Using 3D printing techniques, a prototype of the world’s first class approved ship’s propeller with a diameter of 1,350mm has been manufactured. The propeller has been named ‘WAAMpeller’ and is the result of a cooperative consortium of companies that includes Damen Shipyards Group, Promarin, RAMLAB, Autodesk, and Bureau Veritas.
3D printed materials science
The first prototype WAAMpeller will be used for display purposes, and planning for a second example is already underway. This prototype represents a steep learning curve of the understanding of material properties. “This is because 3D printed materials are built up layer by layer,” says Kees Custers, Project Engineer in the R&D department of Damen. “As a consequence, they display different physical properties in different directions – a characteristic known as anisotropy. Steel or casted materials, on the other hand, are isotropic – they have the same properties in all directions.”
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WAAMpeller was fabricated from a Nickel Aluminium Bronze (NAB) alloy at RAMLAB (Rotterdam Additive Manufacturing LAB) in the Port of Rotterdam. The propeller was produced with the Wire Arc Additive Manufacturing (WAAM) method using a Valk welding system and Autodesk software. The triple-blade structure uses a Promarin design that is used on Damen’s Stan Tug 1606. With production complete, the WAAMpeller will be CNC milled at Autodesk’s Advanced Manufacturing Facility in Birmingham, UK.
It is because of this critical difference that one of the first steps consisted of carrying out extensive testing of the properties of the printed material to ensure compliance to Bureau Veritas’ standards. “This involved printing two straightforward walls of material – then using a milling machine to produce samples for lab testing of tensile and static strengths,” Mr Custers explains.
Meeting application needs
3D printing opens up new ways of manufacturing. “There is so much potential for the future – these techniques will have a big impact on the supply chain,” says Wei Ya, Postdoctoral Researcher from the University of Twente at RAMLAB. “Material characterization and mechanical testing have been an important part of this project; we have to make sure that the material properties meet the needs of the application.” An example is material toughness, to make sure the propeller will be able to absorb significant impact without damage. “For large scale 3D metal deposition, the WAAMpeller is really ground-breaking for the maritime industry,” Mr Ya concludes.