On the 7th at the Yongyeon plant of HD Hyundai Heavy Industries in Nam-gu, Ulsan. As we entered the ship block factory the size of 48 soccer fields (about 340,000㎡), the deafening roar of cutting and joining thick steel plates pierced our ears. Welding sparks were flying in all directions, but the torches were gripped not by people, but by robots shaped like human arms. Instead of crouching with thick welding masks on, workers in light work clothes held tablet PCs and moved among four robots, playing the role of conductors. It was a scene workers said would have been hard to imagine just three years ago.
Ships are made by joining multiple blocks together like Lego. The inside of a block has long been considered barren ground for automation because the structure is narrow and complex. Now, even inside blocks, 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 the cramped space inside a block, a person has to force the body in and match the electrode angle and speed, so there are limits to increasing throughput," and added, "By contrast, a robot handles four times the amount of welding a single person can fill in a day."
◇ With a few taps, call up dimensions and weld nonstop
Data across the shipyard, once filled with tape measures and chalk marks, is also being consolidation. In the lower block process of a 45,000-ton petrochemical product carrier (PC ship) that day, when a worker tapped a few times on a tablet PC screen, 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 task under optimal welding conditions based on thickness. The so-called "design-to-production integration" was realized.
Immediately, the robot used a laser sensor to scan the butt joint of the thick plate for about 60 seconds to identify the position, width and depth of the groove, then began welding the internal gap where the plates met at a right angle. The robot finished welding a 1-meter right-angle section in under four minutes, then moved without delay to the next section to continue working.
The mid-sized ship division of HD Hyundai Heavy Industries plans to begin full-scale expansion next month of a system in which robot arms ride rails and weld automatically. With this system, a single worker can operate up to eight robots simultaneously.
What stood out most in the robot's wake was the result. When people weld directly, the line tends to become bumpy because it is hard to keep force control steady due to equipment weight and fatigue. As a result, a finishing process with a grinder to smooth the surface had always been required.
But the robot sensed current and voltage changes and corrected its own path even if the welding line deviated slightly, leaving the weld bead as smooth as if it had been machined. Because no separate finishing was needed, one noisy, dusty post-process has effectively been reduced with the robot's introduction.
◇ From master-apprentice transfer to AI learning… filling the gap left by skilled workers
Robots are taking hold as a practical alternative on shipyard floors suffering from a severe labor shortage. The positions of Korean skilled workers who left in droves during the shipbuilding downturn eight years ago are now being filled by foreigners. At HD Hyundai Heavy Industries, foreign workers number about 8,400, roughly 19% of all employees.
But it is hard to see them as a complete workforce. Field workers said, "Because of visa issues and other factors, foreign workers are frequently replaced, making the transfer of high-skill techniques structurally difficult."
In processes where teams of 50 to 60 typically work, skilled workers make up only around 20%. Bang Byung-ju, head of the mid-sized ship Yongyeon DM department, said, "There are many tasks that require talent with five to 10 years of experience, but the workforce is aging and short," and added, "So high-skill workers focus on high-difficulty areas, while we train lower-skill workers who can operate robots for relatively standardized sections to balance production efficiency."
The shop-floor master-apprentice culture is gradually remaining as a data asset and evolving into "AI robots." HD Hyundai Heavy Industries is training AI on the work data it is currently accumulating and plans to move to a fully autonomous welding phase in which robots recognize and work on various block forms on their own.
To that end, 27 collaborative robot systems from Rainbow Robotics and JCT were deployed to the field this month. JCT, a welding automation specialist SI company, added precision linkage technology that helps the robot and welder respond as one to Rainbow Robotics' robot with three-axis wrist rotation technology, optimizing it for the harsh shipyard environment. HD Hyundai Heavy Industries plans to supply these robots to partner sites and share operating know-how.
Other shipbuilders are also speeding up robot adoption. Hanwha Ocean plans to invest 300 billion won by 2030 to raise its automation rate to 70%. It has already introduced ship piping welding robots, cutting 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, sketching out a blueprint for a shipyard that runs unmanned 24 hours a day.