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Stewart Williams

Cranfield University

New Wire Additive Manufacture (NEWAM)

Metal additive manufacture (AM) techniques are categorised based upon the form of the material (powder or wire), the heat source (laser, electron beam, or electric arc) and how the material is delivered (pre-placed bed, or direct feed). Each technology has particular properties suited for specific applications. For example, powder bed fusion yields precise, net-shape components that can be very complex in design. However the size is limited, cost high and build rates are low. In contrast, Directed Energy Deposition (DED) processes can build near-net-shape parts at many kilograms per hour with any size; e.g. a 6 m long aluminium aero-structure was produced at Cranfield University in a few days. Wire based DED AM has proven capability to make large titanium parts in a timely manner with much reduced cost, resulting in tremendous industry pull. However there are still some major challenges and opportunities in wire based DED AM.

• Currently systems for wire based DED use commercial off the shelf equipment and materials. This leads to significant limitations; a trade-off between build rate and deposition accuracy, non-optimum material properties due to the mismatch between material composition and thermal profiles

• How to guarantee full structural integrity of as built components.

• A great deal of empirical know-how is required for every new application, leading to long lead times and high costs. A full science-based understanding of DED processing is needed to exploit its full potential and ensure widespread industrial adoption.

To tackle these challenges and opportunities EPSRC has funded a Programme Grant, led by Cranfield University; New Wire Additive Manufacture (NEWAM). The programme started in June 2018 and has three other University partners; Manchester, Strathclyde and Coventry.

The challenges for NEWAM are:

• New innovative high build rate metal wire AM processes and systems for net shape deposition at low cost over large volumes with homogeneous microstructure and properties – target 8kg/hr net shape for Ti64

• To build robust physics-based process and materials’ models that give detailed process understanding, to enable more rapid process development and provide algorithms for in-process microstructure control

• Design of new materials and alloys, tailored to both existing and new deposition processes, giving performance better than the equivalent wrought alloys currently used

• To ensure guaranteed as-built structural integrity with process-independent physics-based quality control and assurance enabling low cost industrial qualification

This talk will outline how these challenges will be addressed, the roles of the individual Universities and progress to date.

Biography

Stewart Williams has a PhD in laser physics from London University. After spending five years at Edinburgh Instruments developing lasers and laser systems he moved to the Advanced Technology Centre of BAE Systems. Here he ran a group whose main area of research was laser processing of aerospace materials including welding, cutting, drilling, micromachining and surface treatments.

Currently he is Director of the Welding Engineering and Laser Processing Centre (WELP) at Cranfield University. Current research interests are pioneering wire based DED AM processes for large engineering structures and laser based material processing in areas such as laser hybrid and micro welding and surface treatments.

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