Hydraulic manifold for aerospace redesigned for additive manufacturing with MTC, part-2 (systems-level) redesign

Extra stock material is added to the larger ports to allow for post-machining of the manifold to the correct tolerances

In this post, which follows on from part 1 (hydraulic manifold for aerospace redesigned for AM with MTC, part-1), we will look at how we redesigned this hydraulic manifold from a systems-level redesign perspective. By removing some constraints in the design process and moving the positions of the inlets and outlets of the manifold, we overcame some of the challenges with powder removal that we experienced with the initial design. In part 3, we will share and review the results of this manifold redesigned for additive manufacturing. Read on to find out more.

The first hydraulic manifold redesign

In part 1, we considered a manifold redesigned for additive manufacturing. Specifically, this was a hydraulic manifold for an aerospace application in collaboration with the MTC. In the first manifold redesign, we kept the positions of the inlets and outlets of the manifold in the same position. This is often one of the constraints of a manifold redesign. However, upon inspection of the printed manifold, we discovered that powder removal was a significant challenge due to the formation of the “sintercake” in the EBM process.

Hydraulic manifold re-designed for AM in the aerospace industry
Hydraulic manifold designed for the aerospace industry

A root cause analysis was performed on the design and we determined that the powder removal challenges could potentially be overcome by reducing the lengths of fluid channels and ensuring line of sight access to the powder to facilitate easier powder removal.

Fluid channel redesign

With this in mind, the design teams at Gen3D and the MTC experimented with the design and tested what would happen if we took a systems redesign approach. If you look at the commitment-benefit curve graph, we can see that systems-level redesign requires the biggest commitment to the process. This is because you may have to move other components within the subassembly, however, this also gives the biggest opportunity for gains during the redesign of any manifold redesigned for additive manufacturing.

Commitment vs benefit curve showing how parts can be redesigned for the additive manufacturing process
Commitment vs benefit curve showing how parts can be redesigned for the additive manufacturing process

In comparison to more traditional CAD software, Gen3D’s Flow module allows users to quickly redesign fluid channels. This meant that we could quickly modify the component-level redesign from part 1 to the systems level second-generation part in less than a day.

The comparison between the two models can be seen in the following figure.

Gen3D Manifold Comparison - hydraulic manifold - additive manufacturing
Comparison of the component-based redesign (shown left) and systems-level redesign (right) of a hydraulic manifold in the aerospace industry.

You can see from the two images that the systems-level redesign is a far more compact design. Additionally, we have made use of the compensation feature to add both teardrop shapes to the top of the fluid channels where necessary, We’ve also added a teardrop shape to the bottom of the fluid channels to reduce the total amount of required support structure.

Design for post-processing

After the fluid channels, we followed a similar methodology to part 1, with the loads, constraints, design spaces and void spaces being defined inside of Autodesk Fusion 360 Generative Design program.

However, there were a few key differences in the post-processing.

Firstly, we added two additional powder removal ports to the design. These were placed in locations where trapped powder had been found in the first iteration, but where we couldn’t redesign to get line-of-sight access to the powder.

Additional powder removal port of hydraulic manifold
Powder removal ports added to the hydraulic manifold to facilitate powder removal. This is particularly important with the EBM process due to the formation of the sintercake during the build.

This is somewhat counterintuitive since one of the benefits of additive manufacturing is the potential reduction of the number of components in an assembly. However, sometimes it can be beneficial to keep extra features in, such as powder removal ports, to reduce time, effort and cost when post-processing your parts.

The second difference is in the stock material and fixturing. In this case, since we had the option to move some of the channels, we could keep all of the fixturing on the bottom of the part and machine all of the ports on a 5-axis machine in a single setup.

In this case, with a single prototype part, the cost difference isn’t huge, but for a production run, this change could result in significant cost savings. Finally, we reduced the amount of stock material by modifying the internal shape of the fluid channels to a modified diamond shape where applicable.

Extra material added to the hydraulic manifold redesign for additive manufacturing
Extra stock material is added to the larger ports to allow for post-machining of the manifold to the correct tolerances.

Testing and inspection of the manifold

To test whether the updates to the design have improved the performance of the manifold. The MTC performed a series of inspection methods on the manifold. These include both fringe projection, using a GOM scanner and also X-ray CT scanning to check for trapped powder within the fluid channels.

Fringe-projection scan of manifold overlaid on the CAD model
Fringe-projection scan of the as-built manifold is overlaid on the CAD model to check for deformation during the build. This can be fed into the CNC toolpath to ensure accurate machining.

In the case of this manifold, the powder was able to be fully removed from the manifold and only a small amount of deflection occurred over the first manifold and this was mostly located around areas that were in contact with the support structures. The removal of all the powder meant that it was possible to continue along the additive manufacturing workflow to machining of the port interfaces.

Machining the port interfaces

In order to achieve the correct fit with the interfacing components, the ports of the manifold have to be post-machined. In this manifold, the fixturing has been designed to attach the manifold down to the CNC workholding. The ports are then measured using an on-machine touch-trigger probe to accurately determine their location and then the ports are machined to specification on a CNC milling machine.

Overcoming some of the challenges with powder removal

In this post, we looked at redesigning an aerospace hydraulic manifold from a systems-level redesign perspective. By removing some constraints on the design process and opening up the possibility to move the positions of the inlets and outlets of the manifold it was possible to overcome some of the challenges with powder removal. The manifold was then machined to ensure that the interfacing components could be assembled with the manifold.

In part 3 of this “manifold redesigned for additive manufacturing” blog series, we will examine the experimental results from this manifold and determine any quantitative functional performance benefits from moving from a machined manifold to an additively manufactured manifold.

About The MTC – The Manufacturing Technology Centre

The Manufacturing Technology Centre (MTC) was established in 2010 as an independent Research & Technology Organisation (RTO) with the objective of bridging the gap between academia and industry. They focus on delivering bespoke manufacturing system solutions for their customers and operate some of the most advanced manufacturing equipment in the world. They employ a team of highly skilled engineers, many of whom are leading experts in their field. This creates a high-quality environment for the development and demonstration of new processes and technologies on an industrial scale.

The MTC is part of the High-Value Manufacturing Catapult which is supported by Innovate UK.

This work was carried out as part of DRAMA. DRAMA was led by UK’s National Centre for Additive Manufacturing in partnership with leading technology providers, research organisations and the Midlands Aerospace Alliance – ncam.the-mtc.org/drama/partners. DRAMA was funded by UK Research and Innovation through the Industrial Strategy Challenge Fund and was supported by the Aerospace Technology Institute.

About the UK National Centre for Additive Manufacturing (NCAM)

The UK National Centre for Additive Manufacturing (NCAM) was created to accelerate the uptake of Additive Manufacturing (AM) by developing the technology and systems required to address the key challenges within the AM value chain. NCAM is based at the Manufacturing Technology Centre (MTC), part of the High Value Manufacturing Catapult. It is also home to The European Space Agency (ESA) AM Benchmarking Centre and a founding partner of the ASTM AM Center of Excellence.

NCAM has a team of engineers and technical specialists focused on AM who are ready to answer questions on all aspects of AM. Their facilities comprise metal, ceramic and polymer printers, plus a wide range of equipment for post-processing, and their new AM SmartSpace has the latest software available to help you de-risk your adoption of AM.