svetsaren nr 3. 2000

A W E L D I N G R E V I E W P U B L I S H E D B Y E S A B V O L. 5 5 N O. 3 2 0 0 0

Automotive &Transport

2 • Svetsaren nr 3 • 2000

Contents Vol. 54 No. 3 2000

Articles in Svetsaren may be reproduced without permission but with an acknowledgement to ESAB.

PublisherBertil Pekkari

EditorLennart Lundberg

Editorial committeeKlas Weman, Lars-Göran Eriksson, Johnny Sundin, Johan Elvander, Sten Wallin,

Bob Bitzky, Stan Ferree, Ben Altemühl, Manfred Funccius, Dave Meyer

AddressESAB AB, Box 8004, SE-402 77 Göteborg, Sweden

Internet addresshttp://www.esab.comE-mail: [email protected]

Printed in Sweden by Geson Skandiatryckeriet, Kungsbacka

A welding review published by ESAB AB, Sweden No. 3, 2000

Automotive and transport.Photo: Ingmar Jernberg, Bildbyrån i Göteborg.

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Welding LPG tankers the ESAB wayA complete package of ESAB consumablescontributes to the successful fabrication ofLPG tanks at the Gdynia Yard in Poland.

FILARC PZ6015R – The robot friendlycored wire (III)Focus on ESAB’s aim to work closely withclients on mechanisation projects to sharp-en their competitive edge.

ESAB’s submerged arc solution for efficient trailer beam fabricationReplacing old double headed single wireSAW installation with a new submerged arc welding system helps Metal Design andFabrication, MDF, to meet increasing demand for their products.

Newly-developed consumable makesthin-plate welding more effectiveThe new metal-cored wire OK Tubrod14.11 can cut cycle times and help stream-lining the robot welding of thin plate.

Stubends & SpatterShort news

ESAB pulsed gas-shielded metal arcbrazing of surface-coated sheetsGMA-brazing with ESAB Aristo 2000 andOK Autrod 19.30 gives the best quality andexcellent mechanical quality values.

The use of rutile cored wires for weldinghigh strength steel in crane fabricationOK Tubrod 15.09 rutile cored wire helpsimprove the allover welding productivity atDutch crane fabricator Huisman-Itrec.

The new ESAB EcoMig welding wireadopted by Fai Komatsu Industries forwelding its earth-moving equipmentAn ecological product like ESAB EcoMighelps FKI, as one of the first metal-mechanical companies in Italy, with the application for ISO 14000.

Welding hydraulic cylinders using OK Tubrod 14.11 and the MAG andMAG-tandem processHigh welding speeds with MAG weldingand increased productivity with the MAGtandem method using OK Tubrod 14.11metal-cored wire.

Svetsaren nr 3 • 2000 • 3

Welding LPG tankers the ESAB wayby Ben Altemühl, editor of Svetsaren, interviewing Stocznia Gdynia production management

ESAB is supplying the Gdynia Yard with a complete consumables packagefor welding gas tanks in NV 2-4 low-temperature steel.

AcknowledgementWe would like to thank the Gdynia production man-agement for allowing us to visit the yard and for provid-ing us with the information on which to base this arti-cle. We would especially like to thank Mr. Zenon Szy-manski (EWE*) and Mr. Marek Piechulski (EWE), thewelding engineers, for their co-operation and support.We also compliment our colleagues at ESAB Poland onthe marketing success achieved at the Gdynia yard.(*European Welding Engineer)

Stocznia GdyniaVisiting this immense shipyard, located in the Baltic portof Gdynia, and witnessing the enormous activity, the titleof the national anthem automatically springs to mind,“Jeszcze Polska nie zgine,≥a” – “Still Poland is not lost”.

The history of the Gdynia shipyard, founded in 1922,is associated in many ways with the 20th century miseryand uprising of the Polish nation as a whole. It was es-tablsihed in the roaring twenties with ship repairs andwas as hard hit as Poland itself by the Great Depression

that was soon to follow, smothering any attempt to trans-form itself into a fully-fledged new building yard. Itwould take a series of bankruptcies and re-starts undernew ownership before, at the end of the thirties, the firstGdynia-designed ships slid off the slipway.

The rapid growth of the Gdynia shipyard was dramat-ically hampered by the outbreak of World War II. StoczniaGdynia was placed under the management of DeutscheWerke Kiel AG and was once again transformed into abusy repair yard and submarine building centre.

In 1943 and 1944, allied bombing destroyed theshipyard almost completely. After Gdynia’s liberationby the Soviet and Polish Armies in 1945, the yard ren-dered all kinds of services, before it reached its presentform. Its portfolio of orders included chimney pipes fora portable stove and the repair of cars (among themthose powered by wood gas).

The shipyard went on to become the largest repairbase for the Polish fleet when merchant and naval ves-sels started coming back to Poland from their war-timewandering, along with the German ships given to Po-land as war reparation and the English and American


Figure 1. Blueprint of a DNV class 1A1 LPG tanker.

ships received from military stores. In the fifties and six-ties, the majority of the ships that were built were deliv-ered to USSR owners. Soon after, a new era dawnedwhen the series production of B-523 type cargo shipswas started, fulfilling the special requirements of Nor-wegian owners. From that time, Stocznia Gdynia hadaccess to its own design department and more andmore orders were also received from western countries.From the mid-sixties, Gdynia has broken records de-signing and delivering up to 117,000 tonne deadweightOBO carriers, liquid gas carriers with prismatic tanks,bulk carriers and bulk tankers. In 1970, shipyard work-ers in Gdynia, just like their colleagues in Gdansk,undertook, on behalf of the whole nation, a rebellionagainst the government. A monument still serves as areminder of the victims who were killed and injured.

In 1980, the powerful Solidarity movement wasborn in the neighbouring Lenin Shipyard in Gdansk,triggering martial law in 1981 but also political and so-cial changes, which led to today’s market economy.

Stocznia Gdynia is now one of the largest and mostprofitable European yards, exporting close to 100% of itsproducts to clients from all over the world. It is capableof building ships up to 400,000 dwt and consumes around150,000 tonnes of steel a year. It builds fishing trawlers,general cargo and multi-purpose container vessels, crudeand chemical tankers, OBO carriers, car carriers andlarge passenger ferries. The yard is ISO 9001 certifiedand has access to modern design and analysis tools suchas CAD/CAM, NAPA, Tribon and Foran systems.

LPG carriersAt the time of our visit, the construction of the first oftwo 50,000 tonne deadweight DNV class 1A1 LPGtankers was nearing completion. These ships have fourtank sections with a total capacity of 78,500 m3, each ofwhich consists of two independent prismatic tanks (seeFigures 1 and 2). The tanks have a double hull and aresurrounded by a safety barrier. The red lines in Figure 2indicate the use of DNV class NV 2-4 low-temperaturesteel for the tanks and the safety barrier, whereas thegreen lines represent standard shipbuilding grades ac-cording to the Polish Bureau of Shipping (A32 andD32). The tanks are designed for a service temperatureof –50ºC at an overpressure of 0.275 bar. The CVN re-quirement for the steel and the welds is 27J at –55ºC.

Table 1 shows the chemical and mechanical re-quirements for DNV NV 2-4. Plates according to NV 2-4 specification are purchased from the Polish steel man-ufacturer Huta Czestochowa in three thickness catego-ries; 12, 20 and 28 mm.

As can be seen from Figure 3, the carriers are con-structed in sections according to modern shipbuildingpractice involving panel fabrication, the construction ofsub-sections, the assembly of grand sections and the fi-nal connection of grand sections in the dock. Platescoloured red represent DNV NV2-4 steel and the greenones indicate standard shipbuilding steel. The hull sec-tions are welded together in the dock to form the hullof the ship. The tanks are completed at the yard beforebeing lowered into the hull. After this, the prefabricat-ed top side including the deck is attached, together withthe processing installations (Figure 4).

The welding of DNV NV 2-4 low-temperature steelAlthough steels according to DNV class NV2-4 are de-veloped for low-temperature service, they contain onlya small amount of alloying elements and have a rela-tively low carbon equivalent. In the thickness rangeused by the Gdynia Yard (12, 20 and 28 mm) to con-struct the tanks, no preheating is required. However, toavoid the loss of HAZ impact toughness, there are lim-itations to the heat input and the interpass temperature.

From the point of view of the weld metal, extra careis required to avoid the loss of low-temperature impacttoughness. The consumables used by the Gdynia Yard

Figure 2. Cross-section of an LPGtank consisting oftwo independentcompartments. Thered lines are DNVNV 2-4 class steeland the green linesare standard ship-building quality.

for welding DNV NV 2-4 steel fall into two categories;basic for SAW and MMA and rutile Ti-B micro-alloyedfor FCAW.

Basic consumables produce a low-oxygen ferriticweld metal, consisting mainly of large amounts of some-what soft grain boundary ferrite and acicular ferrite.The low-temperature toughness depends on the qualityof the soft grain boundary ferrite in the microstructureand is further improved by 2.5% Ni-alloying. The mi-crostructure and toughness can be spoilt in two ways.When the heat input is too low, bainite or martensitemay appear as a result of the overly rapid cooling of theweld. When it is too high, the ferrite becomes coarse.

For rutile, Ti-B micro-alloyed flux-cored wires, low-temperature toughness is based on the presence oflarge amounts of fine acicular ferrite. In line with basicconsumables, the micro-structure is spoilt when bainiteor martensite is introduced when the heat input is toolow (see Figure 5). With high heat inputs, however,

Figure 4. LPG carrier about half way through the productionprocess. On the left-hand side, the top side of the carrierhas been attached. On the right, the tanks (covered withinsulation material) are still visible.

grain boundary ferrite appears at the expense of acicu-lar ferrite, with an even more detrimental effect on thetoughness.

When it comes to the welding of DNV NV 2-4, thismeans that the heat input has to be within a certainrange to be assured of the correct weld microstructure.ESAB recommends a heat input range of 1 to 2.5kJ/mmfor the consumables described under the next heading“welding consumables”. The welding techniques thatare used to build up the joint differ from normal ship-building practice and are more in the direction of weld-ing for offshore fabrication. Although preheating is notrequired for DNV NV 2-4 (as with many offshore steelgrades), the interpass temperature must be limited. Fullweaving, a very common shipbuilding technique, shouldbe avoided as much as possible because it can take theheat input beyond critical levels. The split-weave orstringer bead technique, both offshore fabricationmethods, may be less productive, but it ensures the cor-rect weld microstructure with corresponding good low-temperature impact values.

ESAB has been involved in many LPG projects asa supplier of welding consumables and equipment. Inmany cases, the company has provided the welder withtraining and assistance in setting up suitable weldingprocedures. It has often proved necessary to instructwelders in the right techniques to obtain the desiredlow-temperature weld metal impact toughness. Specialsupport was given to Gdynia to get it started with thecored-wire welding of the LPG tanks of the carrierscurrently under construction.

Welding consumablesTo construct the tankers, an innumerable number ofpanels have to be fabricated, to be connected to sub-sections and grand sections and finally to arrive at the

Figure 3. Exploded view of the tanker, showing construc-tion stages.

Figure 5. CCT diagram of CMn-Ti-B weld metal.

%C %Si %Mn %S %P %N CE (C+Mn/10)<0.14 0.15-0.50 0.70-1.60 <0.035 <0.035 <0.009 <0.32

Rm Re A5 CVN/–55ºC(MPa) (MPa) (%) (J)

400-490 255* >24 >27

Table 1. Chemical composition andmechanical properties for DNV NV2–4 low-temperature steel.



dock assembly of grand sections. Various welding pro-cesses are applied. Wherever possible, mechanisedwelding is used for increased welding productivity, butmanual welding is obviously indispensable for fit-upwork and the connection of sub- and grand sections, aswell as in dock assembly. Three welding processes pre-vail; MMA, SAW and FCAW. For the LPG tanks inDNV NV 2-4 steel and the hybrid connections betweenthe tanks and the normal ship quality steel hull, theESAB consumables listed in Table 2 are used.

