aluminum or tin) predomi-nate in power station construction (mainly incondensers) and in contact with seawater (in de-salination plants). Copper-aluminum and cop-per-nickel alloy tubes are also used in these ap-plications.Bearing sleeves in special copper-zinc alloys

are used extensively in the manufacture of ma-


Fig. 2.84 Extruded and drawn copper tube in straight lengths and coils

Fig. 2.83 (a) Bearing bushings in extruded special brass. (b) As installed

chines, mechanical engineering, power stations,and automobiles because of their good wear andcorrosion resistance. They are also being usedto an increasing extent as piston gudgeon pinbearings in engine manufacture (Fig. 2.83).The largest use of copper tube extrusion by

far is the manufacture of copper tubes for do-mestic water tubes (Fig. 2.84). The oxygen-freecopper SFCu has gradually almost completelyreplaced steel and lead pipes since World War

II. Today, copper tubes are converted from theextruded shell to the finished product by numer-ous drawing operations on rotary drawing ma-chines. However, plastic pipes recently havestarted to compete against copper tube in low-quality water because of copper solubility andoccasional corrosive attack.Copper tubes have also made their mark in

heating and air conditioning applications wheretubes are used for under-floor heating, radiator


Fig. 2.86 (a) Tube coils and finned tubes in extruded copper tubes. (b) Test stand for finned tubes. Source: Wieland-Werke AG

Fig. 2.85 Domestic insulation and under-floor heating in extruded and drawn (plastic-insulated) copper tubes. Source: Wieland-Werke AG

connections, and tubes in air-conditioning plants(Fig. 2.85). The tubes are purchased in straightlengths or small coils from the semifinishedproduct manufacturer for domestic applications,although large coreless coils with a preferredweight of 130 kg are used for industrial appli-cations (Fig. 2.84).Finned tubes are more suited for heat ex-

changer tubes than tubes with smooth surfaces.Different fin shapes are formed from smooth

tubes on roll machines, depending on the appli-cation. These finned tubes are also made in othermaterials (special brasses and copper nickel) ifthe medium in which they are used is corrosive(Fig. 2.86).In sanitary applications, water outlet com-

ponents are preferred in lead-free brass tubes;this is also due to the outstanding platingcharacteristics with nickel and chromium (Fig.2.87).


Fig. 2.87 Water supplies and bath fittings in extruded lead-free brass tubes. Source: Wieland-Werke AG

Fig. 2.88 Manometer springs in extruded and drawn tin-bronze tubes. Source: Wieland-Werke AG

The pressure-gage springs shown in Fig. 2.88are manufactured from thin tin-bronze tubesproduced from extruded tubes by numerousdrawing operations with intermediate annealing.The use of copper alloys processed by the ex-

trusion press and subsequent processing plantsto bar, wire, section, and tube extend well be-yond the examples mentioned. These can, how-ever, serve as typical examples of the wide-rang-ing possibilities for the application of copper andits alloys.

2.4 Extruded Titanium Alloy Products

Titanium alloys possess, depending on the al-loy, good to high mechanical properties retained

for long periods up to 480 !C and short periodsup to 550 !C. In addition, they also have goodcorrosion resistance due to the formation of aresistant passive coating, a relatively low densityof 4.5 g/cm3 and an outstanding creep resistanceunder thermo-mechanical stresses. These prop-erties, which are described in more detail in thesection “Extrusion of Semifinished Products inTitanium Alloys,” ensure that these alloys areused as specific construction materials for high-operating-temperature applications.The starting material for construction appli-

cations can be produced as bar, tubes, and sec-tions using the standard extrusion processesused for iron alloys. The extrusion of semifin-ished products with dimensions close to the fin-ished size is possible but expensive. This is alsodescribed in the section “Extrusion of Semifin-ished Products in Titanium Alloys.”The manufacture of aircraft, spacecraft, and

rockets cannot be imagined without titanium al-loys. Extruded titanium alloy products are used,in particular, where weight reduction underthermo-mechanical loading is required, includ-ing turbine blades in jet engines. In addition,components in extruded titanium alloys are usedbecause of their high strength and low densityin aircraft undercarriage, in the manufacture ofhelicopters and in the automobile industry forthe manufacture of, for example, cardan shafts.Extruded tubes are used to transport aggressivemedia in the chemical industry as well as in themanufacture of chemical equipment, includingheat exchangers, pressure vessels, and in plantsthat operate with salt-containing liquids, for ex-


