Revolution in steel-beam fabrication

The SBA from ZEMAN fundamentally changes the structural-steel fabrication process.

Based in Styria in southeastern Austria, ZEMAN has developed a fully automatedproduction line for practically any type of steel beam that includes add-on parts.The individual components arrive on a conveyor at one end, and emerge a shorttime later at the other end as a perfectly assembled steel beam that then onlyneeds to be given a protective coating and loaded onto a truck.

The ZEMAN company has made a clean break withthe conventional way of doing things. No matterwhether you look at rolled sections, welded membersor corrugated-web beams – until recently, the onlyway fabricators could put their steel beams together,anywhere in the world, was by hand. This means thattraditionally, structural-steel elements are assembledby manually welding on the headplates, baseplates,connection plates and whatever stiffeners may beneeded to meet structural-design requirements. Thereare several drawbacks to this: In Western countries,

this is no longer economically viable. More and morefirms have therefore relocated their production tolow-wage countries, only to find that problems withtechnical fulfilment, deadline-keeping and qualitycontrol often eat up much of the cost advantage. As a result, structural steel fabricators in Western Europehave increasingly lost ground to competitors fromfurther east. These, in turn, have to contend with aconstant shortage of qualified personnel, and withtheir frequent inability to meet the required qualitystandards.

Now Zeman has unveiled a fully automated pro-duction line that does away with all these drawbacks.It actually sounds almost too good to be true: TheSteel Beam Assembler (SBA) performs all the steps in-volved in fabricating a steel member, without anyoneneeding to lift a finger. Instead, computer-controlledrobots execute the CAD engineering drawings 1:1 –with no errors, and in a fraction of the time thatwould otherwise be needed. The first step is that aconveyor system feeds all the add-on parts into theproduction line past a high-powered scanner. This notonly detects the position of each of the parts, whichwill have been placed on the conveyor table at ran-dom, but also captures its actual dimensions andcompares these with the target values stated in theCAD drawings. This ensures that the specified toleran-ces are complied with. The scanner relays all thesedata to the positioning robot, in real-time. This robotnow has the job of picking up the parts one by one,and positioning them correctly on the steel beam. Ithas several different magnetic grippers with which itcan safely pick up the various add-on parts, which areof differing sizes and weights. If any parts come infrom the infeed table facing the wrong way, the posi-tioning robot can briefly set them down on a holdingdevice on the robot table, and then pick them upagain the right way round. Again, the positioningrobot handles these tasks much more quickly and accurately than a human ever could. There is no

longer any need for laborious measuring up, or forthe comparatively ‘fiddly’ job of manually attachingthe add-on parts. With diagonally arranged parts, too,the task of positioning these dimensionally accurately,and fitting them up in the correct positions, is alsocarried out smoothly and flawlessly. Angles, tappetsand frame corners are also no problem. In the case ofthick add-on parts and large weld-seams, it is impor-tant to pre-heat the parts to be joined. Otherwise themetal may be distorted, or stress cracking may occur.This pre-heating is also carried out by the positioningrobot, using a heat torch.

Once the plates are correctly placed on the steelbeam, one of the two welding robots comes into action, tack-welding the plates to the main memberin the order dictated by the positioning robot. If hig-her capacity and output are needed, the productionline can be designed with two parallel lines. In thisdual-line configuration, while the two welding robotsfinish welding the workpiece on one line the positio-ning robot can carry on working on the other. Thewelding robots are also equipped with all the neces-sary tools: welding torch, plasma cutting device andlaser measuring system. Changeover to whichevertool is needed is also performed fully automatically.The two welding robots are mounted on a shared longitudinal trackway, but can be separately control-led. For the transverse and vertical strokes, there are

The structural-steel fabrication process with conventional fabrication and with computer-comtrolled SBA.

two further traverse-axes for each robot. The verticalaxis also has a telescoping unit which enables the lineto be installed in production buildings of the usualheight. Each of the welding robots is also equippedwith laser measuring heads. This enables them to recognise the actual fit-up situation and compensatefor any weldment tolerances. And with the plasmacutting device, the robots can trim the edges readyfor large-volume welding seams, and make any ope-nings needed in the web, or cut-outs on the mem-bers. When the steel beam is finished, it emergesfrom the line via the unloading device. The line is designed in such a way that not even a power outagehas any damaging consequences: Once power hasbeen restored, work can resume unhindered.

