Why design for AM must progress

25 June 2018

Ahead of this year’s Additive International summit, the University of Nottingham’s Professor Christopher Tuck discusses how design for additive manufacturing must adapt for new materials and methodologies

As additive manufacturing technology continues to evolve, we are seeing new materials being developed and more complex, higher functioning components being produced. These changes mean that more traditional design for additive manufacturing (DfAM) processes, such as topology optimisation, can come up short.

Achieving optimal components is not impossible with topology optimisation, but AM’s design constraints need to be considered and accounted for, or the process and materials will start to impinge on the design, rendering it unachievable.

For this reason, we’re seeing the industry move toward more specialised DfAM methodologies that are specific to techniques and systems such as selective laser melting (SLM) or laser powder bed fusion (LPBF)-driven machines.

Designers and manufacturers working with AM recognise that the specificity of the process, or even the machine itself, can be a key factor to a successful build and are starting to incorporate this more and more into their topology optimisation and DfAM strategies to yield the best results.

Balancing efficiency and complexity

DfAM isn’t always about building bespoke parts, however. It is more about being able to build something complex and reliable.

Efficiency and cost effectiveness play a key role and often trump the need for bespoke, optimised parts.

Achieving this requires a balance between design and efficiency. Companies such as Thales Alenia Space, for example, are using topology optimisation together with Laser Beam Melting (LBM).

Florence Montredon, Thales’ AM technologies development manager, will be discussing in her presentation at Additive International how this has helped the company open doors to new design opportunities and create more complex and efficient shapes with better weight distribution.

Designing for serial production

Another factor contributing to the evolution of DfAM is that of serial production. There is a general understanding that serial production will result in less functionality, but given the cost savings it promises, it is still an attractive option.

As more organisations are striving to achieve this, they are looking at economies of scale and how these affect the design process. We need to be asking questions such as, ‘How does serial production affect the build envelope packing?’.

Solving the post-processing issue

Minimising the manual intervention required in post-processing is by no means a new issue, but as more people start to investigate the idea of serial production, it is becoming an increasing factor to take into account at the design stage of AM projects.

Six business-led AM project teams will present their work to streamline post-production at the preconference ‘Business Innovation in AM’ day.

One of these teams, for example, will speak about its experience of developing an automated production cell, in which a robot receives an AMproduced part and then passes that part through a series of automated finishing processes, all based on software instructions that the robot receives directly from the component’s design specifications.

This innovation ensures that the required finishing processes are properly considered from the start at the component design stage, removing the need for costly manual post-processing.

DfAM for new and multi-materials

Looking into the realms of research, conventional CAD methods no longer apply. Instead, we are seeing people designing materials for specific processes.

At this early development stage, efficiency is not a key driver and methods like voxel-based jetting are used to produce multi-materials within the same machine.

These are still a long way off from being commercially available, but will no doubt contribute to the further evolution of DfAM. Virginia Tech’s Christopher Williams will be exploring the ‘concurrent design of materials and additive manufacturing processes’ in his conference presentation.

He recognises that in order to create products that satisfy multiple functions and design objectives, AM processes need to advance further in material selection and process capability.

Williams will discuss how the concurrent design of the material and the AM process can enable the expansion of the catalogue of AM materials as well as its capabilities.

He’ll look at the likes of nano-inks as structural binders, low-temperature soluble polymers for material extrusion of pharmaceuticals, and fully aromatic polyimides via vat photopolymerisation.

Like AM itself, design for AM is continually evolving. Factors like speed and efficiency are driving the design stage more than ever, paving the way for serial production and changing the face of DfAM from more bespoke parts to complex, reliable and cost- effective ones.

As materials become more advanced, design technologies will follow suit and – further down the line – when multi-material AM becomes a commercial reality, the DfAM methodologies of today will likely be rendered obsolete, or at least unrecognisable.

International (formerly the International Conference on Additive Manufacturing & 3D Printing) takes place at the Nottingham Belfry hotel on 11-12 July with the pre-conference day on 10 July. To register visiit additiveinternational.com

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