Optimized Design for 3D Printed Valve Block Sheds Weight, Size and Gains Improved Performance

The customer in this case study is Nurmi Cylinders, a Finland-based manufacturer of hydraulic cylinder products for offshore, industrial, marine and mobile hydraulics. They were one of the funders of the project and provided the valve block that was to be optimized and redesigned for additive manufacturing. Nurmi Cylinders was interested in exploring the potential benefits of additive manufacturing for their products, specifically in terms of reducing the size and amount of material needed for their valve blocks, and optimizing and improving the valve block’s internal channels to produce a better component for their customers. They worked closely with VTT throughout the project, providing the boundary conditions and additional internal limitations for the design of the valve block.

The Technical Research Centre of Finland Ltd. (VTT) was tasked with the optimization and design of a valve box with regard to additive manufacturing requirements. The project was part of a larger initiative to explore the feasibility of additive manufacturing in Finland. The valve block was provided by Nurmi Cylinders, a Finland-based manufacturer of hydraulic cylinder products. The goal was to showcase what a design specifically targeted for additive manufacturing had to look like in order to fully benefit from the manufacturing method. The objectives were to reduce the size and the amount of material needed for the valve block, and to optimize and improve the valve block’s internal channels to produce a better component for the customer. However, not every component or product is suitable for 3D printing, depending on its size, form and design as well as the quantity needed. A valve block is very suitable for 3D printing and has a high potential for improvement in weight, performance, and design freedom when additively manufactured.

To design, optimize, and analyze the valve block, VTT used Altair Engineering’s HyperWorks® CAE software suite. OptiStruct®, the optimization tool and finite element solver in the suite, was VTT’s first choice. The software allowed the engineer to define the design space and its limitations, as well as loads and other boundary conditions, and the optimization tool proposed an optimal design. To further optimize the valve block’s performance, the route of the internal fluid channels was changed. Initially these channels were curved like an S, with the cross sections having a circular shape. The solution VTT came up with, together with the customer, was keeping the same cross sectional area but changing the shape and path of the channels. One of the major goals of the project was to create ‘design rules‘ for SLM. These include guidelines such as designing an oval or diamond shape channel instead of a circular one, since this design doesn't need support structures and will result in an overall structure that can be better printed with the SLM method.

• The project was a success, resulting in an optimized design for the valve block that met all stress and strength requirements, improved fluid flow in the internal channels, and significantly reduced the component’s size and weight. The new design was also more efficient to produce, resulting in less material waste. The project also resulted in the creation of 'design rules' for SLM, which will be beneficial for future additive manufacturing projects. The success of the project has benefitted not only the customer, Nurmi Cylinders, but VTT as well. The project provided a valuable learning experience for VTT in terms of handling the 3D printing process and designing for 3D printing. The project also demonstrated the benefits of using optimization tools in the design process.

• Overall reduction of the component’s size and weight
• Improved fluid flow in internal channels
• The new optimized and 3D printed valve block weighs less than 600 grams, a 76 percent weight reduction compared to traditional design and manufacturing methods