Tug builders and owners can consider 3D printing as a new method of manufacturing optimised propellers for future towing vessels
Propellers could in the future be produced through 3D printing (or additive manufacturing as it is more accurately known) as a consortium of companies in Europe have made considerable progress with the technology. Damen Shipyards Group has entered a co-operative consortium with the Port of Rotterdam’s RAMLAB, propeller manufacturer Promarin, software developer Autodesk and class society Bureau Veritas. RAMLAB (an initiative of Port of Rotterdam, InnovationQuarter and RDM Makerspace.
The goal of this group is to develop the world’s first class-approved 3D printed ship’s propeller, to be called the WAAMpeller. It would be a major step forward in the application of 3D printing techniques in the towage sector.
The propeller will be based on a Promarin design that is typically found on a Damen Stan Tug 1606 design. This 1,300mm diameter propeller weighs around 180kg. Using Autodesk software in the construction process, RAMLAB will fabricate the WAAMpeller from a bronze alloy using the wire arc additive manufacturing (WAAM) process.
Once the propeller has been printed, Damen’s role will continue with full-scale trials. "We will be performing a comprehensive programme that will include bollard pull and crash test scenarios," explained Damen’s research and development department project engineer Kees Custers. "Our ambition is to demonstrate that the research phase for 3D printing in the maritime sector is over, and that it can now be effectively applied in operations.” The first propeller was scheduled to be printed during the third quarter of this year and then tested during the fourth quarter.
Damen principal research engineer Don Hoogendoorn sees the development of a 3D printed propeller as part of the company's drive to build more effective, more cost-efficient and more environmentally friendly tugs. He explained: “The WAAMpeller project contributes to this goal because not only does it mark an important advance in 3D printing, but also it has the potential to yield significant results in optimising future vessel designs. 3D printing technology brings with it an excellent opportunity to improve ship structures in terms of both performance and fuel consumption.”
RAMLAB is the first field lab equipped with 3D metal printers that focuses on the port and towage sectors. It uses additive manufacturing to develop knowledge in the field of metal printing, 3D design and certification. Bureau Veritas will be involved in the certification of the completed product, in what will be the first time that a metal 3D printed maritime component is approved by class.
The combination of an electric arc as a heat source and wire as feedstock has been researched for additive manufacturing purposes since the 1990s, although the first patent was filed in 1925. WAAM hardware currently uses standard, off-the-shelf welding equipment – the welding power source, torches and wire feeding systems. Motion can be provided either by robotic systems or by computer numerical controlled gantries.
Whenever possible, magnesium in gas is the process of choice. Here, the wire is the consumable electrode, and its coaxiality with the welding torch makes it easier to work. Magnesium in gas is ideal for materials such as aluminium and steel, but with titanium the process is affected by arc wandering (deflection of the arc), so tungsten inert gas or plasma arc welding are used for titanium deposition.