On the 7th at the HD Hyundai Heavy Industries Yongyeon Plant in Nam-gu, Ulsan. Entering a ship block shop the size of 48 soccer fields (about 340,000 square meters), the deafening roar of cutting and attaching thick steel plates pierced the ears. Sparks from welding were flying everywhere, but the torches were not held by people; they were held by arm-shaped robots. Instead of squatting with thick welding masks on, workers in light work clothes carried tablet PCs and moved among four robots, acting like conductors. Workers said in unison that it was a scene hard to imagine just three years ago.
Ships are made by joining multiple blocks together like Lego. The inside of a block is narrow and complex in structure, and has been considered a barren ground for automation. Now, even inside the block, a small robot 13 centimeters wide, 75 centimeters long, and weighing 14 kilograms was entering to weld in place of people. Kim Bong-seok, head of the mid-sized ship automation innovation department, said, "To weld in a cramped space inside a block, a person has to force the body in and match the electrode angle and speed, so there is a limit to increasing output," and "By contrast, a robot handles four times the amount of welding one person can patch up in a day."
◇ With a few taps, call up dimensions and weld nonstop
Data that used to be dominated by tape measures and soapstone marks in the shipyard is all being connected. In the lower block process for a 45,000-ton-class petrochemical product carrier (PC ship) that day, when a worker tapped a tablet PC screen a few times, the design drawing information popped up and a robot rode the rail to move precisely to the designated welding section. Even without the worker entering each dimension, the robot performed the job under optimal welding conditions based on plate thickness. So-called "design-to-production consolidation" was realized.
Immediately, the robot scanned the thick-plate joint with a laser sensor for about 60 seconds to grasp the groove's position, width, and depth, then began fillet welding on the internal gap where the pieces met at a right angle. Finishing the weld on a 1-meter right-angle section in under four minutes, the robot moved without delay to the adjacent section and continued the work.
The mid-sized ship division of HD Hyundai Heavy Industries plans to fully expand adoption of a system starting next month in which a robot arm rides rails and welds automatically. Using this system, one worker can operate up to eight robots simultaneously.
What stood out most where the robot passed was the result. When a person welds directly, the weight of the equipment and fatigue make force control inconsistent, making the weld line prone to becoming bumpy. As a result, a finishing process that grinds the surface smooth with a grinder had to follow without fail.
But the robot sensed changes in current and voltage and corrected its trajectory on its own even if the weld line deviated slightly, leaving a bead as smooth as if machined. With no separate finishing needed, the introduction of robots has effectively shrunk a noisy, dusty post-process.
◇ From master-apprentice transfer to AI learning… filling the gaps left by skilled workers
Robots are taking root as a practical alternative at shipyards suffering from a severe labor shortage. The positions of domestic skilled workers who left en masse during the shipbuilding downturn eight years ago are now being filled by foreigners. At HD Hyundai Heavy Industries, foreign workers number about 8,400, or roughly 19% of all employees.
But it is hard to see them as a complete labor solution. Field workers said, "Because of visa issues and other factors, foreign workers turn over frequently, making it structurally difficult to pass down high-skill techniques."
In a process where 50 to 60 people typically form a team, skilled workers make up around 20%. Bang Byung-ju, head of the mid-sized ship Yongyeon DM department, said, "Many tasks require workers with 5 to 10 years of experience, but the workforce is aging and insufficient," and "So high-skill workers focus on the most difficult areas, and for relatively standardized sections, we train lower-skill workers who can operate robots and deploy them to balance production efficiency."
The master-apprentice transfer culture on the shop floor is gradually being left as data assets and evolving into "AI robots." HD Hyundai Heavy Industries is training AI with the work data it is currently accumulating, and plans to move to a fully autonomous welding stage where robots recognize and work on blocks of various shapes on their own.
To that end, 27 collaborative robot systems from Rainbow Robotics and JCT were deployed on site starting this month. Rainbow Robotics' robots, which apply three-axis wrist rotation technology, were further optimized for the harsh shipyard environment with precision linkage technology from JCT, a welding automation SI company, enabling the robot and welder to respond as if they were one. HD Hyundai Heavy Industries plans to supply these robots to partner worksites as well and share operating know-how.
Other shipbuilders are also accelerating robot adoption. Hanwha Ocean plans to invest 300 billion won by 2030 to raise its automation rate to 70%. It has already introduced a ship piping welding robot to cut job preparation time by about 60%, and has deployed more than 80 robots in hazardous spaces such as confined areas. Samsung Heavy Industries is likewise fully applying robots to section steel and template cutting and subassembly welding processes, drawing up a blueprint for a shipyard that runs unmanned 24 hours a day.