WÄRTSILÄ

Wärtsilä required a robust impeller that would push the limits of design and functionality. Today, after being tested for 500 hours under incredibly rigorous testing, the results are clear — They have made a lighter, more efficient, AM-built application that opens up new business potential for the engineering giant.

THE CHALLENGE

Pump impellers are widely used in the energy industry for fluid transportation. The varying use cases — depending on their needs — require a significant level of customization. Because of this, they are produced in large numbers and kept in storage as backups. This avoids long lead times of up to 20 weeks in case of failure and guarantees uptime for a part crucial to the company’s capital.

THE SOLUTION

With additive manufacturing, applications can be printed on demand, reducing waste from having to overproduce to make things financially viable. This also reduces lead times, and the need for storage can be minimized through digital inventories, on-premises manufacturing, and higher part-performing parts. In addition, additive manufacturing can disclose new business models and solutions in the spare parts business, such as cutting out prototyping by casting.

THE COLLABORATION

To create the impeller, the project used the synergy of four major players in their respective fields: Wärtsilä, Nikon SLM Solutions, nTopology, and Oqton. Together, they empowered a modern innovation that would create an exceptional solution. On top of this, the four companies opened the door for new possibilities through their collaboration, allowing each other to learn from their expertise and knowledge.

THE APPLICATION — AN AM-BUILT IMPELLER FOR THE MARINE INDUSTRY

There was a shared interest between the companies involved in pushing the technology’s boundaries. It began with a functional redesign that would create weight reduction provided by nTopology software and the decision to realize the application on an SLM®280 PS. Further, the geometrical accuracy was increased through the pre-deformation of the simulated model with Amphyon. Combining the power of these technologies, the pump impeller was not only as light and resilient as the existing part but massively reduced the lifetime cycle/lead-time. In addition to the quick availability, the new part design will allow improvements to the system. This efficiency update can play a significant role in the energy sector by extending its technologies using additive manufacturing. Wärtsilä is open to new business opportunities arising from this.

While avoiding the need for prototyping by casting — which includes the requirement of tooling parts that cost tens of thousands of euros — the fast design and printing process allowed Nikon SLM Solutions to overcome the traditional life cycle and led to an early testing phase.

During this phase, the requirements of the pump impeller were tested in a real-scale laboratory engine with multiple measurements to indicate the performance level of the part. Real environmental conditions, such as 120 ⁰C temperature and rotational speed over 2600 rpm, were applied to validate the prototypes.

The impeller was tested at different engine loads for more than 500 hours. After the test, no signs of wear and defects were detected, demonstrating the high performance of the material used.

THE INNOVATION

The design process used the nTopology software, which offered the possibility of generating a complex lattice structure within the impeller and aligning it with the cylindrical axis, complementing the impeller design’s rotational nature. Furthermore, it allows field-driven design enabling the performance of structural analysis on the impeller to variably hollow and thicken the interior lattice beam thickness based on stress results. This gave the impeller the identical resilience as the original part, only lighter in weight.

In addition to the advanced modeling software by nTopology, Nikon SLM Solutions used a unique software that has been developed to overcome the barrier of printing surfaces with an angle less than 45 degrees: Free Float. Smart vector enables the capability of printing surfaces with an angle of 20 degrees for the application’s chosen material, IN718. Typically, surfaces with such angles require a supportive structure to be removed during post-processing. With a complex part such as a pump impeller, eliminating the supports with tools can be difficult due to nooks. Therefore, less material consumption is needed, resulting in less post-processing, both of which contribute to the productivity of the part.

THE TECH — SLM®280 PS

Featuring multiple lasers, closed-loop powder handling, and upgraded process control, the SLM®280 PS is ideal for demanding applications requiring high productivity.

INCONEL 718 — HIGH STRENGTH AND CORROSION RESISTANT

Nickel-based superalloys have been specifically designed to withstand extreme conditions in which other materials already fail. One of the most popular nickel-based superalloys is the precipitation-hardenable IN718. Whether static or dynamic loads, close to absolute zero or above 700 °C, corrosion, or creep – IN718 was made for these specifications while maintaining good weldability. This profile of properties makes IN718 an excellent choice for rocket and aircraft components, stationary gas turbines, or automotive exhaust systems.

MATERIAL CHARACTERISTICS

• High strength
• Good ductility
• Excellent mechanical properties up to to 700°C
• Excellent oxidation resistance

TYPICAL APPLICATION AREAS

• Aerospace
• Energy
• Chemical industry
• Turbine parts

DFAM — UNLOCKING THE TRUE POTENTIAL OF METAL AM

The internal geometry and lattice design followed two goals: to reduce weight while withstanding the required forces and creating stable AM process conditions. With nTopology and its field-driven design, we optimized the design quickly and came up with an optimal solution. The simulations minimize the wall thickness by considering lattices for carrying stresses.

With the field-driven design of nTopology, the lattice’s thickness was scaled to these stresses easily. To further maximize the performance of the impeller, the lattice is rotationally symmetric around the rotation axis to keep the part balanced while in use.

nTopology

With the contribution of nTopology, the collaboration included a software company building the next generation of engineering design tools for advanced manufacturing. With their vision that almost every physical object starts with engineering software, the project gained an expert in the design process and enhanced it.

Oqton

Oqton’s simulation software Amphyon (formerly called Additive Works Amphyon) enabled Nikon SLM Solutions to achieve a dimensionally accurate part to maximize its characteristics. The deformation of the component was calculated using the mechanical process simulation, considering the thermal stresses of the build process, stress relief, and support removal. Instead of meshing the complex lattice structures, a new homogenization approach was used, reducing the calculation time significantly. The entire analysis was performed within 1h 35min on a regular CAD workstation.

By creating a distortion-compensated (pre-deformed) model, a near-net-shape lightweight part with supreme properties could be delivered.

THE FACTS

• Nikon SLM Solutions successfully built Wärtsilä’s impeller on the SLM®280 PS in its application center in Germany using Free Float.
• Nikon SLM Solutions stress tested the application under extreme conditions to simulate real-life stress scenarios.
• Free Float was used with complex data, allowing the impeller massive weight reductions.
• A five percent weight reduction was achieved on IMP1.
• A 40 percent weight reduction was achieved on IMP2.
• Wärtsilä conducted a 500h testbench run under real-life conditions. IMP1 passed successfully, and IMP2 is currently being tested.
• Free Float and DfAM achieved incredible weight savings and efficiency gains.
• Geometrical deviations were below 400µm due to the usage of the distortion-compensated model.

WÄRTSILÄ

Wärtsilä is a global leader in innovative technologies and lifecycle solutions for the marine and energy markets. We emphasize innovation in sustainable technology and services to help our customers continuously improve their environmental and economic performance. Our dedicated and passionate team of 17,000 professionals in more than 200 locations in 68 countries shape the decarbonization transformation of our industries across the globe. In 2021, Wärtsilä’s net sales totaled EUR 4.8 billion. Wärtsilä is listed on Nasdaq Helsinki.

OUR MISSION, TO EMPOWER YOURS

To learn more about how Nikon SLM Solutions can help you optimize your manufacturing processes, please contact our team.