FOCUS ON WELDING
The protective gas is an influencing variable that cannot be intuitively determined .
The effects of the inert gas can generally be determined only by observing the effects .
TIG welding in focus
If the electrode oxidises ( e . g . because the inert gas flow setting is too low ), the component also oxidises . TIG welding takes place in a closed system with interactions between individual components : the tungsten electrode , welding seam and inert gas . This can also bring challenges .
Depending upon the application , a porous or otherwise defective welding seam on a component , for example , could 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 slow down overall production .
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 required in a specific application . Difficulties such as electrode wear , ignition problems or material defects are therefore often caused by an excessive gas flow that is highly turbulent , or by an insufficient flow rate that ( in turn ) makes inert gas protection more susceptible to air turbulence and draughts in the workplace . An unsuitable configuration of the inert gas supply can therefore quickly turn the TIG welding process into a costly undertaking .
Costly rework and lost production
Rework to correct quality defects that occurred in the welding process is one of the greatest cost factors . This includes repair welding to remove peripheral oxidation and improve the surface condition . Non-destructive material testing is also performed e . g . 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 eliminated by a process improvement .
Machine availability is also becoming more important with rising automation levels 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 said ,
Above : WS2 ® WITSTAR ® TIG welding electrodes from Wolfram Industrie .
Above : WP – Pure tungsten electrodes for TIG welding from Wolfram Industrie .
Oxidation of a tungsten electrode .
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