OK 73.68 is a basic, 2.5Ni-alloyed LMA electrodewith a recovery of 120%. It provides good impacttoughness, even in the vertical-up position.

FILARC PZ6116S is a rutile, all-positional coredwire with Ti-B micro-alloying (+1.5%Ni) for use in CO2shielding gas.

OK Flux 10.62 is a high basic agglomerated flux(basicity index 3.4), suitable for single and multi-runwelding in both butt and fillet welds. It has excellentslag detachability and smooth side-wall blending. Incombination with OK Autrod 12.32 (DIN: S3), it pro-duces good CVN impact properties down to –60ºC.

The typical all-weld metal chemical compositionand mechanical properties are shown in Table 3.

Fabrication weldingTwo main SAW applications can be found in the fabri-cation of panels. Figure 6 shows the attachment of pro-files using double-sided tandem welding with the SAW

combination OK Autrod 12.32/OK Flux 10.62. Figure 7shows the same wire/flux combination used with a trac-tor for shorter weld lengths.

Another important SAW application is the connec-tion of plates to panel walls with butt welds usingdouble-sided welding. Figure 12 gives a characteristicwelding procedure specification. Note the maximuminterpass temperature of 150ºC, which is stipulated forall welding of DNV NV 2-4.

MMA is applied to a limited extent only, mainly forfit-up work in the construction of the sub- and grandsections of the LPG tanks. Figure 8 shows MMA weld-ing with OK 73.68, a very versatile consumable for thiskind of work.

FCAW is being used increasingly to replace MMAin order to produce increased welding productivity, es-pecially in positional welding. It provides a fine sprayarc at all applicable welding currents, making it easy tocontrol the heat input in vertical-up welding and thewelding of root passes on ceramic backing strips, for ex-ample. It is used indoors for manual fit-up work (Figure9), as well as outside in the fabrication of sub-sections(Figure 10) and the connection of tank segments tocomplete tanks, where it is used for the main vertical as-sembly welds. The use of CO2 shielding gas makes thewire more suitable for work outside in windy conditionsthan types using Ar-based mixed gas. Figure 13 shows a

Figure 7. Single-sidedSAW welding with OK Autrod 12.32/OKFlux 10.62.

Figure 9.FCAW underCO2 gasprotectionwithPZ6116S.

Figure 10.OutdoorFCAW withPZ6116S.

Figure 11. LPGtank underconstruction.

Figure 6. Double-sided SAW weldingwith OK Autrod12.32/OK Flux 10.62.

Figure 8. MMA weldingwith OK 73.68.

%C %Mn %Si %Ni Rm Re A5 CVN/–60ºC(MPa) (MPa) (%) (J)

OK 73.68 0.05 1.0 0.35 2.4 610 520 26 105

PZ6116S 0.05 1.3 0.4 1.5 615 550 25 75OK Autrod 12.32/OK Flux 10.62 0.07 1.4 0.3 – 580 475 28 90


welding procedure specification for welding DNV NV2-4 in the PF position.

ConclusionESAB is supplying the Gdynia Yard with a completepackage of consumables for welding LPG tanks in

Figure 12. Figure 13.

DNV NV 2-4 low-temperature steel. The package in-cludes consumables for MMA, SAW and FCAW.ESAB’s assistance with educating the welders and theestablishment of welding procedures, in particular forFCAW, has contributed to the successful fabrication ofthe tanks.

For MMA OK 73.68 EN 499: E 46 6 2Ni B 32 H5 AWS A5.5: E8018-C1For FCAW PZ6116S EN 785: T 46 6 1.5Ni P C 1 H5 AWS A5.29: E81T1-K2 JFor SAW

OK Flux 10.62/ EN 756: S 46 6 FB S3SiOK Autrod 12.32

Table 2. ESAB welding consumables for DNV NV 2-4.

Table 3. All-weld metal chemical composition and mechanical properties of ESAB consumables for DNV NV 2-4.


FILARC PZ6105RThe robot-friendly cored wire by Tapio Huhtala, ESAB B.V., the Netherlands

In Svetsaren 98/3 and 00/1, we introduced PZ6105R, ESAB’s metal-cored wire for robotic welding, and described its use for the fabrication ofexcavator frames in medium to thick steel, as well as the fabrication ofthin-plate automotive components.This article focuses on ESAB’s aim to work closely with clients on differentprojects involving mechanisation in our desire to sharpen their competitiveedge. Some additional applications will be presented in the field of thin-plate welding, including new applications from the automotive industry.

The markets nowadays are becoming increasingly largeand transparent. This tendency offers commercial po-tential to individual fabricators, but at the same time itcan entail a threat. Established companies are experi-encing increasing competition from newcomers in theirbranch of industry operating at international level. Inorder to remain competitive, they have to re-assesstheir business and change their market approach. Theyfrequently conclude that a new growth strategy is im-peded by what are known as limiting factors which affect the way they run their company.

These limiting factors may be encountered in thesupply of raw materials, the availability of labour, pro-duction capacity, warehouse capacity, financing, marketdemand and the delivery of finished products to end users. A bottleneck in one or more of these links in theproduction and marketing chain may account for thedifference between success and failure for the wholecompany.

A shortage of skilled labour, for example, is a prob-lem many fabricators are coping with in today’s boom-ing economy. Being successful calls for a creative ap-proach when it comes to recruiting new staff, re-educating one’s own personnel, mechanisation, or evenoutsourcing work to specialist firms.

The same goes for stocks. The market demand mayjustify a higher stock level, but at the same time compa-nies are trying to minimise the amount of money invest-ed in stocks. Creative solutions are found in modernstock management systems such as EOQ (EconomicOrder Quantity), JIT (Just In Time) and MRP (Materi-als Requirement Planning).

In the area of financing, renting or leasing can beconsidered when traditional financing instruments rep-resent a limiting factor.

Welding, a necessary production step for many fabrica-tors, can also constitute a bottleneck in the productionchain. This bottleneck can be concentrated at the weld-ing station itself, but it is very often a combination offabrication steps associated with welding, such as highrepair and scrap rates.

Co-operation with fabricatorsESAB makes its knowledge of welded fabricationavailable to the automotive industry by participatingin projects that aim to increase the competitiveness ofindividual fabricators in this field. In the assessmentof the welding situation and the implementation ofmore productive solutions, always in close co-operation with the fabricator, different types of prob-lem emerge.

One that is more or less standard is the lack of timeon the part of the fabricator who is often caught up in avery tight production schedule. Further down the line,there may be preoccupations about running tests onproduction lines at the risk of causing unacceptabledowntime. Very often, the availability of a skilled robotprogrammer is a problem that stands in the way of ef-fective testing on the customer’s site.

ESAB has recognised these problems and has de-veloped its own test facilities to minimise on-site testingas far as possible and thereby the impact on thefabricator’s normal production set-up. When on-sitetesting becomes necessary, the type that has the least ef-fect is chosen, for example, by utilising the weekends orother times when regular production is stopped.

This working process is explained in more detailbelow.


Working process Phase 1

In every case, the projects begin with a thorough evalu-ation of the production situation by skilled people fromESAB working together with the fabricator. Subjectssuch as needs, requirements, determination of bottle-necks, limitations related to welding equipment andtorch positions, discussions about present problems andso on are covered.

When there is agreement that there are significantbenefits to be gained, the project proceeds into phasetwo.This consists of welding trials at one of our weldingapplication laboratories on samples supplied by the cli-ents.

Phase 2

At the present time, ESAB has two locations (Utrechtin the Netherlands and Göteborg in Sweden) wheremore advanced tests including robot welding can becarried out. During the tests, the fabricator’s situation iscopied as closely as possible. If, for example, the free-dom is given to test other gases, this is done to seewhether any additional benefits can be obtained. Quitefrequently, clients have a central gas network supplyinga specific shielding gas, so a change of shielding gas isthen out of the question.After the welding trials, the re-sults are carefully evaluated and reported back to theclients. Assistance with cost calculations can also beprovided in cases where sufficient information has beenreceived.

When the results of the welding trials show forsome reason that no additional benefits will be gainedby implementing the findings, the project is terminated.When the outcome is positive, it is up to the fabricatorto decide if and when he wants to move into phasethree, on-site testing. The major benefit provided byESAB by working in this way is, quite naturally, a min-imum impact on the company’s own production. Theonly risk the fabricator takes is the cost of the samplessent to the welding application laboratories.

Phase 3

During phase three, welding trials are performed onsite under ESAB’s guidance using the company’s ownequipment and new evaluations, based on the values

obtained, are made. The time span of the on-site testingvaries. Sometimes a short on-site test is followed by along-term one. After a careful evaluation of the datathat are obtained, it is up to the company to decidewhether or not to transfer its process.

Some examples are given below of projects carriedout using this approach. As many fabricators, especiallyin the automotive industry, are not keen on publishinginformation about their production, we refrain frommentioning the names of the companies involved.Moreover, all the data presented here are values ob-tained after phase two in the different projects, i.e. aftertests at our welding application laboratory in Utrecht.

Application 1Welding a safety component for trucksThe problem definition:• Lack of fusion caused by the torch being directed

more towards the inner ring. The reason for thistorch position is to avoid melting the outside edge ofthe sample

• The spatter level is too high, resulting in an undesir-able amount of post-weld grinding

• The productivity of the welding station is too low, i.e.it is a bottleneck in the production process

Figure 1 shows a cross-section of a safety compo-nent for trucks. The parent material is equal to St 37.2with an outer diameter of 100mm and a thickness of4.5mm. These parts have been welded with SG2-typesolid wire, diameter 1.2mm, using the pulse techniqueand a welding speed of 14.5 mm/s.

Like all the other tests described below, the applica-tion research was performed with an ABB IRB 1400welding robot and an ESAB Aristorob 500 powersource. Suitable parameters for welding the circularweld were found at 398A/6V/10m/min. at 25mm stick-out length. The travel speed obtained was 1.3m/min. Agas mixture of 90Ar/10CO2 was used as gas protection.

Figure 1. Safety component

Figure 2. Safety componentwelded with PZ6105R

Figure 3. Etched cross-section

Figure 4. Scaffolding component


The results showed a 38% increase in welding speedand the samples were free from spatter. The burn-inprofile and bead profile were good without any meltingof outer edges, suggesting significant potential for aproductivity increase as a result of a reduced scrap andrepair rate.

Figure 2 shows the component after being weldedwith PZ6105R using the above-mentioned parameters.Figure 3 shows a cross-section of the weld. It can beseen that the weld is relatively flat with good penetra-tion, without melting the outer edge, in a series of testsrepeatedly meeting all the quality objectives set by theclient.

Application 2Welding scaffoldingThe problem definition:• Excessive spatter level necessitating post-weld clean-

ing• The productivity of the welding station is too low, i.e.

it is a bottleneck in production

A non-automotive, yet interesting, application, involv-ing the welding of 2.2mm thick tubes to produce scaf-folding. The client uses robot welding together with1.0mm diameter solid wire under 80/20 Ar/CO2 gasprotection, using conventional MIG power sources.

Figure 4 shows a reference sample taken from theclient’s production. The numbers indicate the differenttypes of weld, whereas the letters show the locationsfrom which transverse cross-sections were taken fromsamples produced with PZ6105R. Figures 5 to 7 showthe solid-wire welds corresponding to the numbers 1 to3 in Figure 4.

