Optimising Industrial Valve Block for Additive Manufacturing: A Case Study of VTT and Nurmi Cylinders

• Functional Applications - Manufacturing Execution Systems (MES)

• Equipment & Machinery
• Metals

• Product Research & Development
• Sales & Marketing

• Additive Manufacturing
• Rapid Prototyping

VTT, a leading research and technology centre in Finland, partnered with Nurmi Cylinders, a Finnish manufacturer of hydraulic cylinder products, to optimise a valve block for demanding industrial applications using Additive Manufacturing (AM). The challenge was to design a valve block that would fully benefit from the AM process, reducing its size and the amount of material needed, and optimising its internal channels to produce a better component for the customer. Traditional manufacturing methods for valve blocks involve forming a block of metal into the desired shape and drilling internal channels to accommodate hydraulic fluid flow. This process is often cumbersome and prone to alignment issues and potential leakage. Furthermore, not every component or product is suitable for AM, depending on its size, form, design, and the quantity needed.

The customer in this case study is Nurmi Cylinders, a Finnish manufacturer of hydraulic cylinder products for offshore, industrial, marine and mobile hydraulics. Nurmi Cylinders was one of the funders of the project and provided the example of a valve block to be optimised for Additive Manufacturing. The company provided the boundary conditions and additional internal limitations for the design of the valve block, including where the valve had to be placed and which machining tolerances had to be considered. The size, position and orientation of the internal channels were also chosen by Nurmi Cylinders and were part of the non-design space.

VTT engineers used Altair Engineering’s HyperWorks® CAE software suite to design, optimise and analyse the valve block. The optimisation tool and finite element solver in the suite, OptiStruct®, was used to propose an optimal design based on the defined design space, limitations, loads and other boundary conditions provided by the customer. The optimised design was then re-meshed and re-analysed using OSSmooth, one of OptiStruct’s shape generation tools, to ensure that all initial design requirements were met and stress limits were not exceeded. To prepare the optimised mesh for printing, VTT used a software application called 3-maticsSTL from Materialise, which enabled design modification, re-meshing and the creation of 3D textures, lightweight models and conformal structures. The valve block went through several design iterations, with the route of the internal fluid channels being changed to optimise performance. The final design was printed using Selective Laser Melting (SLM) machines.

• The project resulted in the successful design and manufacture of an optimised valve block using Additive Manufacturing. The optimised design was smaller, lighter and had improved internal channels compared to traditionally manufactured valve blocks. The project also resulted in the creation of design rules for Selective Laser Melting (SLM), including guidelines for designing oval or diamond shape channels instead of circular ones, and for running internal channels at a ~45° angle to the base plate to reduce the number of external supports needed. These design rules can be used to optimise the design of other components for SLM, saving time and money spent on support removal in the post-processing phase.