This innovative technology, with its unbeatable advan-tages, is the outcome of many years’ work. For thewhole thing is perhaps not quite as simple as itsounds. It took nearly five years of research and deve-lopment, and 4.5 million euros, to get the SBA to thepoint where it was able to revolutionise the market.The Austrian Research Promotion Agency (FFG) alsoprovided financial support for the development work.The devil was not just in the detail, but in an endless

number of different details. Which is why on severalsub-projects, time after time, the verdict was: “Backto the drawing-board and start all over again”. Thiswas particularly true of the control software. Origi-nally, an Austrian specialist company had been con-tracted to do the programming. After the desiredsuccess failed to materialise, the contract went to afirm in Germany instead. There too, they had to giveup after a few months. “Finally, we took matters backinto our own hands and worked with four sub-pro-gramming firms”, recalls Ersoy Asil, the Technical Ma-nager for Mechanical Engineering at Zeman. Againand again, fundamental concepts had to be re-thought, and significant elements rejected. The pro-gramming work proved to be exceedingly complex:For a start, to make sure that the machine really doesdeliver maximum productivity there must not be anytiming overlaps between the two production lines. If there were, unwanted downtimes would be the result. This made it imperative to prevent any waitingtimes being caused by both production lines needingto use certain shared plant components (like the scan-ner or the positioning robot) at the same time. Havingtwo production lines also means twice the volume ofdata. Not only did the computing capacity of the

The principle: Computer-controlled robot arms execute the CAD engineering drawings 1:1. Without errors, and at record speed.

Positioning robotThis picks up the required componentswith precisefitting accuracy and positionsthem at their exact fitting location. Time-consuming weldment handling and cali-bration work are a thing of the past.

Welding robotOperates with constantly highwelding quality and at constantlyhigh speed. This is ensured by theautomatic welding-robot servicestation.

Modular design conceptEither one or two lines can beserved by one positioning robot,as required by the client and itsproduction needs.

Laser scannerDetects the components in anyposition and compares them withthe CAD data. Data transfer to the robots is effected in real-time(i.e. with no testing time).

program have to be increased, but a further difficultywas that many computational steps have to be execu-ted in parallel. With the technology available backwhen the project began, this presented a giant chal-lenge and also a very great risk. As practically all partsof the plant are in operation simultaneously, it wasalso necessary to ensure that the various robots donot intrude into each other’s territory and cause se-rious collisions. This collision test places a further mas-sive burden on the system’s computing capacity.

Now fully proven and perfected, the control program– called pro-FIT – is the centrepiece of the machine. Itconsists of several overlapping modules. The first ofthese is the clerical processing module, which prepa-res the production operation. This module defines theposition of each of the parts for attachment, and spe-cifies the welds etc. – in short: everything needed inconnection with the production operation. ModuleTwo is the control station. This is where the work is di-vided up efficiently between the plant control systemand the robots. This module continually gathers dataand passes it on to the appropriate locations, and re-gulates how the robots interoperate. The third mo-

dule is an extensive databank. It contains a huge library of ‘collected works’ about assembling steelmembers, and all the parameters used in production.These are the cornerstones needed for producingmany very different workpieces: machine parameters,welding parameters, approach strategies for the various robots, and so on.

When it came to the hardware, the amount of deve-lopment work involved was equally large. It began withthe infeed tables. When the plant has two productionlines, both of them use the same scanner. If the posi-tioning robot used by both lines is to be able to pick upthe necessary parts from both tables correctly, and thenplace them correctly (and within the tolerance limits)on the steel beam, the two infeed tables must be run-ning absolutely in parallel. Over a length of 30 metres,the maximum tolerance allowed here is just plus/minushalf a millimetre! The scanner itself comes from PlasmoIndustrietechnik and was specially developed for theSBA with assistance from Arsenal Research. The mainproblem here was the varying heights of the steel plates and tappets (4 to 250 mm), and the varyingwidths of the plates (up to 800 mm).

Faster than any human worker ever could: the SBA from ZEMAN fabricates steel elements in record time. And inoutstanding quality. The robot systems will execute your projects much faster and at far lower cost.

Firstly, standard solutions were not up to the task be-cause their sensors cannot focus accurately enough –the tolerance required in the measuring of the parts(< 0.2 mm) was impossible to obtain with conventio-nal industrial scanners. Secondly, the harsh workingconditions on the shopfloor at steel fabricators’, andthe need to operate so close to welding robots andexposed to metallic dust, presented further obstacles.Over very many series of tests, Plasmo and Arsenal Research finally found a system that met all the demands made of it. The principal hardware devel-oper, however, was ABB Robotics. As its name implies,this firm was responsible for the robots used. “ABBhas worked with us previously on a number of suc-cessful joint developments, with us covering all thedevelopment costs”, says Asil. For the welding tech-nology, his company turned to Fronius, and the linearguideway system is from Güdel.