The same welds, now performed with PZ6105R us-ing the same shielding gas, are shown in Figures 8 to 10.The welds are flatter and spatter is virtually absent. Atransverse cross-section taken from location A and rep-resentative of the type of penetration obtained is shownin Figure 11.

The results showed that the spatter could be almosteliminated. There is potential for increasing productiv-ity by more than 40% and a corresponding cost reduc-tion/ sample of more than 20%.

Figures 12a, b and c show the results of tests per-formed on another scaffolding component from thesame customer. The problem definition is the same asfor the previously mentioned component.

Equally good results were obtained in terms ofspatter. The productivity increase and reduction in pro-duction costs were even larger than the above-mentioned figures.

Figures 5,6,7. Solid wire welds1,2,3

Figures 8,9,10. Welds 1,2,3made with PZ6105R.

Figure 11. Etchedcross-section A-Aof a scaffoldingcomponent weldedwith PZ6105R.

Figures 12a,12b,12c. Anothercomponent (12a) welded withsolid wire (12b) and withPZ6105R (12c).


Application 3Welding tow eyelets and hooks for exhaustpipesProblem definition:• Productivity at the welding station is too low• The welding station is a bottleneck in the production

processThe third example deals with the welding of tow

eyelets with a plate thickness of 2mm (Figure 13). Thesteel bar which has to be attached has a diameter of12mm. Oil residue is frequently present on the 2mmplate.This work is currently done at a robot station with1.2mm diameter solid wire under 90Ar/7.5CO2/2.5O2,using conventional MIG power sources. The welding isdone in the PB position at a travel speed of 0.8–1.0m/min.

To perform the tests, a fixture was constructed forthe components (Figure 14). The letters indicate the lo-cations of the different welds. Figure 15 shows a trans-verse cross-section of weld B. It is clear that the weldquality is good. Suitable parameters were found around290A/23V/8 m/min. at a travel speed of approximately1.62 m/min. for welds A to C (20mm stickout), account-ing for an increase in travel speed of around 70%.

In combination with the above-mentioned applica-tion, another welding trial was conducted on hooks forexhaust pipe systems (Figure 16). This component isproduced at another robot station. It was not as urgentfor the customer to increase productivity at this stationas it was in the previous application. These tests wereconducted for future needs. The welding was done inthe PB and PG positions. Currently, solid wire � 1.2mmis used under 90Ar/7.5CO2/2.5O2 shielding gas. The

welding speed for the major long weld deposited in thePG position is 1.2 m/min.

Welding speeds in the range of 1.4–2.0.m/min wereachieved. The higher welding speed is valid for the longweld deposited in the PG position.

SummaryThe competition within industry is increasing, forcingcompanies to re-assess their business situation. Identi-fying limiting factors has become increasingly impor-tant. There are some problems that companies have todeal with when working with process improvements.They include lack of time, limited access to robots andprogrammers and the risk of lost production associatedwith running on-site tests during normal productiontime. ESAB has recognised these problems and workstogether with a number of clients in a flexible manner,offering minimised risk levels and increasing the prob-ability of success for clients.

For more information, please contact your localESAB organisation.

About the author

Tapio Huhtala is a product manager for unalloyed coredwires at ESAB B.V. in Utrecht in the Netherlands. Hejoined ESAB in 1993 and worked as a research metallur-gist in Goteborg until 1998.

Figures 13,14. Tow eyelet weldedwith solid wire and special fixture (14)for robotic tests with PZ6105R.

Figure 15. Cross section of weld B infigure 14.

Figure 16. Exhaust pipe hook


ESAB’s submerged arc solution forefficient trailer beam fabrication by Shaun Studholme and Derek Harvey – ESAB UK Ltd.

Metal Design and Fabrication, MDF, a trailer beam fabricator located in Antrim, Northern Ireland has obtained amajor increase in manufacturing outputby installing a custom made ESAB twinwire submerged arc welding systemusing OK Tubrod 14.00S metal coredwire with OK 10.71 agglomerated flux.

MDFMDF is a successful fabricator of trailer beams supply-ing frames to the major truck manufacturers in the UKas well as several countries on the European mainlandand are expanding rapidly.

To enable them to meet the increasing demand fortheir products, they decided to invest in a new sub-merged arc welding system for the fabrication of theirmainstream beams (figure 1), replacing their old doubleheaded single wire SAW installation using solid wire.

ESAB were awarded the contract after having pre-sented a solution that provided increased welding pro-ductivity as well as flexibility for the various designs ofbeams that MDF produce. Along with the installationof the new system, MDF reorganised their workshoplayout to optimise the efficient supply of beam compo-

nents to the welding station. Having used the new weld-ing unit for over a year, MDF claim that it is 3 to 4 timesmore productive than before, depending on the type oftrailer beam.

Double headed twin-arc SAW installationThe manipulator type MBVA 550 is mounted on a com-pact track, which requires a minimum amount of floorspace. It is sited so that the unit can travel along thelength of two side-by-side welding fixtures, welding oneassembly while the second unit jig is being unloadedand re-loaded. The column is fitted with 180 degree ro-tation to allow for positioning the boom over the fix-tures. The carriage carries a special OPC flux recoveryunit, and a TPC 75 pressure tank for delivering flux tothe two A6 welding heads, which deliver twin wires viabent D20 contact tubes. The arrangement allows forwelding web widths from 70mm to 800mm. A VEC mo-tor giving a tacho feedback into a PEG 1 control unitprovides accurate carriage travel along the track that islong enough to cover the fixture and parking areas.

The welding heads are positioned and guided alongthe length of the beam by GMD guidance units, whichcontrol the vertical slides, and complete horizontal car-riage allowing for motorised movement along the fulllength of the boom.

Welding voltage and current are pre-set and contin-ually monitored by two PEG 1 control units, giving con-stant stable conditions.

For safety and optimum use of space, the weldingand control cables are housed in a cable chain that is fit-ted within the rail assembly. The cables run the full

Figure 1. MDF’s custom made ESAB twin wire submergedarc welding system. At the request of MDF, part of thephotograph has been blurred.


OK Tubrod 14.00S (with OK Flux 10.71) AWS A5.17-89: F7A2-EC1OK Flux 10.71 EN 765: S A AB 1 67 AC H5

length of the track, between the carriage and floor sitedLAE welding power sources.

Apart from the welding parameters, all controls arefitted on a remote control unit, which can be hand-heldby the operator while positioning and welding thebeams.

Welding consumablesIncluded in ESAB’s proposal was the use of the coredwire/flux combination OK Tubrod 14.00S-Ø2.4mm/OK Flux 10.71, equipping MDF’s SAW installation withthis proven consumable package for high speed filletwelding.

OK Tubrod 14.00S is a metal cored wire providinga deposition rate that is up to 20% higher than a solidwire of the same diameter, depending on the weldingapplication. It has been designed for use with OK Flux10.71, an agglomerated, aluminate-basic flux that isslightly Si and Mn alloying. Table. 1 gives the wire andflux classifications.

The combination is used when high integrity weld-ed joints are required in mild and medium tensile steels,providing an excellent bead appearance in single andmulti-layer butt and fillet welds with good impacttoughness down to –20ºC. It is suited for both singlewire and twin wire applications. The slag detachabilityis good, also in narrow joints.

The MDF application consists of the simultaneouswelding of two fillet welds with twin arc heads in the PBposition (see photo). The flat strip varies in thicknessfrom 4–8mm, whereas the vertical plates have a thick-ness between 8–20mm.

One advantage reported by MDF is that thewire/flux combination gives a round, but relatively flatbead penetration. Even when welding 8mm sheet, noburn-through problems occur, as encountered regularlywith the old station using solid wire.

A second benefit is that the various beams, regard-less the material thickness, can be welded at the sameparameter setting of 580A/29V and 130cm/min. travelspeed. This avoids the time consuming resetting of pa-rameters which adversely effects the production effi-ciency.

A third advantage reported is the better slag de-tachability, saving time in the manual removal of slag.

Further, MDF are very satisfied with the appear-ance of the welds especially the blending of the toes.The latter is crucial for trucks, since the dynamic loadthey are subjected to can lead to the formation of fa-tigue cracks when welds do not smoothly blend with theplate material.

Coupled with the greatly increased productivitythese benefits have helped to ensure that MDF remainsat the leading edge of trailer beam manufacture.

Figure 2. SAW with OK Tubrod 14.00S/OK Flux 10.71.Note that the slag is self releasing.

Figure 3. The self-released slag is easily removed.

Figure 4. Bead appearance. The standing fillet weld is flatwith a smooth blending of the toes.

About the authorsShaun Studholme, Product Manager, Cored Wires inESAB Group (UK) Ltd. He is responsible for cored wiremarketing and is based at Waltham Cross, UK.

Derek Harvey joined ESAB in 1983 as a Service Engi-neer, and became a member of the arc-equipment techni-cal department, based at Waltham Cross some years later. In 1993 he was appointed Sales Manager for Weld-ing automation Equipment and has responsibility for thesale of automatic SAW, MIG/MAG, and mechanised TIGequipment.

Table 1. Wire and flux classifications.


Newly-developed consumablemakes thin-plate welding moreeffective by Lars-Erik Stridh, ESAB AB, Göteborg

As a result of increasingly fierce competition from low-cost countries,rapid changes are taking place within the welding industry in Europe.A large part of the heavy welding industry is moving its productioneastwards, to countries with low labour costs, leaving behind it industries with skilled and mechanised welding. Europe has a num-ber of major automotive producers with many suppliers, most ofwhom have introduced robotic welding into their production process.

The consumables these robots use for welding are gen-erally solid wire with a diameter of 1.0mm. The shield-ing gas is often a mixed gas with a third component tominimise spatter. Continuous developments are takingplace within automotive production when it comes tosystems for joining sheet metal. These systems includebonding, resistance welding, MIG soldering, laser weld-ing and closing-head rivets. Arc welding still maintainsa powerful position in present-day automotive produc-tion and, depending on the brand, there are betweenone and two kilograms of weld metal in every vehicle.

Robotic welding increases at a relatively constantrate every year. The number of arc welding robots risesby around 10% every year in Europe. In the automo-tive industry, these robots are usually included in ad-vanced cells containing several robots that work togeth-er in a production chain. In the fiercely competitive sit-uation that currently exists, it is vital for the automotiveindustry and its suppliers to make this production pro-cess as efficient as it can possibly be.

BackgroundThe requirements that are set for welding for differentcomponents for the automotive industry are naturallyrigorous.After all, the vehicles that are involved are go-ing to transport people and attempts are constantly be-ing made to find lighter materials to reduce the weight.This is done to economise on natural resources and cutfuel consumption, but, at the same time, the safety stan-dards for passengers are being constantly stepped up.The plate thicknesses are small and homogeneous wire

is generally used. One of the problem areas is penetra-tion. The measurement precision of the sheet-metalcomponents which are going to be welded together var-ies. This means that the joints are slightly different andtheir position varies somewhat.This is a problem, as thearc from a � 1mm homogeneous wire has a small diam-eter, making the penetration profile narrow and there-by sensitive to joint tolerances. In practice, this meansthat welding defects such as incomplete penetration orperforation easily occur.

Interior from the robot cell in Göteborg where a frontsuspension part is test welded with OK Tubrod 14.11 Ø 1.4 mm.


It is also important that the transition between theparent metal and the weld run is uniform and smooth.In other words, the fatigue strength must be high. Thischaracteristic is becoming increasingly important asmore and more high strength steel is being used instructures to save weight by reducing plate thickness

Productivity and cycle times in the robot cell arevery important when it comes to keeping costs down.As a result, attempts are made to increase the weldingspeed whenever possible. This leads to another impor-tant factor – the hardness of the weld metal and theHAZ (heat affected zone). The heat that develops inthe arc from a homogeneous wire is relatively low andthis results in rapid cooling and the risk that the hard-ness will be too high and the weld joint will therefore bebrittle.

