Project overview
Industry: Maritime
Application: Marine propeller
Material: Nickel Aluminium Bronze
Manufacturing process: WAAM
Project focus: Material development
Partners: D.E.E.P. Consortium
Status: Completed
Developing the next generation of marine propellers
The Digitally Enabled Efficient Propeller (CMDC6) project was a seven-month Innovate UK-funded feasibility study exploring how Wire Arc Additive Manufacturing (WAAM) could transform the production of marine propellers.
Working alongside Enki Marine, Stone Marine Propulsion, TWI, Authentise, ASTM International and Newcastle University, DEEP Manufacturing was responsible for developing and manufacturing a section of a marine propeller blade in Nickel Aluminium Bronze (NAB) using WAAM.
Unlike conventional solid propellers, the demonstrator incorporated an internal cavity designed to support future lightweighting, acoustic performance and digital monitoring technologies. Producing this complex geometry using additive manufacturing would help demonstrate a new approach to manufacturing marine propulsion components with greater design freedom, reduced material waste and shorter lead times than traditional casting.
Manufacturing complex internal geometry
Conventional casting limits the design freedom available for marine propellers. This project explored whether WAAM could manufacture a propeller blade with an internal cavity, enabling lighter, more advanced designs that would be difficult or impractical to produce using traditional methods.
Developing a qualified manufacturing process
Nickel Aluminium Bronze is widely used for marine propulsion, but manufacturing complex components with WAAM requires carefully developed process parameters. The project set out to establish a repeatable manufacturing route capable of producing high-integrity components for future marine applications.
Our approach and results
To demonstrate that complex marine propulsion components could be manufactured using WAAM, DEEP Manufacturing began by developing a robust manufacturing process for Nickel Aluminium Bronze (NAB). This material is widely used for marine propellers due to its excellent corrosion resistance and mechanical performance.
The project began with the development and optimisation of multiple deposition parameter sets to accommodate varying wall thicknesses and heat inputs. The process was continually refined, progressing from single-bead trials to multi-bead deposition before manufacturing representative test blocks for metallurgical assessment.
Material performance was then assessed through mechanical, fatigue and corrosion testing, alongside microstructural examination. Additional builds were produced to investigate through-thickness properties and different heat treatment processes before progressing to the final demonstrator.
Material: Nickel Aluminium Bronze (NAB)
Wire: EN ISO 24373 CuAl9Ni5Fe3Mn2 / AWS A5.7 ERCuNiAl
Grade: NV Cu 3
Dimensions: 815 × 400 mm; 828 mm across diagonal
Weight: 413 kg
Yield strength: 36 ksi
UTS: 86 ksi
Elongation: 16%
Material performance
Corrosion testing demonstrated excellent resistance compared with bulk/wrought material after 30 days, while fatigue testing produced encouraging results. Through-thickness and heat-treatment studies also concluded that material properties met or exceeded the base material specification.
Confidence in WAAM
The project established a repeatable manufacturing approach, from process development to component production. Testing demonstrated encouraging material performance, providing a strong technical foundation for the future development of WAAM-produced components.
New design possibilities
Removing many of the constraints associated with traditional casting, WAAM enables greater design freedom for marine components. Internal cavities, near-net-shape manufacture and optimised geometries have the potential to improve performance while reducing material waste and lead times.
Future of marine manufacturing
As demand grows for more efficient and resilient manufacturing, qualified WAAM offers an alternative route for producing low-volume, high-value marine components. Projects such as CMDC6 help build confidence and technical understanding for industrial adoption.
Related topics
Find out more about the project and about DEEP Manufacturing's capabilities.
How was WAAM-produced Nickel Aluminium Bronze tested for marine applications?
The material underwent mechanical, fatigue and corrosion testing alongside microstructural examination. Bend testing used a former diameter three times the material thickness (3T), while Charpy impact testing was carried out at 0°C, -20°C and -40°C.
How did WAAM-produced Nickel Aluminium Bronze perform in corrosion testing?
Three types of corrosion testing were undertaken: immersion corrosion, galvanic corrosion and stress corrosion cracking. After 30 days, immersion and galvanic testing demonstrated excellent corrosion resistance compared with bulk/wrought Nickel Aluminium Bronze material.
How did WAAM-produced Nickel Aluminium Bronze perform in fatigue testing?
Fatigue testing produced encouraging results compared with wrought material. Four of the nine specimens reached 2,000,000 cycles without failure, with the highest stress range tested at 64 ksi.
Were through-thickness properties assessed in the WAAM build?
Yes. An additional thick-walled section was manufactured specifically to investigate properties in the through-thickness direction, providing further understanding of material performance beyond the primary build orientation.
How did heat treatment affect the WAAM-produced Nickel Aluminium Bronze?
Three additional test blocks were manufactured to investigate different heat-treatment processes. Across the development and testing programme, the project team concluded that the resulting material properties met or exceeded the applicable base material specification.