As already mentioned, the machine is available as either a single or double-line installation. For the maximum beam-length of 16 metres, it is 62 metreslong. The length of any particular plant is easy towork out: beam-length x 3 plus approx. 15 metres.

The reason for the extra 15 m is that the three pro-duction zones – infeed, welding and outfeed – cannotbe lined up seamlessly behind one another. Turning tothe width, the prospective purchaser should allow for13.5 metres for a two-line plant, and just under eightmetres for a single-line one. At six metres, both versi-ons have the same height, however. Individual clientwishes also have an effect on the dimensions, ofcourse. This Austrian innovation has already genera-ted a great deal of interest. “We’ve been getting en-quiries from Europe, Russia, India, China, Korea, theUnited Arab Emirates, North and South America – infact, from all over the world”, says a contented Asil.For Zeman, this means a widening of its customerbase. Until now, the firm says that it has mainly beenpresent in the project field in growth markets such asRussia, Brazil or Southeast Asia. Thanks to the SBA,customers from hitherto underrepresented regions arenow knocking at Zeman’s door. No wonder, whenyou consider that the SBA’s 100 % automationmeans that high wage and ancillary labour costs etc.now play only a minor role. At a stroke, it makes industrial production in e.g. Western Europe muchmore competitive vis-à-vis rivals in Eastern Europe or

Asia. For western producers, the substantial reducti-ons in labour, energy and materials costs mean a shorter payback period. For low-wage countries, onthe other hand, the machine is attractive because itenables them to supply top-quality goods even wit-hout well-qualified personnel. This is why Asil is confident that in the next three years, Zeman will beselling a “double-digit number” of SBA installations.

Developments like the Steel Beam Assembler alsohave considerable local and regional significance.Scheifling, the village where the company is based, isnot exactly in the middle of an economically boomingregion. This means that innovative enterprises likeZeman make a particularly important contribution towards keeping and creating jobs in the area. To research and develop successfully, you need skilled,well-qualified people, hence Zeman’s determinationto slowly but steadily increase the size of its work-force. Furthermore, on its various different projectsthe firm works again and again with local partners.And last but definitely not least, the positive environ-mental aspects of the SBA also deserve mention:Being fully automated, it shortens throughput times,eliminates costly remedying of human errors etc., andthus cuts the consumption of energy and operatingresources and reduces noise exposure. It also makesmore sparing use of material resources, from whichthe environment obviously benefits.

It is quite possible to conceive of Zeman’s technologyfinding uses in other fields as well. One example ofthis would be for joining and welding truck frames. A lot of work is still needed before this will be feasi-ble, though, as the systems available at present couldonly handle a limited spectrum of parts, and only inlarger production runs. However, Zeman has a bighead-start in terms of sector-specific know-how. Andsecondly, this Austrian company has already provedmany times over that it can tackle even the most challenging assignments.

1. The benefits at a glance

The advantages of fully automated fabrication withthe Steel Beam Assembler (SBA) are plain to see:There is no need for manual measuring and markingout, as the machine detects every single position onits own. Because the robots both work on the sameweldment simultaneously, there are also no down-