New approachESAB’s process know-how and collaboration with dif-ferent suppliers to the automotive industry and with theautomotive industry directly, in combination with thesecustomers’ production expertise, has resulted in a newconcept for welding thin plate, which can now be usedsuccessfully within the automotive industry.

When it comes to welding thin plate, most peopleassume that they should use solid wire with a small di-ameter. Few of them consider using a metal-cored wirewith a larger diameter. However, this is exactly wheredevelopments have led – namely to robot welding usinga metal-cored wire with a diameter of 1.4mm.

The product is called OK Tubrod 14.11. It is a weld-ing wire that has been developed to suit robot welding.It is therefore easy to feed, as it must not cause feed dis-ruptions. The arc is stable and produces a minimum ofspatter and one very important characteristic is that it ispossible to weld with high currents and relatively lowarc voltage with no reduction in arc stability. This hasbeen made possible by target-oriented developmentwork.

Customer applicationsThe following example illustrates the advantages. Asupplier to the automotive industry welds many differ-ent small components. The company uses � 1.0mm sol-id wire and, to obtain the widest possible penetration, ituses pure carbon dioxide as the shielding gas. Six robotswork together in a robot cell. A centrally-located weld-ing table is filled with six identical components and itthen rotates one-sixth of a revolution after each weld-ing operation. The six robots weld different parts of thecomponent simultaneously, which means that the weld-ing times are different and some robots have to wait afew seconds while the others finish welding.The waitingtimes are not that long – anything from four to ten sec-onds – but, in view of the fact that there are six weldingoperations in the total cycle, the total waiting time canbe a minute or two. The refilling time in the cell is shortand the cell welds continuously, so there can be as muchas an hour of non-productive time during the course of

a day. Over a month, this makes 20 hours. The produc-tion cost in an uncomplicated robot cell with one robot,one positioner and one operator is around SEK 1,000an hour.The production cost in a complicated robot cellwith six robots is naturally much higher. So the cost ofthis ”waiting time” is very high.

As this company is currently operating at maximumcapacity when it comes to what solid wire can achievewhile maintaining approved quality levels, tests wereconducted using OK Tubrod 14.11, � 1.4mm. In thetests that were conducted using a robot at the ESABWelding Centre in Göteborg, it was found that thewelding speed could be increased from 18 mm/sec forsolid wire to 30 mm/sec for flux-cored wire. This meansthat the whole of the waiting time described abovecould be eliminated for some robots and that the totalcycle time could also be reduced by synchronising thewelding speed of the robots.

The photographs show examples of the surface ap-pearance and penetration during these welding tests.

Another example from another supplier who alsowelds components for the automotive industry is shown

A very common joint; overlap. Plate thickness is 1.5mmand welding speed in this case 32 mm/sec.

Example of the very good penetration also at high weldingspeeds, in this case 27 mm/sec.


Part from car industry Weld length: 31 cm.

Solid wire OK 14.11 Difference

Cycle time (s) 58.6 40 –31%Welding speed (m/min) 0.6 1.5 +150%Welding time (s) 31 12.4 –60%Robot motion time (s) 27.6 27.6

Cycle time/unit (s) 58.6 40 –31%Reloading time (s) 10 10Number of units/h 52 72 +38%

OK 14.11 Solid wire

Wire consumed/unit (kg/unit) 0.014 0.014Wire price (£/kg) 4:36 0:77Wire cost (£/unit) 0:0612 0:0106Shielding gas consumed (m3/unit) 0.014 0.018Shielding gas price (£/m3) 2:83 2:47Shielding gas cost (£/unit) 0:0400 0:0400Energy cost (£/unit) 0:0047 0:0047Robot + operator cost (£/h) 103:06 103:06Robot + operatos cost (£/unit) 1:43 1:68Total cost (£/unit) 1:55 1:73

in the table. In this table, the cost is presented for theprevious method of welding with 1.0mm solid wire andis compared with the results for the same componentusing OK Tubrod 14.11, Ø1.4mm cored wire.

AdvantagesThe reason why the use of this relatively thick, metal-cored wire, OK Tubrod 14.11, has been given such agood reception is quite naturally largely due to the op-portunity to reduce the total cost by cutting the cycletimes as a result of the improvement in productivity. Inaddition, the welding quality is also enhanced. The rungeometry produces a smooth, fine transition to the par-ent metal. As penetration is wider and more reliable,welding is now also more tolerant as far as gap varia-tions are concerned, thereby reducing the number ofwelding defects and the number of rejects. This repre-sents savings that directly affect the profit margin.Whatis more, the amount of spatter from the wire is also low-er, thereby reducing the number of stoppages to cleanfixtures. Furthermore, the cleaning of gas hoods whichthe robot performs at the cleaning station is reduced by50%, with the result that the cycle time is even furtherreduced.

SummaryThere is excellent potential for streamlining the robotwelding of thin plate This applies particularly to the automotive industry and its suppliers who demand high

productivity and high and reproducible quality. It is,however, important, when introducing a new consum-able for welding which can cut cycle times, that thewhole production chain is taken into account, in orderto avoid creating a bottleneck further down the chainand thereby losing the savings that are made in thewelding cell. By planning the welding operation care-fully and adapting the remainder of the productionchain, a great deal of money can be saved and the auto-motive industry in Europe can maintain its competitiveedge and keep jobs in Europe.

About the authorsLars-Erik Stridh, EWE, graduated from Bergsskolan in1982. He worked three years as a welding engineer at arepair and maintenance company in Göteborg and afterthat 13 years as product manager for flux cored wires ata competitive company. Lars-Erik Stridh joined ESAB in1999, is based in Göteborg but works on ESAB’s totalmarket.


Great success withthe new ProcessControl system fromESAB

The new PEH Process Controllerhas been well received by thewelding market. So far, more then1000 units have been delivered.

The PEH Process Controller isnot only taking care of the weldingparameters such as current, voltageand travel speed but optimises thebest welding performance for thewelding parameters, wire diameter,start, stop and the material to bewelded. The unit has a user-friendly micro processor and a bigdisplay on which all the parame-ters are showed. The unit can alsocalculate the heat input and showit on its display before and duringwelding. It is possible to pre-set allparameters before welding andstore ten different welding param-eter set.

The PEH Process Controllerhas several menus; two for thewelder and two for set-up and in-stallation. This process controller issuccessfully used for stationarywelding heads, tractors, column &booms and special customised so-lutions.

Stub-ends&Spatter

There is a growing interest in theuse of natural gas as a source ofenergy. Much of the gas resourcesin the world are, however, general-ly located far from the main con-sumption areas. For this reason theneed for transportation and stor-age of gas is increasing in manyparts of the world.

ESAB has an impressing trackreference in supplying weldingconsumables and equipment forlarge LNG tank constructions. Themajority of the large land basedtanks are constructed in 9%Nisteel and the gas is stored in a liq-uefied condition at temperaturesbelow –105°C.

In May 2000 ESAB receivedan order for consumables andwelding equipment for the weld-ing of land based LNG tanks(140.000 m3 each) for a gas termi-

nal in Izmir, Turkey. (The contrac-tor is EgeGaz and the project man-agement is made by CB&I.)

The consumables including theelectrode OK 92.45 (AWS 5.9ENiCrMo-3) as well as the fluxand solid wire combination OKFlux 10.16/OK Autrod 19.82 (AWS5.9 ER NiCrMo-3) have been sup-plied and a customer designedSAW equipment, Circotech, for the2G SAW welding inside the tank.

Would you like more informa-tion on these products, please contact ESAB at e-mail [email protected] or fax + 46 31 509 170.

ESAB supplies consumables and equipment foryet another LNG storage tank project

PEH Process Controller.

Picture: Courtesy of CBkI

3 buttering layers withOK 92.05


ESAB Welding Equipment AB,Automation & Engineering, has established a partnership agree-ment with GEISMAR Société desAnciens Établissements in France,relating to the delivery of flash buttwelding machines for welding railprofiles and rail frogs.

GEISMAR has the know-how,resources and products in the fieldof joining of rails and frogs includ-ing equipment and processes need-ed to complete this process. Withthe ESAB welding equipment theirspecial market organisation can nowsupport and supply the customerswith complete lines for rail joining.

ESAB and GEISMAR receivedtheir first order as a result of this co-operation in 1998. The welding ma-chine was delivered to JR-West inOsaka, Japan in November of 1999and is now in full production.

Another two new contracts fordelivery year 2000 have beensigned. The first one for BulgarianState Railways with delivery at theend of June and the second to Lat-vian State Railways with delivery inNovember.

The parties are working closelytogether on new projects and thereare a number of even more promis-ing projects coming up within thenear future.

A three-layer buffer area waswelded onto the copper. The bufferlayer was ground to obtain a total70° wide angle and the root runwas then performed with OK 92.05� 2.5 mm. The joint was filled infour passes using 3.25 mm � elec-trodes. The interpass temperaturewas kept at 150°C and the object

OK 92.05 is a basic type electrodefor joining pure nickel in wroughtand cast forms. It can be used tojoin dissimilar metals such as nickelto steel, nickel to copper, copper tosteel and to surface steel.

OK 92.05 produces an austenit-ic weld metal and fulfils AWS/SFA 5.: ENi-1. A lab applicationwas carried out at the ESAB Pro-cess Centre in Gothenburg wherecopper was joined to steel. In thiscase, the copper was not pre-heatedbecause of its thickness, but, in cas-es where thicker or larger piecesare to be welded, pre-heating in ex-cess of 300°C is normal for copper.

was allowed to air-cool to roomtemperature.

The current was 55 amps forthe root run and 115 amps DC+for the fill.Root face 2 mm.Root opening 2 to 3 mm.Thickness of workpiece 5 mm.Joint geometry 70°.

OK 92 05 improved SMAW electrode for welding pure nickel

ESAB and GEISMAR co-operate successfully around Flash Butt Weldingof rail profiles and rail frogs


ESAB has put together a 44-pagecatalogue about submerged arcwelding. In addition to product in-formation, it also contains usefulinformation about the propertiesof different types of flux and theway these properties affect weldingresults. A Quick Selection Guideshows which flux and wire combi-nations correspond to different ENand AWS classifications, togetherwith an explanation of the waythese classifications should beinterpreted. There is a special sec-tion dealing with ESAB’s differentpackaging types, such as Big Barreland Big Bag, which offer bulk us-ers rational flux handling. The ad-vantages of the new Eurospool andthe Marathon Pac™ bulk pack arepresented in another chapter in thecatalogue.

Other valuable informationprovided in this new catalogue in-cludes the way productivity andwelding results are affected by thepolarity of the welding current andwhether one, two or three wiresshould be used or the addition ofmetal powder or cold wire. Thecatalogue also explains how to per-form a welding cost estimate, usinga calculation template.

The new SAW catalogue, whichis available in English, is recom-mended for everyone involved withsubmerged arc welding. It can beordered from ESAB’s Europeansales companies.

Welding defectsand the subse-quent repairand warrantycosts can bedue to negli-gence or alack ofknowledgewhen itcomes to thestorage and handling of con-sumables. ESAB is now publishinga revised version of its brochureentitled “Recommendations forthe storage, redrying and handlingof ESAB welding consumables”.

This brochure provides instruc-tions on the way stick electrodesand wires should be stored and

ESAB-Hancock has received amajor order from the Jos. L. Meyer-werft shipyard in Germany. Tocombat the competition fromAsiatic yards, Meyerwerft is ex-panding its production capacity byinvesting somewhere in the orderof DEM 200 million. Among otherthings, these investments include atotally new panel line with themost modern cutting technology.

