Current Development Status and Technological Breakthroughs in Independent Manufacturing Processes for Large Ship Propellers

1. Development Background of the Large Ship Propeller Manufacturing Industry

Large ships serve as the backbone of global trade transportation, and the performance of their propulsion systems directly determines navigation efficiency, energy consumption, and operational safety. As the core component of a ship propulsion system, the manufacturing accuracy and quality of propellers have long represented one of the most critical technical challenges in the shipbuilding industry.

For many years, advanced manufacturing technologies for large ship propellers have been dominated by a limited number of overseas companies. Domestic shipbuilding enterprises have not only been required to pay high technology licensing fees but have also frequently encountered challenges such as delayed deliveries and insufficient technical support, which have constrained the high-end development of China's shipbuilding industry.

In recent years, as the global maritime industry has accelerated its transition toward green, intelligent, and large-scale development, emerging vessel types such as ultra-large container ships, LNG carriers, and fully electric intelligent vessels have imposed increasingly stringent requirements on propeller size, machining accuracy, energy efficiency, and noise reduction performance. According to industry statistics, there are currently more than 50,000 commercial vessels in operation worldwide, and the market for energy-saving retrofits of existing ships continues to expand. As a result, demand for large ship propellers is steadily increasing.

Against this background, achieving breakthroughs in independent manufacturing processes for large ship propellers is not only essential for overcoming overseas technological dependence and reducing domestic shipbuilding costs but also a key driver for transforming China's shipbuilding industry toward higher-end, smarter, and more competitive development.

From the perspective of industrial evolution, traditional large propeller manufacturing has long relied on a sequential production model characterized by fragmented processes and operations performed at different locations. This approach requires multiple steps, including initial inspection of cast blanks, rough milling, offline inspection, manual calculation of machining allowances, modification of machining programs, secondary clamping for precision machining, and manual grinding and polishing.

Such a manufacturing model results in long production cycles and heavy dependence on the experience of skilled technicians. Because large propellers must be repeatedly lifted, transported, and repositioned between different machines and workstations, each transfer introduces uncontrollable clamping and positioning errors. These accumulated deviations cause the machining reference system to shift during process transfer, significantly affecting blade surface consistency and overall manufacturing accuracy.

Meanwhile, in traditional manufacturing processes, material handling and waiting time account for more than 60% of the total production cycle. The utilization rate of core machining equipment remains relatively low, while the final full-surface manual grinding and polishing process often requires teams of highly skilled workers working for several weeks. This has become a major bottleneck restricting production efficiency and delivery schedules.

Subsequently, an improved "inspection–milling" semi-closed-loop manufacturing model based on in-machine measurement was introduced. By integrating probes or scanners into five-axis CNC machining centers, this approach enabled in-situ measurement after rough machining and automatic tool-path compensation. Although it reduced the number of clamping operations to some extent, limitations remained in measurement range, accuracy, and efficiency. Furthermore, it lacked automated finishing and polishing capabilities, meaning that final surface treatment still depended on offline manual operations. A complete closed-loop manufacturing process had therefore not yet been achieved.

Consequently, developing a new generation of independent manufacturing technologies for large ship propellers and addressing the limitations of traditional production methods have become critical challenges for China's shipbuilding industry.