3D printing and additive manufacturing are different catch-all names for the same set of processes. Traditional subtractive manufacturing techniques remove material to form a part, for example on a lathe or a milling machine. In contrast, additive manufacturing either deposits material in layers or selectively hardens material to form the desired shape.
There are seven types of 3D printing technology in common use in 2021:
- Extrusion uses a heated nozzle to extrude material, such as plastic, metal, or cement, to form layers that bond as they cool.
- Vat polymerization uses a focused UV light to harden layers in a vat of photopolymer resin.
- Powder bed fusion relies on laser or electron beams to melt layers of powdered material, such as powdered metals, together.
- Material jetting employs a printhead to lay down layers of UV curable material, which are then cured by successive exposure to UV light.
- A binder jetting printhead deposits drops of binding fluid on a power substrate, hardening it in layers.
- Sheet lamination uses ultrasonic welding or adhesive to bond metal or paper ribbons. The final shape is completed by subtractive processes.
- In directed energy deposition, a multi-axis nozzle extrudes material, usually metal powders, which are then melted by lasers. This can be used for repairs, or for adding to an existing object.
All 3DP has clear summaries of the strengths and weaknesses of each technique. According to Statista, fused deposition modelling, a form of extrusion, is the most commonly used 3D printing technology in 2020; selective laser sintering, a form of vat polymerisation, is next in line.
3D printing vs traditionally manufactured parts
When it comes to 3D printing in the maritime industry, we need to consider three scenarios:
- 3D printing for rapid prototyping;
- 3D printing spare parts ashore, for delivery to ships; and
- 3D printing spare parts on board ships.
3D printing for rapid prototyping of designs is already well-established and in widespread use across maritime-adjacent industries, including automotive; energy, oil and gas; yachting; aviation; and space. Even in the maritime industry, the use of 3D printing is steadily growing.
Over the next few years, we can expect to see increases in both 3D printing parts ashore for delivery to ships, and printing small spares on board.
3D printing has the potential to reduce waste, costs, and emissions. While not perfect, it has many advantages over traditional manufacturing methods and supply chains, particularly for low-volume parts. For the maritime industry, it directly addresses several sticking points in our supply chains.
Customarily, ship spares are shipped from a central warehouse to the ship’s next port. All too often, the parts are shipped to the wrong port, they go missing in transit, the wrong parts arrive, or the required parts are no longer manufactured because the equipment is obsolete.
Customs fees, delivery delays, the cost and emissions involved in shipping parts worldwide and the costs of warehousing parts waiting to be shipped (or collected) make the traditional system costly and inefficient. And that’s without considering the cost and waste of replacing equipment when spare parts are no longer available, and the inevitable stress for the crew on board waiting for essential parts.
Because of the way 3D printers work, the only material consumed in printing a part is exactly what’s needed. Parts designed for 3D printing don’t need the heavy scantlings of cast parts so they use less material than their injection-moulded counterparts. Even better, with the right equipment, any waste from supports or failed prints can be recycled into new filament or pellets to reuse, eliminating waste altogether.
Ships carrying appropriate 3D printers have the potential to print small replacement parts like impellers, valves or pipe fittings on board. This reduces waiting time and allows many repairs to be carried out at sea where there’s more time to focus on the job, improving safety and crew well-being.
In addition, manufacturers and service technicians can keep source files for legacy parts on-hand to print-on-demand and keep older equipment operating.
Problems with 3D printing
Practical concerns
Andy Cole, chief engineer of a ship that carries a basic extrusion printer, agrees that it’s proved useful for small jobs on board; on the other hand, he questions the sense of relying on it. His reservations centre around the slow print speed, the necessity of carrying sufficient print materials, the inherent weakness of the printed parts. Like many consumer products, the printer is sensitive to the power fluctuations of the ship’s electrical system and often needs to be reset. Despite his reservations, he considers those problems surmountable and believes that with appropriate support and crew training, it has potential.
His practical concerns are valid for consumer extrusion printers. However, commercial 3D printing techniques have advanced considerably over the last few years. Since 2017, 3D printed parts using advanced print technology have been used successfully for high-load parts including propellers and crane hooks, and approved by DNV, RINA, Lloyds Register and ABS. This demonstrates that, when properly made, printed parts can be strong enough to comply with Class requirements.
Today, not all 3D printing techniques are suitable for all materials, and certain materials need specific printers designed for those materials. As the technology matures, a variety of industrial 3D printers could be kept at key ports, agents’ offices, or even on board ships.
Legal concerns
In the marine industry, the main legal concerns focus on insurance, type-approval, and intellectual property law. We covered the question of type-approval earlier. In general, if key parts are type-approved it won’t impact insurance premiums, so the primary legal concern is that of protecting intellectual property.
In 2017, Create it REAL, part of The Green Ship of the Future Consortium developed a platform that can be integrated into any fused filament fabrication (a common type of extrusion) printer. It increases print speed by a factor of five, and decrypts build files directly on the printer.
Similar to digital rights management (DRM), manufacturers using the Create it REAL system can send encrypted design files, protecting their intellectual property without negating seafarers’, technicians’, or local suppliers’ ability to print parts as required.
Maritime industry 3D printing projects
Wilhelmsen and the Ivaldi Group
Wilhelmsen partnered with Ivaldi Group in 2017 to disrupt the supply chain for marine parts by replacing the traditional supply chain process with a customized, on-demand, and more efficient process of 3D printing. Their early adopters include Carnival, Thome Group, OSM Maritime Group, Executive Ship Management and Berge Bulk.
From local micro-factories, Wilhelmsen 3D prints and delivers spare parts within hours, lowering the carbon footprint and reducing costs.
Port of Rotterdam
After a 2015 pilot project focussing on 3D printing maritime spare parts, Port of Rotterdam’s consortium expanded from sixteen to twenty-eight companies, including Fokker (aerospace) and Siemens (software development). During the pilot project, they used different materials to 3D print functional propellers, cooled valve seats, spacer rings, hinges, t-connectors, seal jigs, and manifolds to get experience and understanding of the process.
In the Innovation Dock at RDM Rotterdam, they are acquiring metal printers and setting up a permanent Fieldlab for the development of knowledge in the area of metal printing, 3D scanning, 3D design and certification.
RAMLAB
RAMLAB specializes in on-demand production of certified metal parts of up to six meters in a variety of metals and alloys using Wire Arc Additive Manufacturing (WAAM) technology. Among other projects, they worked with the Port of Rotterdam to create the WAAMpeller— a 180 kilogram Class-approved nickel aluminum bronze propeller made using WAAM.
The Green Ship of the Future Consortium
Funded by the Danish Maritime Fund, the Green Ship of the Future Consortium is an independent non-profit organization driven and financed by the members. They’re working towards emission-free maritime transport using new technologies and innovation.
With partners that include Maersk, MAN Diesel & Turbo, DNV GL, one of their projects explored 3D printing in the maritime industry, including on-board printing, large-scale 3D printing, 4D printing or repair, and reconditioning with 3D printing.
Conclusion
3D printing saves money, reduces the carbon footprint of supply chains, uses fewer resources, and is convenient for ships and crews. The processes are advancing, and the range of print materials is steadily increasing.
Now that major classification societies and several large maritime companies have given their stamp of approval, 3D printing in the maritime industry can only become more widespread as it matures.