Meyerwerft selected ESAB-Hancock for this order which isworth several million DEM. Itcomprises a 28 m wide TELEREXTXB 25000 panel machine, a

how they can be reconditioned af-ter incorrect storage. Suitableequipment for storing and drying,as well as different types of pack-aging which reduce the risk ofmoisture absorption, are also de-scribed.

A special section is devoted tothe handling of flux for submergedarc welding, together with the spe-cial requirements imposed on thestorage and handling of aluminiumwires and flux-cored wire. This newversion of “Recommendations forthe storage, redrying and handlingof ESAB welding consumables” iscurrently only available in Englishand can be ordered from yournearest ESAB office.

NUMOREX 6500 trimming ma-chine and the associated environ-mental equipment.

The automation level of thecutting unit and the specified pre-cision are the highest that are tech-nically feasible at the present time.The decisive factors when it cameto capturing this order wereESAB-Hancock’s technical system,combined with the high level of re-liability demonstrated by previouscutting equipment which ESAB-Hancock has supplied to this ship-yard.

New catalogue aboutSAW from ESAB

Storage and handling of consumables

World’s largest cutting machine to Meyerwerft inGermany


1. Gas-shielded metal arc brazingBrazing is a process for joining metallic materials withthe aid of a melted filler (solder), the melting tempera-ture of which lies below that of the parent metal. Theparent metal is wetted, without being melted.

In Gas-shielded Metal Arc (GMA) Brazing,copper-based alloys are often used as the filler, themelting temperature of which is below that of the steelto be joined. In an ideal situation, the parent metal isnot melted at the edges. Although the arc, which burnsunder a shielding gas atmosphere, is used to warm theparent metal and melt the filler, the process is muchmore like soldering. Suitable shielding gases for GMA-Brazing are inert gases like Argon but gas mixturesconsisting of Argon and small amounts of active gaseslike Oxygen are more common. Because of that theprocess is called GMA-Brazing including MIG- andMAG-Brazing.

2. Area of applicationSheet steel and steel sections are more and more fre-quently provided with protection from corrosion inthe form of an aluminium coating or layers of zinc, ap-plied either electrolytically or by hot-galvanising. Typ-ical areas of application are vehicle bodywork, compo-nents used in ventilation, cooling and air-conditioningequipment, household equipment, fire-resistant doors,roof and facade components in the building industryetc. Of course, many of these components have to bejoined.

3. GMA-brazing is given corrosion-protectionWhen welding galvanised structures, the evaporation ofthe zinc close to the seam causes a zone which is proneto corrosion because of the lack of a protective layer.Wires of the type EN 440 – G2Sil are also used to re-duce the tendency to produce pores, the weld metalfrom which offers no rust protection whatsoever. In thiscase the destroyed corrosion protection has to be re-stored subsequently at considerable expense, e.g. by re-galvanising. In contrast, copper wires are used in GMA-Brazing, which produce a corrosion-resistant solder.Copper is characterised by high solubility for zinc. Anexample of this is provided by the various brass alloys.The melting range of the CuSi3-alloy OK Autrod 19.30is approximately 910–1025°C, the melting point of zincis 419°C. During brazing, the liquid zinc remaining onthe surface of the sheet metal is included in the solderalloy, as a consequence of which a brass solder is pro-duced. This applies particularly to the transitionbetween the solder and zinc top layer adjacent to theseam. In the transverse micro-section illustrated (figure2) the bronze solder can be seen on the right side. Thelight yellow colouring indicates the low proportion of

ESAB pulsed gas-shielded metalarc brazing of surface-coatedsheetsby Dipl.-Ing. Hendrik Rohde, Jochen Katic and Dipl.-Ing. Rolf Paschold, ESAB GmbH, Solingen

Figure 1. Front and back of a GMA brazing seam on vehiclebody panels. A residual zinc coating is retained adjacent tothe seam and on the back.


zinc. This mainly involves �-brass. As the transitionfrom the solder to the remaining zinc layer is ap-proached, the proportion of dark coloured areas in-creases. The concentration of zinc in the solder is high-er here, ß-brass is present. The fluid transition from theCuSi-solder via a mixed layer consisting of brass to thezinc produces a sealed corrosion protection layer. Thisalso applies to the back of the weld on which a residuallayer of zinc is retained, even with thin sheet. TheESAB pulsed GMA-Brazing process makes subse-quent corrosion protection superfluous, digital regula-tion of the parameters reduces the evaporation of zincnext to the seam and from the back of the sheet.

4. Heat input and Zinc vapourThe boiling point of pure zinc is 907°C. Zinc begins toevaporate from this temperature onwards. As theamount of heat input into the galvanised sheet increas-es, a larger quantity of zinc evaporates. The zinc vapourcounteracts the transfer of droplets and deflects thedroplets. Targeted transfer of droplets into the moltenpool becomes impossible; the result is considerable for-mation of spatter and at the very least a seam with anunattractive appearance. Therefore, when GMA-Brazing the rule is: Only as much heat as necessary!

5. Pulsed GMA-brazing using the ESABAristo 2000-SystemA few users of the GMA-Brazing process have beenworking to date without a pulsed arc, which is only ad-

vantageous in the PG-Position. In these cases, the pro-cess takes place within the short arc mode. The shortcircuits associated with this between the wire electrodeand the parent metal lead to considerable spatter for-mation if the power source is not sufficiently well regu-lated.The heat input can only be controlled to an unsat-isfactory extent. In addition, the welder or “brazer”must adhere to a very constant contact tube distance aseven slight deviations lead immediately to considerablechanges in the parameters and consequently impair theprocess and the result. Handling is difficult and thewelder has the result “in his hands” in a very real sense.

The pulsed GMA-Brazing process with the ESABAristo 2000-System offers the best possible pre-conditions for a successful bond. As a consequence ofthe process, the flow of zinc vapour counteracts the arcpressure. This must be countered by using a slightlyforehand torch action and especially an extremely shortarc. This requirement makes very high demands on theequipment.

The digital Aristo 2000 achieves very high currentrise rates with very steep pulse signal edges in order toenable small droplets to be transferred to the moltenpool in a targeted way with short pulse current times.The digital regulation system has to work extremelyquickly and precisely to achieve this – a requirementwhich the ESAB Aristo 2000-System fulfils exception-ally well.

Successful pulsed GMA-Brazing also makes highdemands on the wire feed unit because the process doesnot tolerate even slight changes in the rate at which thewire is fed.The regulated ESAB wire feed system keepsthe speed required at a constant level regardless of ex-ternal disruptions.

With the ESAB Aristo 2000-System, handlingpulsed GMA-Brazing is less “the driving force for theweld” because the tolerance is much greater in sofar asthe distance away of the contact tube is concerned. Theapplication of heat is reduced; where very thin body-work sheet is concerned, there is less risk of the seamcollapsing.Taken as a whole, the ESAB technology pro-vides a better result in sofar as quality assurance, corro-sion protection and the appearance of the seam areconcerned.

The digital Aristo 2000 system used offers both theconvenience of a synergy setting and the possibility ofoptimising all the parameters relevant to the process in-dividually. The values produced can be filed on a PC-

Figure 2. Transition from copper braze to galvanized basematerial. The braze and the zinc coating mix to form brass.

Figure 3. Transverse sectionthrough GMA -brazing seamon a body panel (s = 0.8 mm).Location of section: undersideof panel. A residual zinc coat-ing is retained.

Steel sheet

Steel

Zink coating

�-Brass �-Brass (light)


Wire Cu Si Mn Meltingrange °C

OK Autrod 19.30 Basis 3.0 1.0 910-1025

Figure 4. ESAB Aristo 2000 – LUD 320.

memory card and loaded into the system again whenrequired. If the arc power is to be adjustable continu-ously over a certain range, the user can program hisown characteristic curves for synergy without enteringinto the system. In this way, he can combine the individ-uality of his optimised setting with the convenience of asynergy. Using this PC-memory card, we can also findparameters for you at our premises, optimise and storethem. Then you simply load these data into your LUDand start.

6. Wire for GMA-brazingA number of different copper wires can be used forGMA-Brazing. Normally, the 3% Si-alloy OK Autrod19.30 (DIN 1733: SG-CuSi3) is used:

The wire diameter 1.0 mm is the main one used.Delivery is usually on 15 kg basket spools. For mecha-nized and fully automated systems OK Autrod 19.30Ø1.0 mm is also available in the ESAB MARATHONPACTM Octagonal.

OK Autrod 19.30 is particularly suitable for GMA-Brazing. Hardly any spatter is produced when com-bined with the ESAB Aristo 2000-System. No pores orcracking of the solder was found in the brazing speci-mens investigated. No scales are formed and there isonly a very thin layer of slag on the surface. The ESABOK Autrod 19.30 provides very good wetting and gapbridging (figure 5). As a consequence of capillary ac-tion, the solder flows into the air gap of overlap jointswell. The relatively soft solder makes it easy to removethe weld reinforcement, in so far as this is at all neces-sary to produce a flat seam. When removing it, the zinclayer alongside the seam is damaged far less than is thecase with hard weld metal.

7. Shielding gases for GMA-brazingPure argon is frequently used in practice for GMA-Brazing. However, gases with a proportion of active gasare also suitable for GMA-Brazing, e.g. gases EN 439-M12 with CO2-proportions of 1–3%. More recent in-vestigations at ESAB have shown that the use of anM13 shielding gas complying with EN 439 (Ar+1% O2)is advantageous. The surface tension of the molten poolis reduced, as a consequence of which the flow and wet-ting characteristics are improved significantly. At thesame time the stability of the arc improves. No scalesare formed in the seam and it has an excellent appear-ance. However, the use of shielding gases containingproportions of active gas raises a number of questions.Copper forms copper oxide (Cu2O) when combinedwith dissolved oxygen. Cu2O is deposited at the particleboundaries which can tear open during cold forming. Ingeneral, a very brittle microstructure is produced. As aconsequence of the embrittling effect of the copper ox-ide, only well de-oxidised types of copper are deemed

Figure 5. Transverse section through ESBA GMA-brazedjoints on vehicle body panels (s = 0.8 mm) with differentgap widths. The braze flows deep into the gap.

Figure 6. Dark-field image of the CuSi3 braze when usingan M13 protective gas. The few eutectic precipitationscontain only small fractions of Cu2O.

Cuprous oxide Cu2O


suitable for welding. More precise investigations wereundertaken at ESAB to establish whether using shield-ing gases with an active gas content has a disadvanta-geous effect on brazed seams. It became apparent dur-ing the latte that only extremely small proportions ofcopper oxide can be detected in the solder and thatthese are only present in a small number of zones con-taining eutectic separations. The silicon present in OKAutrod 19.30 has a deoxidising effect and keeps theCu2O-proportions very low.

As small proportions of Cu2O are only present inrestricted areas and no marked particle boundary filmswere found anywhere, no embrittling effect is to be ex-pected. Consequently, there are no objections to smallproportions of active gas in the shielding gas. This wasalso supported by the investigations undertaken onstrength.

8. Strength of the brazed jointsPulsed GMA-brazed joints were produced on an over-lap joint in electro-galvanised sheet metal bodywork0.8 mm thick. OK Autrod 19.30 ∆1.0 under shielding gasM13 with 1% O2 and the ESAB Aristo 2000-Systemwere used. Then flat tensile test specimens were takenand tested:

The position of the fracture in the tensile test spec-imen was always in the unaffected parent metal! There-fore the ESAB GMA-brazed joints fulfil the demandsmade of the joint completely.