times. The beam is automatically fed into the SBA,clamped, and fed out again after fabrication. Cranehandling is no longer necessary. Being fully automa-ted, the SBA naturally also delivers savings in manpo-wer costs. Labour input is minimised. In addition, allthe empirical values acquired over the course of manyyears’ structural steel fabrication experience are filedaway in a database, available for re-use on a hugerange of different projects. This enables the SBA to beused in situations where there would not be suffi-ciently skilled personnel available for manual fabrica-tion. The main way in which clients can save money atthe same time as increasing their capacity is becauseof the much shorter production times. Zeman promi-ses reductions of up to 85 percent here. Instead of atleast eight hours for a tonne of steel, it now takes justunder two hours for the beam to be completely finis-hed. This also cuts the energy costs. And as long asthe SBA is given the correct data, the result is not onlyof the very highest accuracy but also always of consis-tently high quality. This is taken care of by the controlsoftware, which was specially developed for the SBAand can import all the production data directly fromany standard CAD program. Human errors such asmisinterpretation, accidental confusing of compo-nents or other careless mistakes are thus now a thingof the past – as is the costly subsequent finishing-work necessitated by the errors inevitably made du-ring manual assembly. There is also no longer anyneed to rectify weld-seam defects. Because ultimately,not even a superbly well-trained specialist can everweld as precisely as a machine. The SBA enhances thewelding quality still further by automatically pre-hea-ting the weldment. After all, when higher-gradestructural steels are being welded, getting the perfectweld-seam depends upon ensuring uniform thermalinput. At the same time, this also protects the weld-ment from distortion and stress cracking. As if morethan enough precautions had not been taken already,both the engineering and detailing data and the indi-vidual production phases are monitored at all times –from when the components are fed into the installa-tion, all the way through to when they emerge as thefinished product. Thanks to the machine’s very greatflexibility, its spectrum of use ranges from one-off L4Lfabrication all the way down to single-item lots. Inprinciple, the SBA can handle all common beam for-mats: rolled sections, welded plate girders, taperedbeams or special formats such as Zeman SIN beams.Member heights range from 200 to 1560 mm, andthe lengths from 3000 to 16,000 mm.

2. Pioneering work with corrugated-webbeams, too

Unlike conventional rolled sections, in this type of I-section girder the web is not straight but is ‘corruga-ted’ in a wavy, sinusoidal shape. This means greaterstability at the same time as lower wall thicknesses. A corrugated profile has the big advantage that itsconstructional design in itself is sufficient to preventthe otherwise inevitable local bulging – and thus toprevent possible subsequent failure of the beam. Corrugated-web beams also save around 45 percentof the weight, with cost-savings to match. However,for a long time this cost advantage was largely for-feited due to the comparatively labour-intensive manual fabrication of these beams. Until twelve yearsago, that is, when Zeman caused some excitement inindustry circles with the world’s first fully automatedproduction line for beams of this type. Today, corruga-ted-web beams of between 330 and 1500 mm inwidth, and 4000 to 16,000 mm in length, can be manufactured 100 % automatically. The web itselfonly needs to be between 1.5 and 3 mm thick to obtain the desired loading capacity. With the largestpossible web height of 1.50 m, for example, clearspans of over 40 metres can be bridged. A further advantage: You no longer need to keep a wide varietyof different sections in stock. Web plate, in reels, andflanges in larger plate formats that can be cut tolength as necessary, are all that is needed for just-in-time production of any desired beam. Incidentally, thecorrugated-web beam technology from Zeman alsoserved as the basis for the recently unveiled SteelBeam Assembler.

3. An Austrian enterprise with a tradition of success

Hans Zeman founded Zeman-Stahlbau back in 1965.To begin with, his company – based in Austria’s sout-heastern province of Styria – mainly produced steelconstructions for industrial and warehouse buildings.

It later added trapezoidal sections, building a newproduction facility for this product line at another location in Scheifling in the early 1980s. As well as itsrange of offerings for the building-construction seg-ment, today the company also produces conveyor andplatform bridges for the oil industry, lifts, containers,machine frames and various other types of customsteel construction. As time went on, Zeman’s struc-tural-steel fabrication activities gave rise to its mecha-nical engineering division Zeman-Maschinenbau. Thisnew entity started by improving the roll-forming ma-chinery Zeman was using, and ended up specialisingin the construction of entire production lines. At thebeginning of the 1980s, the company developed andpatented buckle-free bending technology for trape-zoidal steel sections. By way of licensing agreementsand the sale of production lines using the technology,it has since been marketed all across Europe. Fully automated fabrication of corrugated-web beams,launched by Zeman twelve years ago, marks yet another highlight which the firm has brought to market.

Zeman today is an international corporate groupingwith more than 20 locations and a workforce of over600. Its product range takes in everything from plantand mechanical engineering for heavy industry tosales halls and warehouses and even architecturalsteel construction and sports facilities. The services itoffers in this connection include consulting and plan-ning as well as project implementation, fabricationand erection. Zeman also acts as a main contractorhere. Not only architects and customers rate its workvery highly: the company won the “European SteelDesign Award” for the control tower at Vienna Airport in 2005, and then again in 2007 for Europe’sbiggest undulating roof construction at the “Złote Tarasy Atrium” development in Warsaw.

Zentrale / main office: A-1120 Vienna, Austria, Schönbrunner Straße 213-215Phone: +43 1 81414 – 0, Fax: +43 1 8122713, e-mail: info@zeco.at, www.zebau.com