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80 tons of quality, just-in-time – the joining procedure makes all the difference

EWM forceArc® savings box: "Welding must pay off"

Mündersbach, 18th May 2009. Supplier ISW steel components from Ennsdorf in Austria, less than 20 kilometres south of Linz, has long since been more than just an insider tip among Austria's tool machine manufacturers. Like no other, the family business with 30 employees understands all of the production steps associated with key heavy duty components, weighing up to 80 tonnes, for constructing
quality machines: from torch cutting to welding, straightening, tempering, sand-blasting and coating to machining.
Proprietor and managing director Gerhard Limberger is convinced that the joining technology is of the utmost importance. “With the investment in state-of-the-art PHOENIX Puls 521 welding power sources in combination with the forceArc® high-performance welding process from EWM HIGHTEC WELDING, our welding procedures have achieved new levels of quality and cost-effectiveness".

Heavy plate – a solid basis

The components that ISW produces for mechanical constructions are anything but lightweight. At the same time, the product range stretches from ready-to-install modules through to entire machine frames. Some customers have their parts, each weighing between 10 and 80 tonnes, delivered on a just-in-time basis to their ongoing production. The basis of all components, be it an entire housing or an individual panel, is always heavy plate: this is quality steel from the Dillinger Hütte (Dillinger Ironworks) and Dillenburger Grobblech GmbH – S235J2 (ST 37) and S355J2 (ST 52) construction steel – from 20 to 300 millimetres thick. Cutting with the torch cutting machine and chamfering the weld groove is the first stage of the production process for the parts. Welding comes next. Peter Limberger, the youngest son of the family, is responsible for both process steps. The elder son, Stefan Limberger is, in turn, responsible for the processes that follow, namely straightening, tempering, sand-blasting and coating, as well as the final machining.

All-round winner forceArc®

The welding step is of special importance for all processes, as the head of the family expressly points out: "The joining technology is of the utmost importance. The highest quality material and the best possible machining are of no value if the quality of the welding seams is not good enough. Furthermore, the welding must also pay off.”
Because unit quantities per order are normally low – the lot size is frequently one – welding at ISW is mostly performed by hand using MIG/MAG. With two exceptions: a gantry welding robot takes care of frequently occurring tasks and an automated welding station joins heavy plates together for over-dimensioned components. One of the typical tasks performed in Ennsdorf is welding steel plates, 60 to 80 mm thick, onto 200-mm thick base plates – The seam type is a fillet weld with prefabrication and many layers.
In the past, ISW used commonly available standard power sources for this task. When the company's welding machines were due to be replaced, almost two years ago, four manufacturers and their most up to date equipment, competed in a "tournament". Over a period of four weeks, all of the systems had to prove their worth to between six and eight qualified welders, in each case, in 2-shift operation. The winner was clear, as Gerhard Limberger knows: "The winner came from Austrian sales and service company EWM HIGHTEC WELDING GmbH in Gmunden in the form of the highly dynamic PHOENIX Puls 521 inverter power source in connection with the
high-performance joining process, forceArc®. At the end of the test phase, all of the welders categorically insisted on forceArc®. They were now able to produce each weld seam faster and with less spatter as well as with considerably less distortion of the work piece".

An argument that carries weight: 50 welding layers less

Two of these high-tech machines were ordered initially. The financial and qualitative benefits of the process proved to be so great that more machines were ordered – there are now six PHOENIX machines in production. There is also an EWM TRITON power source for the more seldom TIG applications. ISW's satisfaction is also reflected in further evaluations: "We especially value the fast and uncomplicated service offered locally by EWM in Gmunden as well as the qualified advice" declares the Managing Director. He is happy to explain how the innovative process has established itself and how it has changed the production chain – starting with construction: "We tried out several things in the past, especially with our thickest plates.
The seam opening angle with standard MIG/MAG welding was 30 degrees at first. We reduced it to 20 degrees and tried out narrow gap welding equipment for this. We had enormously high levels of wear and unacceptable bonding faults in the component, due to the long contact tubes that were required. For forceArc® – which only needs a standard MAG torch nozzle – we have designed the geometry at the foot of the seam to be somewhat broader but, in return, we can keep the opening angle, presently 20 degrees, very small. In this way we save a great number of filler layers.
Example: we now weld the thick 260-millimetre plates with 130 layers as opposed to 180 previously!" Limberger sees that the welding speed per meter is not higher, but – most significant – the wire yield is considerably greater. In addition, he praises the deep fusion penetration achieved with forceArc® and its excellent edge formation.
he benefits of the highly dynamic instantaneous value regulation offered by the process are even more far-reaching: "forceArc® is the first process that does not 'produce' any unwanted undercuts whatsoever. Furthermore, we now have much less weld reinforcement, which considerably reduces grinding work", and he adds "the very short spray arc has extremely high directional stability; it never wanders from the target even with free wire ends of up to 40 millimetres. This means that we can penetrate deep into the joint.
What's more, along with the increased welding quality we also save costs – on filler wire, weld shielding gas, energy and reworking.”

Savings and more savings

The fact that the concentrated forceArc® arc limits workpiece distortion because of its smaller heat-affected zone is particularly noticeable in the heavy-duty components that are produced at Ennsdorf: even the enormous straightening machine, which produces pressure of up to 600 tons, has much less work to be carried out on each component.
The company leader reveals even more aspects of saving with forceArc®: "We now need significantly fewer spare parts for our work, for instance, contact tubes for the torch. We can also work with the hose packages far longer than previously; the equation here is – less welding beads mean that the hose package is subjected to less movement and torsion.
This calculation is easy for the welding station, which lays bead for bead, metre for metre. It applies equally for manual joining with the PHOENIX power source in combination with the forceArc® technology.
The wear on contact tubes is reduced by about two thirds as opposed to our previous welding machines! We see the reasons in the fact that the PHOENIX allows excellent welding torch cooling, together with even wire feed and the precision of the arc – which neither wanders from its work point nor burns back. It is therefore the good arc properties, regulated by highly dynamic control, that make the difference.

New technology – new field of business

Like his sons, Limberger senior also sees the chance for further expansion in their innovative production equipment: "We now have a basis allowing us to produce large as well as complex components very efficiently. Along with tool machine manufacturers in Austria, Germany, the Czech Republic and Slovenia, we have also won customers in the field of alternative energy production. We offer these customers gear box housings for wind turbines.

Everything at a glance: EWM forceArc®

This process variant, patented by EWM, for metal active gas welding enables a "very short spray arc" and higher performance and excellent welding qualities at the same time. This is only possible with EWM inverter technology and its instantaneous value regulation, which is both faster and highly dynamic:
In comparison to conventional spray arcs, the EWM forceArc® process offers unbeatable economical and qualitative benefits:

Very narrow and higher pressure arc
- Excellent root and edge formation
- Deeper fusion penetration
Exceptional directional arc stability
- Welding with an extremely long free wire end
Excellent seam quality
- Almost spatter-free welding
- Prevention of undercuts
- Minimised heat affected zones and distortion
- Less additional work and reworking
Less seam volume, adjusted for the process
- Minimal weld seam preparation
- Reduced costs for material, gas and energy
- Reduced wage costs
Significantly shorter production times for the entire joining process