9. Suggestions for practical useThe optimum parameters are more difficult to set forGMA-Brazing than for MIG/MAG-welding. The thick-ness and position of the zinc layer, in particular, play avery large part. Setting all the pulse parameters individ-ually is indispensable for the best possible result.

Torch position

In GMA-Brazing, the torch position can have a consid-erable influence on the formation of the seam and theintroduction of heat into the parent metal, as inMIG/MAG-welding. Less heat is brought into the gal-vanised parent material if the torch is in a forehand po-sition. It causes a smaller quantity of zinc to evaporateand the degree to which droplet transfer impaired issignificantly lower. With the torch held in a forehandposition, the brazed seam is flatter and somewhat wid-er, but more importantly, there is less spatter. The un-avoidable amounts of spatter, which occur at the start

About the authors

Hendrik Rohde graduated in 1991 as a mechanical andwelding engineer from the Technical University ofMagdeburg and joined ESAB Germany in the same year.In 1995, he became a European Welding Engineer. He isnow product manager for arc welding products withGMAW as the main field and he also specialises inmodifications for the use of welding machines withmechanised equipment.

Jochen Katic is an EWS and works as a demo-welder formechanised welding processes. He joined ESAB GmbHSolingen in 1990. Mr. Katic is also a specialist in weldingwith flux-cored wires and he is often involved in researchand development projects for customer applications inautomatic and robotic welding.

Rolf Paschold, product manager at ESAB GmbHSolingen (Germany), graduated in 1990 as a mechanicaland welding engineer. He joined ESAB in 1991 and is thesales support manager for welding consumables. MrPaschold has always shown a special interest in tailor-made process applications developed together with thecustomer.

of the process because the evaporation of the zinc isstronger, land before the torch and are reliably meltedagain.

Molten pool

GMA-Brazing can be done with the molten pool run-ning slightly ahead. This is a little strange to theMIG/MAG-welder at first because he usually has to en-sure the avoidance of bonding errors and reliable pen-etration. However, deep penetration is undesirable inGMA-Brazing; it is only necessary to ensure good wet-ting.

10. Conclusion

ESAB provides all the pre-conditions for successfulpulsed GMA-Brazing. The Aristo 2000-System makesdigitally regulated power sources and wire feed devicesavailable which fulfil the high demands of the pulsedGMA-Brazing process in the best possible way. Com-bined with the wire electrode OK Autrod 19.30, brazedjoints are produced which demonstrate the best qualityand excellent mechanical quality values.

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The use of rutile cored wires forwelding high strength steel incrane fabrication by Ben Altemühl, ESAB B.V., Utrecht, The Netherlands

High strength steels are increasingly applied in crane fabrication, withthe aim to obtain weight savings or a higher lifting capacity. Simultane-ously, cored wire welding is becoming more popular. This has to dowith the high quality demands cranes are subjected to for security reasons, but also with the higher welding productivity cored wires offer.

AWS A5.29-98 EN 12535-00 Approvals

OK Tubrod 15.07 E101T1-K7M H4 T 62 4 Mn2Ni P M 2 H5 –OK Tubrod 15.09 E111T1-GMH4 T 69 4 Z P M 2 H5 ABS*, LR*

On the European welding consumable market, theavailability of cored wires for high strength steel hasbeen limited to mainly metal-cored and basic types. Re-cently, however, ESAB has introduced two rutile typeswith a minimum yield strength of 620 and 700 MPaunder the product names OK Tubrod 15.07 and OK Tub-rod 15.09 respectively.

The wires are characterised by high welding pro-ductivity, good mechanical properties, a very low weldmetal hydrogen content, and above all, excellent weld-ability.

ESAB developed these wires at the request of sev-eral European crane fabricators, among which theDutch company Huisman-Itrec.They tested the OK Tub-rod 15.09 for welding Weldox 700 and have gained pro-duction experience in a number of projects.

OK Tubrod 15.07 is still in its testing stage. At thismoment, it is being tested for the mechanised weldingof pipelines in X80.

This article will introduce the new rutile coredwires for high strength steel, while describing the expe-riences of Huisman-Itrec with the OK Tubrod 15.09.

Huisman-ItrecHuisman-Itrec B.V. in Rotterdam, is the result of a mer-ger in 1981 between the crane fabricator Huisman andthe engineering bureau Itrec. Their most important ac-tivity is the construction of cranes and other liftingequipment for the offshore industry, the dock industry,civil works and shipbuilding. With design facilities forengineering, hydraulic and electric propulsion systems,

and for software, the company delivers client specifiedinstallations. Huisman-Itrec specialise in systems thatare not available on the market as standard products.Examples are cranes for deep-water applications, andship motion compensation systems. Other productsbuilt by Huisman-Itrec are floating sheerlegs, self pro-pelled heavy transporters, equipment for installingpipelines on the seabed, drilling equipment, and evenamusement park attractions. These products are deliv-ered to clients all over the world.

The company constructs according to the require-ments of the leading approval societies in this branch ofindustry (e.g. Lloyds), and execute a high quality stan-dard. When not building on site, products are testedwith in-house facilities, before delivery.

Table 1. AWS and ENclassifications and approvals.*= limited approval.


%C %Si %Mn %Ni %Mo %P %S

OK 15.07 0.04-0.07 0.30-0.50 1.45-1.75 2.30-2.70 – <0.020 <0.020OK 15.09 0.04-0.09 0.30-0.50 0.95-1.35 2.50-3.10 0.25-0.35 <0.015 <0.015

Rp0.2 Rm A5d ISO-V(MPa) (MPa) (%) (J at –40ºC)

OK 15.07 >620 700-830 >18 >47 (>27 at –50ºC)OK 15.09 >690 770-900 >16 >41

OK Tubrod 15.07 and 15.09Both types are all-positional rutile cored wires withAWS and EN classifications according to table 1. Thestrength properties are tuned for high strength steelwith a minimum yield strength of 620 and 700 MPa,with good CVN toughness at –40ºC. Table 2 gives theall-weld metal chemical composition and mechanicalproperties.

The wires are developed for all-positional weldingunder 80%Ar/20%CO2 shielding gas, falling within EN439 class M21. Vertical down welding, however, is notrecommended because of the high risk of cracking inthe first thin layer; especially in fabrications with a highrestraint.

It concerns butt-closed cored wires with a filling de-gree of approximately 18%. The slag is fast freezing tosupport the weld pool during positional welding. Thearc action is spray-arc at all welding currents, and theweldability is excellent. Another advantage is that, withthe same wire size, a uniform parameter setting can beused when components have to be welded in severalpositions.

The high productivity, compared to solid wires andbasic cored wires, becomes apparent in positional weld-ing (PC, PF and PE). Vertically-up welding with a dep-osition rate of 3kg/h, for instance, is attainable.

The weld metal hydrogen content falls within ClassH5 of EN785 for the operating envelope of parametersand corresponding stick-out lengths, which is excep-tional for rutile consumables. This is of great impor-

tance for the welding of high strength steels. Normally,the weld metal has a higher Carbon Equivalent thanthe high strength parent metal, and therefore it willundergo the austenite-ferrite transition later. For thisreason, hydrogen in the weld metal will not be able todiffuse to the heat affected zone and remain in the weldmetal.Add this to the limited heat input, needed to givethe weld metal sufficient strength properties, and all in-gredients are present to cause hydrogen induced crack-ing. Low-hydrogen weld metal is therefore crucial forsuccessful crack-free welding. This is also reflected bythe preheating recommendations for Weldox 700,which are based on H5 class filler materials (Table 3).

The wires are not recommended for constructionsthat are submitted to a stress relief treatment, whichwould result in partial loss of toughness properties. Inthese cases, the use of a basic cored wire is advised.

Experiences with OK Tubrod 15.09 in cranefabricationThe introduction of OK Tubrod 15.09 at Huisman-Itrecis part of a general transition from solid to cored wirewelding, carried through over the past years by thewelding department with the aim to improve the all-over welding productivity. An additional advantage, es-pecially with rutile cored wires, is that also temporarywelders master the required skills relatively quickly,which enhances the flexibility required by production.

At this moment, over 85% of all weld metal is depos-ited with metal cored or rutile cored wires, whichbrought along a substantial increase in productivity.It concerns mainly manual welding, but the welding de-partment is investigating the possibilities of light me-chanisation.All welders are certified up to H-L045 (6G).

Figure 2. Vertically-up welding of a crane beam in Weldox700.Figure 1.

Vertically-up weldingof a crane beam inWeldox 700.

Table 2. All weld metalchemicalcompositionand mechanicalproperties.


Combined thickness (mm)t1+t2+t3= 10 20 30 40 50 60 70 80 90 100 110 120 130

Table 3. Preheatingrecommendations forWeldox 700 based on amaximum heat input of1.7kJ/mm and low-hydrogen weld metal(EN 785 class H5).

Table 4. Mechanicalweld metal propertiesat a correct heat inputand a too high heatinput. V-joint/ platethickness 30mm,combined thickness60mm/ Weldox 700Heat no. 366631/position PF. WF = Weld Face, FL = Fusion Line, WR = Weld Root, FR = Fusion Line Root.

Huisman-Itrec increasingly applies Weldox 700high strength steel for the construction of lifting equip-ment. The components to be welded, such as cranebeams, masts and pedestal parts, are too large to beturned, making positional welding unavoidable. Untilrecently, the Weldox 700 was welded with a combina-tion of coated electrodes and solid wire, but also herethe company wanted to change over to 100% coredwire welding. That is why they requested ESAB to de-velop such a wire, which received a positive reply, alsomotivated from an international context.

After the development of the wire, Huisman-Itrecsubmitted the first test spools to a rough test to verifythe suitability for welding Weldox 700. It concerned aV-joint in thick plate, welded in PF position withoutpreheating and without controlling the interpass temper-ature.The strength properties of the joint were measuredby tensile tests with transverse and longitudinal test bars.Cross weld, a tensile strength of 769MPa was obtained,with the rupture in the parent metal. In the longitudinaldirection, the yield strength was too low (668MPa)whereas a tensile strength of 754MPa was satisfactory.

Figure 3. Crane pedestal part.

Figure 4. Vertically-up welding of a pedestal part.

Correct heat input 1.2-1.4KJ/mm/Tp 80ºC/Ti 170ºC

Tensile test Rm (MPa) Re (MPa) A (%)848 825 15.6

CVN at –40ºC (Av.3) WF FL FL+2mm FL+5mm WR FR FR+2mm54 54 161 161 33 39 122

Hardness HV10 (Av.3) Weldox 700 WBZ Las WBZ Weldox 700Root 273 434 297 417 279Center weld 276 343 259 331 286

Bend test Magnaflux UltrasonicOK no indications no indications

High heat input 1.7-2.0 KJ/mm/Tp 80ºC/Ti 190ºC

Tensile test Rm (MPa) Re (MPa) A (%)841 780 15

CVN at –40ºC (Av.3) WF FL FL+2mm FL+5mm WR FR FR+2mm54 102 168 123 31 30 135

Hardness HV10 (Av.3) Weldox 700 WBZ Las WBZ Weldox 700Root 266 397 290 395 282Center weld 266 343 289 346 861

Bend test Magnaflux UltrasonicOK no indications no indications

Rm Re A5 CVN (MPa) (MPa) (%) –40ºC (J)

Weldox 700 780-930 >700 >14 >27Heat nr. 366631 826 759 15 158(Av.3)

100ºC 150ºC75ºCWELDOX 700


The CVN toughness (Av. 3) was 53J at–40ºC for the weld and 42J for the root(welded on ceramic strip).The results ofthe side bend tests were good. Subse-quent ultrasone and magnaflux testingproved that the weld was free of defectsand, more importantly, cracks.

