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ESAB AUTOMATED BEAM WELDER CUTS THE COST OF FABRICATING CUSTOM BEAMS
Furthermore, the company has a patented design of steel open floor beam, the fabrication of which is now being carried out using an ESAB automated beam welder supplied following lengthy discussions with Willie Reddy, Sales Engineer, for ESAB Group (Ireland) Ltd. Prior to making the investment in the beam welder, IJM bought in standard I-beams and used two MIG welders to manually weld an additional plate to the bottom. While the process was adequate for the purpose, it was clearly an inefficient means of performing a relatively simple task. It was also an inefficient use of materials, as the resultant fabrication contained considerably more steel than was strictly necessary. IJM therefore redesigned the beam to be fabricated from three plates: a 100 x 12mm plate on the top, a 150 x 6mm web and a 250 x 10mm plate at the bottom (other variants are also produced) with lengths ranging from 6m to 12m. The company then took a close look at various automated submerged arc welders available on the market. Michael McKinney, IJM's Maintenance Manager, explains why ESAB was selected as the supplier: "ESAB had the edge in terms of technology, especially the following system that keeps the weld head in exactly the right place. We were also able to visit companies where similar equipment was in use and they were all extremely complimentary about ESAB and the equipment, both in terms of the weld quality and the reliability of the machines." The new equipment consists of an ESAB manipulator mounted on a compact 15m track that requires minimal floor space. While the carriage is driven along the track at 1.3m/min to weld the beam components, operators are able to unload a finished beam from a parallel fixture and load another set of components ready for welding. The boom rotates between the fixtures, enabling changeover times to be very fast. Twin ESAB A6 welding heads perform the submerged arc welding concurrently on either side of the web, and twin wires are fed to each head via specifically designed contact tubes. An onboard ESAB TPC 75 pressure tank feeds flux to the welding heads and an air-operated flux recovery system is also installed on the carriage for efficient flux re-circulation. Welding voltage and current (typically 580A and 29V) are set on the PEH 1 control units, which then monitor the actual values to ensure they are within tolerance. Welding power is supplied by a pair of ESAB LAF welding power sources, and all controls other than the welding parameters are located on a remote control unit that the operator can use anywhere on the machine while the components are being positioned and welded. Two PEH control units each receive a tacho feedback signal from a VEC motor that drives the carriage along the rail. Accurate positioning of the welding heads is achieved by means of ESAB GMD guidance units that control the vertical slides and the horizontal position of the carriage. In addition to the ESAB beam welder, IJM is also using 2.4mm diameter OK Tubrod 14.00S tubular wire and OK Flux 10.71, a basic agglomerated flux that is characterised by excellent slag detachability and smooth side-wall blending. As Michael McKinney explains, "We have definitely had better results with this combination of wire and flux than with anything else we have tried. The finish is excellent, the slag is easy to detach, and no post-weld finishing is required whatsoever." To help IJM get the best out of the equipment, ESAB's engineers came on site to train the operators. They also arranged for sample welds to be tested in order that the necessary approvals could be granted. Michael McKinney comments: "We have been very, very pleased with the machine and with ESAB as a supplier. The technical support we have received has been excellent, and we have had no trouble at all with the machine. In fact we have also purchased a pair of 500A Mig welders on the strength of our experience with the beam welder." Clearly fabricating a beam from flat plate is a different proposition from adding a plate to an existing beam, but the new machine will easily pay for itself through reduced materials costs and labour. According to Michael McKinney, "If the housing market stays buoyant the payback period might be two years. And even if there is a downturn, we expect payback to be around three to four years."
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