Since August 1997, automated weld positioning based on non-contact laser seam tracking equipment manufactured by Meta Vision Systems has taken over from manual control of the weld head on no less than 29 tube production lines at the Berlin factory of stainless steel pipe maker, Sosta. The resulting labour cost saving means that the investment in automation is recouped after each retrofit in just over seven months. Moreover, the operators have been released from a particularly tedious job and re-deployed elsewhere in the factory.
Payback is in reality even faster, as the above figure does not take into account the reduction in wasted pipe. Scrap inevitably resulted when positioning the weld head manually, as it is difficult for an operator not to lose concentration over long periods. Imperfect products are not an option for Sosta, as its customers within the food, chemical and pharmaceutical industries demand top quality pipework to eliminate the risk of contamination.
The pipe is roll-formed from coil into diameters ranging from 20 mm to 250 mm and TIG welded at about 250 mm/min. The weld head includes a TIG torch with wire feed followed by a second torch to reflow the weld material, giving a smooth finish. This in turn is followed by a polishing head. All welds are 100% ultrasonically tested.