WPS’esOn the basis of these results, the weld-ing department of Huisman-Itrec de-cided to continue the investigation,aiming at the establishing of suitablewelding procedure specifications(WPS) for Weldox 700. In addition, thecompany wanted to obtain a Lloydsyard approval for a project with a CVNrequirement of 27J at –40ºC, awaitingthe general Lloyds approval ESABhad requested.

Table 3 gives the preheat recom-mendations for Weldox 700, based on aweld metal hydrogen content of max.5ml/100g deposited weld metal and amaximum heat input of 1.7kJ/mm. Tounderstand the effect of the heat inputon the mechanical properties, testplates were welded (800�30�30mm)at a correct heat input (1.2-1.4kJ/mm)and at higher heat input (1.7–2.0kJ/mm). Table 4 summarises the re-sults.

The strength requirements of Wel-dox 700 (Table 5) were met, as well asthe maximum hardness requirement of425HV10. The same is valid for theCVN toughness of the weld; even forthe root.

On the basis of these results,Huisman-Itrec was granted the local approval theyneeded for OK Tubrod 15.09, valid for one specific prod-uct and one batch. Figure 5 shows a WPS for the posi-tion PF that Huisman-Itrec developed subsequently.

In a later stage, ESAB obtained the general Lloydsapproval; be it with a limitation. For this class of con-sumables, Lloyds has a CVN demand of 69J at –40ºC.For rutile consumables, this is too high, however.That iswhy the approval is limited to projects with CVN re-quirements of 42J at –40ºC or lower, which is sufficientfor many applications.

Fabrication experienceHuisman-Itrec applies OK Tubrod 15.09 for welding inPF position. For downhand work, they kept on using ametal-cored type. After successful use on a smaller pro-ject, OK Tubrod 15.09 was utilised for a bigger project,the fabrication of a series of cranes for Mammoet B.V.The figures 1 to 4 show the application of the wire.

It is applied successfully for the vertically-up weldingof crane beams, pedestal parts and other crane compo-

nents. The welders are very pleased with the new con-sumable and also temporary workers learn to use it with-in an acceptable period of time. Essential for weldingWeldox 700 is that the low heat input, needed to obtainsufficient strength and toughness, can be maintainedwell, also in PF position. This is more difficult with solidwire, basic, or metal-cored wires, because these are weld-ed close to the short arc mode.The success also becomesapparent from the 100% ultrasonic and magnaflux NDTthat was performed. The defect rate was below 0.5%.

About the author

Ben Altemühl, BSc, welding engineer, joined ESAB in1990 as sales promotion manager for FILARC Welding Industries in the Netherlands. Since 1999, he has been responsible for the sales promotion of all cored-wireproducts within ESAB Europe’s Business Area Consum-ables.


The new ESAB EcoMig weldingwire adopted by Fai Komatsu Industries for welding its earth-moving equipment.

by Ferruccio Mariani, ESAB Italy

High performance, reliable quality and product ecology are the main reasons for the choice of ESAB OK Autrod 12.50 Eco Mig wire. At FKI, Fai Komatsu Industries, highly-developed welding systems and processesare used for welding specialized products which are aimed primarily at demanding markets in industrialized countries.

Robotic cells with fully-automated loading and unload-ing systems, combined with the latest generation ofhigh-speed welding processes, all complying with envi-ronmental requirements.

In just the same way that a formula 1 engine has tobe filled with a sophisticated fuel in order fully to devel-op its power, FKI has adopted a welding wire whichcomplies with the demanding requirements imposed byits welding equipment and processes to provide out-standing performance.

ESAB OK Autrod 12.50 EcoMig in the octagonalMarathon Pac not only comes up to all the company’sexpectations, it also produces other additional advan-tages, as we will see in the following interview.

FKIFKI S.p.A. in Este (Padua, Italy) is one of the four pro-duction units of the Komatsu Group in Europe and spe-cializes in the so-called “utility range”.

The company was set up in 1963 with the nameFAI, Fabbrica Attrezzature Industriali (IndustrialEquipment Factory).

Its initial operations focused on equipping tractorswith some added components in order to make themmore versatile and suitable for many different opera-tions.This is how the so-called “terna” was born, a namewhich recalls its three functions: the tractor itself, thefront shovel and the rear excavator. During the devel-opment of the building trade, changes in market de-


mand led the “terna” to become fully independentequipment, retaining only the functions of digging andloading but keeping its name at the same time.

Over the years, other products were added to the“terna” and FAI continued to expand until about 12years ago, when it came in contact with Japanese Ko-matsu and set up a joint venture for the production of arange of mini-excavators, a product which had not yetbeen introduced in Europe. The relationship developedand was consolidated about four years ago with thebirth of FKI, FAI KOMATSU INDUSTRIES S.p.A., inwhich 100% of the shares are owned by Komatsu. Now-adays, FKI has almost 900 employees.

“Turnover in 1999 was USD 260 million, this year itwill be about 325. During the last three years, we havemore than doubled our turnover,” says Claudio Gallana,production manager, with justifiable pride in his voice

“This is thanks to synergies with the Komatsu Groupand particularly to favourable trends on the market.”

FKI’s market operations focus on five productlines: firstly excavators, secondly the stiff “terna” seriesthat is expanding rapidly thanks to new markets, likethe USA, thirdly the line of articulated “ternas”, similarto the previous one but with central articulation that al-lows the machine to operate in narrow environmentsand more uncomfortable situations. They are followedby the line of so-called “skid steer loaders”, small load-ing machines. This is an important product for FKI andit is experiencing a particular period of market growth.Last but not least comes the line of compact excavators,also called midi-excavators.

FKI constitutes the focal point of the utility divisionwhich is experiencing powerful expansion in the Ko-matsu Group, as it is the only manufacturer of this


range of products for the European market. Utility isthe series of relatively small machines which are used inthe building trades for repair and maintenance work,like roads, pavements and so on. The market is experi-encing very favourable trends, mainly in industrializedcountries where the major infrastructure, such as roads,bridges and viaducts, has already been constructed butwhere there is a great deal of work to be done in cities,or historical centres, or constructing new apartmentblocks, where machines of this kind play a key role. Inspite of the relatively high investment cost, they are amore efficient alternative in all the above-mentionedcountries where the labour costs are really high.

We asked Mr. Gallana for some information aboutmarket position, objectives and strategies.

“On a worldwide scale,” he replies, “when it comesto the global market and product dimensions, it would betrue to say that Komatsu and Caterpillar are always com-peting for first place. Afterwards,” he continues smilingand looking at the ground “there are some others... Any-way, not all the players are comparable in terms of prod-uct range and type. As far as our Italian production isconcerned, it has to be said that we have an importantpresence on the Italian market; in fact, for some productsit accounts for more than 30–35%. For instance, themini-excavator made its appearance on the Italian mar-ket together with us. We are now also supplying theAmerican market, mainly with two product lines: “ter-nas” and skid steer loaders.

“At this very moment, one extremely important ob-jective is to keep our market shares at a high level andthis isn’t so easy because the market is growing at a real-ly fast rate, even faster when we add the further positivefeedback from group synergies.

“One of the main difficulties in our area is findingskilled workers. I want to give you an example; it is stilleasy enough to find young technicians if you offer them

the chance to operate a welding robot, but, when youlook for a welder who is able to handle a welding torch,that’s much harder. That’s why we have pushed the accel-erator on robotic welding, also taking account of thehigher productivity and the profit produced by the lowercost of robotic technology nowadays. We definitely needto stay on the road to productivity. At the same time, wemust take care of the balance between our growth, whichis forecast to remain good over the next few years, andthe related costs, because the favourable trend on themarket cannot last for ever.”

Importance of weldingAs far as production is concerned, the five product linesare produced on three assembly lines, so there is a prod-uct mix on some lines. The majority of components arewelded inside the factory – this particularly involves themain structures of the machine, while small or minorcomponents and sub-assemblies with less rigorous re-quirements are supplied by outside subcontractors.

Basically the production cycle is as follows: the com-ponents are pre-assembled using special equipment,which is very flexible, the result of Italo-Japanese jointdesign. They are then taken to the robotic cells wherethe welding operation is performed. Robotic welding ac-counts for 80–90% of the total weld, but some weldingstill has to be done manually for many reasons, such asdifficult access to the welding position and so on. Sothere is a final phase in which the small percentage ofwelding that is left is completed manually.

The welding operation employs about 10–15% ofthe total work force directly or indirectly. In terms ofwelding time in the production cycle, the situation is nothomogeneous, it varies because, for some machines, allthe components are welded inside the factory. In thiscase, welding takes 30–35% of the total cycle time. Forother types of machine, only the main components are


welded inside, while minor components are subcon-tracted to outside suppliers. Taking account of this var-iability, it would be true to say that an average of 60%of the structures are welded inside.

Anyone used to visiting welding departments atmechanical industries would expect to find the well-known “atmosphere” at FKI as well: arcs crackling andflashing, the emission of fumes in the environment,piles of welded and unwelded components close towelding stations, noise... well you could not possibly bemore mistaken! With the maximum respect for sacredthings, when you enter the welding hall at FKI, you feelas though you are entering a cathedral. This is the per-fect definition: space and airiness, a sober atmosphere,cleanliness, a lack of noise and arcs flashing. What im-presses the visitor instead is the sight, inside the hall, oftwo rows of cubic constructions, each about ten metreswide, surrounded by rail tracks: they are the roboticcells. Inside, there are the welding robots with the relat-ed positioning devices. Every cell is equipped with avery effective system of electrostatic filters which trapthe last molecule of particles and fumes developed bywelding. Electric arcs, radiation, heat, fumes and noiseare therefore restricted inside the cells. This is a 93-metre line made up of six - it will be eight by the end ofthe year – robotic cells, supplied by a trolley system forloading and unloading the components in a fully auto-mated and randomized manner.

Each robot is programmed in such a way that it canrecognize every component and carry out the relatedwelding programme. In other words, the first assemblyon the waiting list goes to the first cell where the previ-ous welding programme has been completed. Thissystem allows maximum flexibility in the production cy-cle and high efficiency, cutting all the waiting timesfrom the different preparation times for the differentcomponents.

The welding process is the high-speed T.I.M.E. pro-cess, which offers very high productivity in welding. Ob-viously, the requirements imposed on the welding wireare really demanding: over 400 amp current (the diam-eter size which is used everywhere is 1.20mm), over 20m/min wire speed, a 20-metre liner guiding the wirethrough the chain system of the three-axis cartesian ro-bot gantry up to the welding head. Last but not least, af-ter such a long journey, the wire ends up with a verylong stick-out that has to be absolutely straight!

“High quality together with consumable reliabilityare basic requirements,” Mr. Gallana stresses. “Weldingis a complex problem, especially robotic welding, be-cause it is affected by plant-related phenomena as well asby the consistency of the consumables – the shielding gasand wire, particularly in such a complicated process aswe have.The first and most important requirement for usis the consistency. Another basic requirement is the ser-vice; this involves a continuous search for improvements,as well as the solution to specific problems. In otherwords, the ability to conduct new tests, find fast solutionsand react quickly – to be innovative. As far as I’m con-cerned, ESAB fulfils these requirements.”

From OK Autrod 12.51 Marathon to OK Autrod 12.50 EcoMig in the octagonalMarathon PacWe contacted Giampaolo Bellucco, the person respon-sible for auxiliary materials. “Since we introduced ro-botization, the need to use large wire packaging has aris-en,” he explains.

“As a first step, we conducted some trials with 90 kgbobbins, but the real solution came when ESAB sup-plied us with its OK Autrod 12.51 wire in the Marathondrums. Since the beginning, it has come off best com-pared with all its competitors. We started using it and wethen continued for years, but...good, better, best, never letit rest! Recently, we performed a number of rigorouslarge-scale tests on products and suppliers and this tookus a further step forward.”

