South Korea Will 3D Print 5-Meter Ship Propellers for the U.S. Navy

Sand casting won't cut it for 5-meter propellers

Large ship propellers have always been sand cast. The process is slow, it wastes material, and once a mold is made, design changes become expensive. A new project in South Korea aims to replace all of that with metal additive manufacturing.

UNIST's 3D Printing Convergence Technology Center and startup 3DFactory were selected for South Korea's Ministry of Trade, Industry and Energy "2026 Second Shipbuilding and Marine Industry Technology Development Project." The 54-month program totals 11 billion won, about $7.74 million, with 8.5 billion won in government funding.

The goal is to produce 5-meter-class ship propellers using wire arc additive manufacturing. WAAM melts and stacks metal wire with arc heat, building complex shapes without any mold. UNIST will lead design-for-additive-manufacturing work, controlling wall thickness by position and producing the complex curved surfaces that propellers demand.

AI is meant to fix warping before it happens

Large metal parts warp during printing. UNIST is developing reverse deformation correction technology that uses artificial intelligence to analyze design, layering, and inspection data. The system predicts thermal deformation and offsets it during the build, aiming for an autonomous, on-site process.

"The core of this project goes beyond manufacturing 5-meter-class parts to verifying DfAM and AI-based reverse deformation correction technology at full scale," said Kim Nam-hoon, head of the UNIST 3D Printing Convergence Technology Center.

The U.S. Navy is the intended customer

The partners presented the technology to U.S. officials on July 23 at the Korea-U.S. Joint R&D Technology Exchange Forum in Washington. The intended market is the U.S. Navy's vessel maintenance, repair, and overhaul business, plus procuring discontinued parts that are no longer in production.

If the propellers earn class certification, the project could become a demonstration model for MASGA, the Korea-U.S. shipbuilding cooperation initiative. Ulsan's city government has agreed to support commercialization and overseas sales channels.

Ship propellers are a perfect test case for large-format metal AM. They are big, they are expensive, and the supply chain for one-off replacements is broken. If UNIST and 3DFactory can make this work at 5 meters, smaller propellers and other marine components become straightforward follow-on products.