Features


Sheffield’s Mercury Centre. Created with the assistance of the European Regional Development Fund (ERDF) the Mercury Centre is dedicated to providing industry with access to the latest advanced manufacturing techniques. Their main focus is powder-based manufacturing, creating complex products with enhanced resource efficiency using processes such as metal injection moulding, spark plasma sintering and ALM.


The technique chosen for the production of the trophy is Arcam electron beam melting. This ALM process involves building up a component, layer-by-layer using a 3kW electron beam (e-beam) to melt shapes in a bed of titanium powder. A 70 micron thick layer is deposited on the powder bed which is then preheated with the e-beam to around 730°C to raise the temperature of the powder with the aim of reducing residual stresses and subsequent distortions in the final component. Then a higher powered e-beam is used to accurately melt the powder to create the net shape for that layer. The table is then lowered by 70 microns and the process repeated until the design is complete. The process is carried out in a vacuum as titanium is a highly reactive metal which would produce degrade properties or potentially combust if oxygen were present.


After the component has cooled,


it is placed in a chamber and is blasted with compressed air to displace all the un-melted metal powder, revealing the final fully dense component. The displaced powder is then sieved to remove agglomerates and re- used for the next build. The working area inside this Arcam machine is 200mm by 200mm by 350mm high, and therefore larger components can be made separately and joined together in an electron beam welding unit. The beam is extremely precise, resulting in minimal production of heat affected zones, so are ideal for high end applications.


E-beam ALM can currently be used to form metal products using titanium (alloys and aluminides), copper, aluminium, stainless steel, niobium, beryllium, cobalt-chrome alloys, nickel based super alloys, and tool steel. However, the prices of these metal powders vary and can often be expensive due to the high purity production methods. The trophy will be fabricated from titanium (Ti6AL4V), which currently costs around £200 per kilo. Although this powder feedstock may be more expensive than a sheet of metal or billet, its utilisation is significantly higher, often over 95%, unlike traditional forming methods where material wasted in the form of machining swarf, casting sprus and forging clippings can amount to just 10% of the feedstock ending up in the final component. Near net shaping using ALM is a lengthy


process for each part, however, no expensive tooling is required and it allows for a greater degree of design freedom creating geometries that would be impossible to make by other means. Furthermore, due to the reduced amount of time that it takes to get from initial design to final product, the process is the epitome of rapid manufacturing.


ALM can be used to manufacture products from different industries including aerospace, automotive, biomedical, rail and energy. With E-beam ALM, the as-built surface roughness can be quite high, however, this can be a desirable feature e.g. for the stem of a hip replacement where bone in- growth is encouraged by the rough finish. If a smooth surface is required, allowances are built into the part to be able to polish back to the desired finish. Moreover, the components produced have been proven to show properties better than those of cast materials and comparable to wrought products, but with a considerable reduction in weight afforded by design freedom. Subsequently, the centre has received interest in the process for the fabrication of aerospace and Formula One car parts, as well as high value consumer electrical goods.


With the backing of the ERDF funding, The Mercury Centre is able to help businesses in the region to optimise their manufacturing processes and try out these new technologies.


They also provide support to those who are considering purchasing their own ALM machines and are seeking practical transferrable advice.


The winners of the Harvey Flower prize and the trophy design competition will be announced soon.


For further information, please contact Kathryn Jackson at: Kathryn.Jackson @namtec.co.uk


E-mail: info@namtec.co.uk Tel: +44(0)1709 724990 www.namtec.co.uk 13


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