“Once more, ESAB emerged as the winner with itsnew ecological wire OK Autrod 12.50 EcoMig, which wehave now definitively adopted. All the other competitorsfailed miserably because the actual results did not comeup to the promises.”

Silvano Crescente, the person responsible for FMSplant, joins in. “Since I started using this new wire, I haveencountered far fewer problems on this plant. This isvery sophisticated equipment, the wire mustn’t createproblems, we use the T.I.M.E process, the programmingis fairly complicated and it does not forgive mistakeswith the welding wire. Constant, regular feed is an essen-tial factor. We have six robots, since the first test we start-ed with all of them, I’m talking about 35–37 pieces a day,two hours of arc time per piece on average, you can real-ly see if the wire can take the punishment. As a matter of


fact, the evaluation comes out completely in favour ofESAB OK Autrod 12.50 EcoMig compared with all thewires tested.

“Every stoppage costs money,” continues Mr Cres-cente “because a package of unreliable wire results in aone-hour stop, including checks and replacement. A reli-able wire like this generates nice savings!”

“We haven’t yet quantified the accuracy,” Mr. Belluc-co adds, “but we have noted a number of additional ad-vantages: lower torch and liner cleaning frequency, lessspatter, longer service life for contact tips, generallyspeaking I have noted a sharp reduction in all the com-ponents that are subject to wear, which means that lesstime needs to be spent on maintenance as well. Now Imust say something about fume reduction, that’s real evidence!”

Environmental considerations At this point, we allow ourselves the luxury – meta-phorically speaking – of interrupting Mr. Bellucco forjust a short digression. FKI’s industrial complex is locat-ed in Este, at the foot of the Euganei Hills, a well-known area which has become rich and famous thanksto its thermal springs and waters, a place where the en-vironment creates well-being and health. It could be acoincidence, but it is noticeable that, as far as we know,FKI is the first company, or at least one of the first, inthe metal-mechanical field in Italy to have applied forenvironmental certification according to ISO 14.000and the company will shortly be receiving it.

“ISO 14.000,” explains Mr. Bellucco “ is the normthat governs the environmental impact of operationsfrom every angle. We have made a clear-cut, intentional,evaluated and planned choice in this area, even if I haveto admit that complying with this standard is far moredemanding compared with what we needed to do yearsago to obtain the quality certificate according to ISO9000. How to get rid of waste, how to control air pollu-tion, the products and their handling, the contact of dif-ferent products with the employees and the impact of ourproducts on the environment and so on...it’s a really de-manding task.

“For many years, we developed our control systemand managed our purification systems, but another stepforward now has to be made. It relates first and foremostto people’s cultural side. The working environment ispart of our life, I mean “our” in the widest sense of theword on a world scale. Everybody must be prepared torespect the standards that eventually generate commonwelfare. In this respect, our personnel are very positiveand co-operative. Last but not least, we must rememberthat a comfortable working environment is an incentivefor higher efficiency.

“An excellent illustration was recently given here byESAB’s Autrod OK 12.50 EcoMig wire, when the weld-ers realized that it developed far fewer fumes.We are nat-urally taking advantage of this in robotic welding be-cause it reduces the frequency with which the electrostat-ic filters need to be cleaned, which has an obvious advan-

tage when it comes to productivity, but robotic welding isdone inside the cells while the operators are outside sothat they are not in direct contact with the arc and fumes.However, we also have semi-automatic welding sites.There are about 30 of them at which minor componentsor sub-assemblies are welded. Even if there is a fume extraction system, the fumes developed by welding arestill immediately visible and in direct contact with thewelder’s environment.”

“In the past, in order to obtain higher productivity bymeans of higher duty cycles, we made many attempts tomove from 15 kg reels to higher weight packages likeOK Autrod 12.51 Marathon, in order to reduce the stop-pages caused by changing the reel every 15 kg. Of course,everybody knows that this kind of stoppage is welcomedby welders as it often gives them an opportunity to havea short break during work.”

“Well, as soon as we asked the welders to test the newecological non-copper-coated OK Autrod 12.50 wire inthe octaconal Marathon Pac we were surprised to findthat they fell in love with it. They have not only acceptedit, they have even approved it through their trade unionrepresentatives. Nowadays, it is the only wire they want.They have realized that being at the forefront when aninnovation is introduced is useful for them and not justfor the company. All of this is mainly due to the sharp reduction in fumes.”

“An ecological product like this makes our life easi-er, even when it comes to the acquisition of ISO 14.000.

“By the way, the new octagonal Marathon Pac is alsoan advantage. When it is empty, the cardboard can beeasily squashed and stacked on pallets, you can pile upmany of them in a very small space and, finally, manag-ing rejects is less demanding from a logistical point ofview.”

ESAB’s role We ask Mr. Bellucco to formulate a final opinion ofESAB. “When it comes to the product itself, I think I’vealready said everything. When it comes to supplier qual-ity, I would put it this way.

“Each company’s name is associated with an image,but, when you analyse the facts in depth, the ‘real’ imagedoes not always correspond to the ‘virtual’ one. InESAB’s case, I must say that the image associated with itsname is synonymous with the actual, verified truth – reliability. At least as far as we are concerned.”

“Not because there has never been a problem, butbecause, whenever problems have occurred, ESAB hasalways been able to accept and resolve them, giving usthe necessary support. I have had the chance to verify theservice, reliability and consistency. I find that ESAB is aproblem-solving supplier which is available and ready towork together. It makes me feel secure. It’s more thanenough!”

Mr. Bellucco’s conclusion is very gratifying for acompany like ESAB that has always wanted to work to-gether as a partner alongside its customers and to pur-sue objectives of common interest.


Welding hydraulic cylinders using OK Tubrod 14.11 and theMAG and MAG-tandem processby Dipl. Ing. Klaus Blome, ESAB GmbH, Solingen, Germany

Hydraulic cylinders are a vital part of modern industrial machinery.All the operating movements of large equipment such as earth-movers and road-building machines can be performed with a veryhigh level of accuracy and dynamics, especially when combinedwith electronic controls.

An hydraulic excavator (Figure 1) performs its opera-tional movements via hydraulically-activated cylinders.The boom is lifted by two hydraulic cylinders (Figure2), while the jib and the bucket are each moved by onehydraulic cylinder (Figure 3). Depending on the size ofthe machine, the design pressure of the cylinders isbetween 160 and 320 bar. Pressure peaks which areseveral times the design pressure may occur during op-eration when the static load (load in the bucket, intrin-sic weight) and the dynamic forces (moving the excava-tor, loading or unloading process) are superimposed.The design and in particular the production and qualityassurance of these components is therefore extremelyimportant.

Connecting the cylinder head and base to the guidetube (Figure 6) imposes rigorous demands on the qual-ity and reliability of the welding process that is used.

In most cases, the circumferential welds take theform of U-welds. The centring, which is machine turnedso that it can be assembled as a perfect fit, serves asbacking for the root pass (Figure 7).

As the tube is machine turned to a preset fit dimen-sion (e.g. H8) after welding to guide the piston, mini-mum penetration is specified for the root pass (depend-ing on the design, approx. 1.5/3 mm). During this pro-cess, the centring lip must be melted so that a defect-freesurface is produced when it has been machine turned.

A number of different welding methods are used tomeet these quality requirements, while increasing pro-ductivity at the same time. They include:• MAG or MAG pulse with solid wire and various

shielding gas mixtures to improve penetration char-acteristics, especially in the root

• Friction welding and flash butt welding• MAG double-wire or MAG tandem welding

If reliable, deep penetration and increased produc-tivity are required as a result of higher welding speeds

and/or process reliability, it is possible to utilise the spe-cific characteristics of OK Tubrod 14.11, metal-coredwire. The stable, wide arc guarantees reliable penetra-tion and uniform seam quality. The special striking andfeeding characteristics of this flux-cored wire, which hasbeen optimised for automated processes, make an al-most defect-free process cycle possible, even in con-junction with high welding parameters and when usedfor long periods.

Figure 1. Hydraulic excavator.

Figure 2. Lifting hydraulicsfor the boom.


OK Tubrod 14.11 has already shown itself to be ex-tremely effective when manufacturing hydraulic cylin-ders for excavators and other road-construction ma-chinery. U-welds, as illustrated in Figure 7, are weldedin four passes using OK Tubrod 14.11 � 1.4 mm. This involves the use of either conventional MAG tech-niques (Table 1) or the MAG tandem method (Table 2).

In comparison with the MAG tandem method,which was used in the past with 2�1.0 mm solid wire,the welding speeds achieved in this case in productionconditions with OK Tubrod 14.11 � 1.4 mm were al-most able to match those of classical MAG weldingwith a wire electrode. It was even possible to increaseproductivity because the quality of the welded jointswas significantly better and more reliable.

To obtain a further increase in production, it is pos-sible to weld the intermediate layer of relatively largehydraulic cylinders using the MAG tandem method and2�OK Tubrod 14.11 � 1.4 mm. The reliability of theprocess is so high, as a result of the high stability of thearc and the fine feeding characteristics of the flux-coredwire, that the second flux-cored wire (slave) can be ap-plied without interrupting the welding process. At thesame time, the welding speed is naturally increased inorder to prevent the formation of an uncontrollablylarge molten pool. The top pass again reverts to weld-ing with just one electrode which oscillates to producethe best possible seam surface. The second flux-coredwire is switched off again during the process. No pro-cess disruptions or disadvantageous effects on the qual-ity of the seam have so far been observed.

Figure 3. Hydraulic cylinder for moving the bucket and jib.

Figure 4. Cylinder base.

Figure 5.Cylinder head.

Cylinder base Piston Tube

Pistonshaft

Cylinder head

Figure 6.

Figure 7.


As a matter of principle, the MAG tandem method of-fers an opportunity to improve the productivity ofMAG welding. However, if this process is used with solid wire, a few typical weak points can be observed,such as a tendency towards undercutting, high contacttip wear, the need to reset the process parameters fre-quently, high thermal loads on the torch and so on.

Experience to date indicates that at least the direct-ly process-related defects can be significantly reducedby using OK Tubrod 14.11.

OK Tubrod 14.11 Welding current (A) Voltage (V) Welding speed1.4 mm / 82/18 Ar/CO2 (cm/min)

Root 350 / 360 30 / 31 60 / 622 intermediate passes 390 / 400 35 / 36 58 / 60Top layer 410 / 420 36 / 37 40 / 42(oscillating)

OK Tubrod 14.11 Welding current (A) Voltage (V) Welding speed1.4 mm / 82/18 Ar/CO2 (cm/min)

Root (single wire) 350 / 360 30 / 31 45 / 50Intermediate pass Master 400 / 410 35 / 36 80 / 85(Tandem) Slave 310 / 320 33 / 34Top pass 410 / 420 36 / 37 60 / 62(oscillating)

About the authorKlaus Blome obtained an MSc from the Technical Uni-versity RWTH of Aachen. He joined ESAB Germany in1990 as a product manager for welding consumables.Between 1992 and 1997, he was international productmanager for cored wires at Filarc Welding Industries inUtrecht. He returned to ESAB Germany in 1997. KlausBlome was recently appointed regional sales managerwest and key account manager as from January 2001.

Table 1. U-seam onhydraulic cylinders (D = 210 mm, b = 20 mm).Conventional MAG weldingwith OK Tubrod 14.11 Ø 1.4 mm.

Table 2. U-seam onhydraulic cylinders (D = 210 mm, b = 20 mm).MAG tandem welding with2�OK Tubrod 14.11 Ø 1.4 mm.

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