Fig. 2.89 Extruded stainless steel tubes. The thin wall sec-tions that can be seen under the extruded sections

are produced by roll forming. Source: Krupp-HoeschFig. 2.90 Special sections as support tubes in a walking

beam furnace for heating steel slabs

ample, saltwater. Their good skin compatibilityas well as their visual appearance makes ex-truded titanium alloys useful as the starting ma-terial for the manufacture of glass frames andwatch housings. For the same reason, titaniumalloys are used for the manufacture of implantsand surgical tools [Mec 80, Alp 94].Titanium alloys have certainly not reached

their full potential because of their good prop-erties. Their further development from the pointof view of even higher thermo-mechanical load-ing and more economic production will openother areas of application. Titanium alloys alsolend themselves to recycling.

2.5 Extruded Products in Iron Alloysand Other Hot-Working Alloys

Various hot-rolling processes threaten themarket in extruded iron alloy semifinished prod-ucts. Only a few segments remain for extrusion,where the geometry of the extrusion, the specialalloy, or the small demand is preferred to theother processes geared to high throughputs instandard alloys and standard shapes.Extruded volume steel tubes—previously the

staple extruded product—have not been pro-duced on presses for some time. The productionof round and shaped bars is also moving awayfrom extrusion.With stainless steels, high-alloy ferritic and

austenitic steels are extruded as tubes. Down-stream cold pilger and drawing operations bringthe tubes to the final dimensions required by thecustomer. The severe requirements associated

with corrosive media—frequently associatedwith high temperatures—are the reason stainlesssteels of suitable composition are used in thechemical and petrochemical industries, powerstations (both fossil fired and also nuclear), andin marine technology. Extremely high specifi-cations frequently have to be fulfilled and evi-dence of numerous quality tests provided be-cause of the high safety requirements and thelong service life demanded.The same hot-working processes used for

stainless steels are also used for nickel-alloytubes as well as high-alloy high hot strength ma-terials. However, in these applications, extrusionplays a significantly more important role thanwith stainless steels, because only small quan-tities in very precisely alloyed materials are usu-ally required and the price of the very high re-quirements is not the controlling factor.A wide range of applications of nickel alloys

is found in the chemical and petrochemical in-dustries, in turbine and jet engine manufacture,in aerospace, ship construction, and the food in-dustry.Whereas tubes produced by extrusion usually

consist of high-alloy and difficult to hot-workalloys, easily worked versions are preferred forthe extrusion of profiles to enable useful crosssections to be produced. The extrusion tempera-ture is approximately 1250 !C so that the shape-producing tools can withstand only low extru-sion pressures and are so deformed after onlyone extrusion that they have to be reworked.Subsequent stretching and correction operations,possibly calibration and brightening drawingoperations, give the section the final shape.Higher-alloyed and thus difficult to extrudestainless steels can be extruded only into thesimplest shapes (Fig. 2.89).


Fig. 2.91 Special sections as guide plates, guide wheels,scraper edges, and stringers for construction ma-

chinery. Source: Krupp-Hoesch

The application palette for these profiles is ex-tremely wide ranging. In the manufacturers’ bro-chures there are, for example, sections for ve-hicles (railway superstructure, automobiledoors, and valve blocks), ship construction, andelevator guides, to mention only a few. Figures2.90 and 2.91 give two examples.As with the tube manufacturers, the section

producers also prefer to use the more economichot-rolling process for suitable section geome-tries and quantities.

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