Taking a holistic approach

Decisions made by design engineers lock in materials, manufacturing and disposal processes, often inadvertently embedding hidden CO2 in to a product. Justin Cunningham discovers the tools that have been developed to give life cycle information from the outset.

It is a vexing issue for engineers, trying to be 'greener'. It is never quite as simple as using 'bio' materials or designing for more efficient use. While on the surface some products seem to tick all the boxes, drill down a little further and consider the whole system from cradle to grave, and it is not quite as good as first hoped, or anticipated. It is a source of frustration.

Bio plastic is one such example. This is often made from corn turned into a polylactic acid, a new type of polymer. However, this pushes up the price of corn and funnels supply away from the food chain. Additionally this bio plastic is more expensive, less durable and cannot be recycled.

Additionally, aluminium used in cars to make lighter structures might result in more miles per gallon, but aluminium is incredibly energy intensive to refine, as well as being difficult to join and recycle. The same can be true of some hybrid cars. The manufacture and materials used to make them can be more environmentally taxing than a normal car which negates a proportion of any in service fuel saving. It is a complicated, messy problem, which everyone still has a lot to learn about.

Perhaps the best example comes from Sarah Krasley, sustainable manufacturing manager at Autodesk. She says: "We can all agree lead is not a very benign material. As a result, NASA decided to swap a lead solder in favour of a tin solder on a satellite and put it in to orbit. But the satellite did not perform as well as it would have if lead had been used and, because of that, the entire satellite had to be decommissioned, brought back down to Earth, and dealt with at a cost of hundreds of thousands of dollars and tons of waste.

"What that illustrates is the idea of looking at a material in context. Is that material going to require less energy or water, or require fewer processes to form in to the component that you want in your assembly? And will it perform well?"

Like many of the large CAD vendors Autodesk wants to bring this information to designers so they can make informed decisions early in the design process. It has teamed up with Cambridge based Granta Design to provide detailed information about some 3,000 different materials. Autodesk hopes this will give the opportunity for design engineers to experiment with different materials and virtually simulate and test them to see whether they may be more suitable for a given design.

Its EcoMaterials Advisor is designed to act as an advisory tool. It is not there to make the engineer choose one material over another, but to give information about embedded energy, CO2, water, whether it is RoHS compliant, and the end-of-life considerations such as whether it can it be recycled or only 'downcycled' (degradation of the mechanical properties when recycled). The aim is to allow engineers to make like-for-like comparisons at the front end of the design process and digitally compare their mechanical and environmental properties to find the most suitable balance.

The library also has added raw material cost information. Though this does give information on many non-traditional materials and give engineers a glimpse at some 'exotic' alternative materials, the key is to focus on 'traditional' materials.

"If you use a specific grade of vinyl, for example, you have the opportunity to experiment with different grades within that family," says Krasley. "So you may find that there are subtle nuances in processing, or impacts that you have not thought about that change the carbon footprint and how much energy it will take to produce.

"Even making subtle changes on an incremental level can scale to something pretty significant if you are dealing with a product line of a hundred thousand widgets."

Sustainability is the most recent phrase in a long list of buzzwords to describe engineering the lowest environmental impact with factors including embedded energy, CO2, water, and disposal. And Solidworks is also keen to incorporate a sustainable, whole system, approach in its CAD software.

"Sustainable design is much broader than just materials," says Asheen Phansey, SolidWorks' sustainability product manager. "It's a part of the story but the full product lifecycle has impacts in a lot of different ways and we usually talk about it in five or six stages."

These stages are raw material extraction, materials processing, parts manufacturing, assembly, product use, and end of life. Each section can be altered and therefore assessed at the design phase. Like Autodesk, Solidworks use a dashboard called 'Environmental Impact' which highlights the embedded carbon, air, energy and water in a design and further breaks this down in to a pie chart to show how this is distributed between material, transport, manufacturing and end of life. It can then compare different materials with a baseline to give the engineer a quick comparison.

"This is not replacing lifecycle assessments by any stretch," says Phansey. "It is giving upfront design guidance and acting as a filter."

Often, 'more sustainable' steps seem counter intuitive such as adding weight or material. But real world use and a holistic view reveal this can sometimes be the best thing to do.

"If you go and buy a carton of yoghurt from the store and the yoghurt lasts for a month and the container lasts 10,000 years; that's a little bit over-designed," says Phansey. "But if you decide to make it thinner and a pallet falls off a truck, ten of them break instead of one and you increase the spoilage across the supply chain, that means you need to grow more food to meet that increased surplus. This in turn will lead to more environmental impacts than if you made the wall a bit thicker. So it is a balance."

The CAD giants are all keen to encourage design engineers to take steps to lock in more sustainable materials. They are also keen to highlight that this is more than about being altruistic for future generations, but hard economics. If a material requires a lot of water or energy to produce, then it is likely going to get more expensive. Energy is for the most part finite and the more natural resources are depleted, the more expensive these materials are likely to become.

Krasley adds: "From a cost perspective you have got to deal with this stuff. There are going to be billions of new people in the world economy and if you don't have a proactive strategy for finding materials that are not impactful from a resource perspective, your cost of doing business is just going to go up."

Author
Justin Cunningham

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