Saturday, 26 July 2014
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Additive attractions

Manufacturing processes that print functional components offer a number of sustainability benefits, writes Dr Phil Reeves

Environmental sustainability is rapidly becoming an important consideration within supply chains, from minimising raw material consumption, water and electricity, to reducing waste stream and transportation distances. These efficiency gains are driven largely by production economics, as raw material and energy prices soar, water becomes scarcer and taxation on industrial waste climbs higher. It is this shift in thinking that could make additive manufacturing an attractive production proposition in the future.

Part time:material-efficient production

Part time:material-efficient production

Additive manufacturing covers a range of technologies that use a layer-by-layer approach to ’build’ end-use components from 3D CAD data. Applications include medical implants, consumer goods and a growing number of uses in the automotive and aerospace sectors. It is seen by many as an expensive alternative, where the additional cost of production often outweighs the benefits of low-volume, tool-less manufacture. But with growing environmental pressures, this could all be about to change.

The sustainable benefits of additive manufacturing have been postulated by academics, vendors and end users. However, we have recently seen a concerted effort to put some scientific data behind these claims. As discrete technologies, we know that most additive manufacturing processes are far from sustainable as they consume a large amount of electrical energy per unit volume of product. However, this is largely irrelevant in the global sustainability debate, as it is the lifecycle of the product that matters to the global environment, not just the discrete production step.

“Additive manufacture can mitigate the need for large amounts of raw material in the supply chain”

Additive manufacturing does in fact have a number of sustainable advantages, most notably the ability to mitigate the need for large amounts of raw material within the supply chain.

Although additive manufacturing produces waste material in the form of support structures, it is largely material efficient when compared with processes such as machining and casting. Because additive manufacturing processes use liquids, powders or filaments, only the raw material needed to produce a component is consumed during the production phase. This differs from CNC machining, where a billet of material is often machined down to a fraction of its original volume. Research as part of the Atkins project at Loughborough University has found that additive manufacturing processes can consume as little as five per cent of the raw material needed to produce an equivalent machined part. This is significant if we consider the relative scarcity of materials such as titanium, and the energy needed to extract and produce materials such as aluminium. The increased energy consumption of metallic additive manufacturing processes can, for some high buy-to-fly ratio parts, be largely offset by the savings in raw material embodied energy.

Another sustainable benefit of additive manufacturing is the ability to produce optimised geometries with near-perfect strength-to-weight ratios.

Weight plays a crucial role in vehicle emissions and is even more critical in aircraft. Research involving Boeing and Virgin Atlantic has shown that additive manufacturing could be used to reduce the weight of non-structural components, such as seats and entertainment units. However, this can only be achieved through component redesign for additive manufacturing, using topological optimisation algorithms or lattice structures, resulting in geometries that can only be manufactured using a layer-based approach.

To prove the benefits of switching to an additive approach, Atkins partner Econolyst has launched a beta version of Enlighten, a web-based software tool that allows users to model the economic and environmental sustainability of their supply chain at the product design stage. Enlighten enables users to analyse their 3D CAD data and build virtual supply chains using both additive and traditional processes. The tool allows users to compare designs, materials, processes and supply chain locations. It then models the impact of the part over its lifecycle, resulting in a carbon footprint, embodied energy and economic model.

Dr Phil Reeves is managing director of additive manufacturing consultancy Econolyst


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