A prototype of the world's first approved ship propeller has been produced through 3D printing techniques. The 1,350mm diameter propeller, named WAAMpeller, is the result of a collaborative consortium consisting of Damen Shipyards Group, RAMLAB, Promarin, Autodesk and Bureau Veritas.
The certified WAAMpeller was made from a Nickel Aluminium Bronze (NAB) alloy at the Rotterdam Additive Manufacturing LAB (RAMLAB) in the port of Rotterdam. We previously wrote an article on Maakindustrie.nl about the opening of this 3D lab for shipbuilding and offshore.
It was produced with the so-called Wire Arc Additive Manufacturing (WAAM) method using a Valk welding system and Autodesk software. The triple blade structure uses a Promarin design 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.
Material properties
The prototype of this 3D-printed propeller represents a steep learning curve of understanding material properties. 'This is because 3D-printed materials are built layer by layer,' says Kees Custers, Project Engineer in Damen's R&D department. 'As a result, they show different physical properties in different directions, a characteristic known as anistropic. Steel or cast materials, on the other hand, are isotropic - they have the same properties in all directions.'
Because of this crucial difference, one of the first steps was to roll out extensive testing of the material properties of the printed material to ensure they meet the standards of Bureau Veritas (a classification society). 'This involved printing two simple walls of material - after which a grinder was used to produce samples for lab tests around tensile and static strengths.'
Milestone
It can also be said that the 400-kg WAAMpeller is a milestone in terms of 3D printing production technologies. Custers: 'The challenge was to translate a 3D CAD file on a computer into a physical product. And that was even more complex because this propeller has a double-curved, geometric shape with some tricky overhanging sections.'
'Material characterisation and mechanical testing played an important role in this project,' says Wei Ta, researcher from the University of Twente at RAMLAB. 'We need to make sure that the material properties meet the needs of the application. For example, the toughness of the material is important - this ensures that the propeller can take a beating without being damaged.'
Second prototype
RAMLAB's capacity allows for the printing of objects with maximum dimensions of 7x2x2 metres. Ya: 'For large-scale 3D metal deposition, the WAAMpeller is groundbreaking for the marine industry. This technology is a fundamental change in the concept of how we make things. With additive manufacturing, you can print most metal components needed. There is so much potential for the future - these technologies will have a big impact on the supply chain.'
In particular, the first prototype of the WAAMpeller will be used for demonstration purposes. Plans for a second prototype have already been made. 'We will start producing a second certified propeller next month,' said Custers. 'In doing so, we will use all the lessons learned over the past few months. Our goal is to install the second propeller on one of our ships later this year.'
By: Kelly Bakker
Source: Damen
