[ Welding ]
[ Welding ]
Practical industry applications of inert gas flow analysis
Until recently , precise imaging methods to aid in the selection of inert gas parameters during welding were used exclusively in academic research . Wolfram Industrie has managed to bridge the gulf between academia and weld shops to optimise TIG welding processes for industrial applications .
By Matthias Schaffitz , Application Engineer at Wolfram Industrie
Downstream inspection and rework account for about 50 % of the TIG welding cost on average . With stricter quality standards , the proportion of these work steps quickly increases to two-thirds of the production process because tighter inspection cycles and more elaborate repair welding may be required . The effort can be considerably reduced through the selection of the inert gas parameters . However , these factors can usually be evaluated only based on their effects . A correction is possible at best for the next workpiece and may necessitate changes to other process factors . Streak methods can help determine the inert gas parameters in a timely manner . However , precise imaging methods have been used exclusively in academic research to date . Their transfer to industrial practice was hardly feasible . Wolfram Industrie has built a bridge across this seemingly insurmountable
Oxidation of a tungsten electrode . Photo : Gesellschaft für Wolfram Industrie mbH chasm between industry and research . Through a combination of streak methods and sensor measurements , Wolfram Industrie ’ s Swiss welding laboratory now offers development services and consulting to optimise the TIG welding process especially for industrial applications .
Avoiding weld defects If the electrode oxidises , for instance , because the inert gas flow setting is too low , the component oxidises as well . TIG welding takes place in a closed system with interactions between individual components : the tungsten electrode , welding seam and inert gas . This is associated with some challenges . Depending on the field of application , a porous or otherwise defective welding seam on a component , for example , can have fatal consequences . Furthermore , the welding process – joining the components – often occurs relatively late in the value chain . Quality defects that occur at this late stage can , therefore , painfully slow down production as a whole . Inert gas protection is , however , an influencing variable that cannot be determined intuitively . Recommendations are usually general in nature and can deviate considerably from the configurations actually required in a specific application . Difficulties such as electrode wear , ignition problems or material defects are often caused by an excessive gas flow that is highly turbulent or by an insufficient flow rate that , in turn , makes the inert gas protection more susceptible to air turbulences and draughts in the workplace . Thus an unsuitable
Matthias Schaffitz , Application Engineer at Wolfram Industrie GmbH ’ s research and production centre in Winterthur , Switzerland . Photo : Gesellschaft für Wolfram Industrie mbH
configuration of the inert gas supply quickly turns the TIG welding process into a costly undertaking .
Costly rework and lost production Rework to correct quality defects that occur in the welding process is one of the biggest cost factors . This includes repair welding to remove peripheral oxidation and thus improve the surface condition . Non-destructive material testing is also performed , for example , testing the porosity of the welding seam in the microscopic range . While oxidation is caused by its namesake oxygen , porosity in the metal is often due to nitrogen or hydrogen . Both can usually be traced back to improperly configured inert gas protection and be eliminated by a process improvement . Machine availability is also becoming more important with the rising automation level in production . Sophisticated and costly welding cells , orbital systems and automation , in general , require a high rate of capacity utilisation to be economically viable . That being said , the tungsten electrode that is used can throw a monkey wrench in the works . Turbulent gas flows cause even high-grade electrodes to
12 Stainless Steel World December 2024 www . stainless-steel-world . net