Welding is the key part of the shipbuilding, and it directly related to the quality and efficiency of the ship building. Nowadays, the analog control DC arc welding machine is widely used in the production of ship and offshore plant. But the requirements of the special ship, offshore plant and high added value ship owners increase gradually. The welding quality, automatic welding, energy conservation are all put forward strict requirements. In this case, the limits of the analog welding machines are apparent. The digital welding machine instead of the analog welding machine is the direction of the development.
The welding expert database, that the digital welding machine takes, is one of important characteristics. The horizontal fillet welding is prevalently used in ship building industries to fabricate the large scale structures. A deep understanding of the horizontal fillet welding process is restricted, because the phenomena occurring in welding are very complex and highly non-linear characteristics. So in this paper, we have found the optimal relationships between welding parameters for horizontal fillet welding such as current and voltage, current and deposition rate, through literature survey, theoretical study and a lot of welding experiments by a newly developed digital welding machine.