Single pass full penetration joining for heavy plate steel using high current GMA process

When we focus on heavy plate joining, a lot of welding processes comes in to mind like submerged arc welding, friction, electro slag welding, electro gas arc welding and so on.

These welding processes are very efficient however limited on a usage. Metal Arc Welding (GMAW) is relatively flexible in the usage but multi-layer welding is required for heavy plate since rated output of GMAW is limited up to 500A in general. Therefore, OTC Daihen decided to develop a high efficiency welding process based on GMAW platform. To achieve higher penetration, up to 19mm in a single pass a new welding system has been developed by OTC Daihen. 

There are two welding power sources which realize maximum current output of 650A, and the low frequency modulated voltage control scheme was installed into the master control of welding power source to calculate the instantaneous welding current based on the optimal gradient of external characteristic. 

The welding wire, which realizes maximum wire feed rate of 40m/ min, is fed by the wire feed unit on the shoulder of manipulator and the wire buffer with assist feed unit located on any space of this system. And the dramatically downsized and water-cooled 1000A torch, can be used with Robot manipulator OR on a special purpose machines. It is also available for manual welding process.

Conclusion
• The high efficiency robot welding system has been developed to realize the stable buried arc at the high current range.
• One pass welding can be realized with sufficient penetration with stable back bead and without any weld defect and the sufficient tolerance for any groove design is expected.
• High Deposition can be achieved with manual/Semi Automated welding system compare to available conventional welding system in Market for Co2/Mig/Mag gas.
• Overall its impact on the welding cost which reduced drastically up to 45 per cent. 

For more info, contact:
Manmohan Lal
Dy. General Manager
Head of FA Robot Sales Department,
OTC Daihen India
www.otcdaihenindia.com