The Energy Implications Of Additive Manufacturing

Additive Manufacturing (AM) is a three-step process involving Computer Aided Design (CAD), creation of a digital computer file and then manufacture of a product from the computer file using 3D printing.

According to the latest Wohlers Report, the AM industry grew by 33.5% last year to $9.975 billion. The number of producers of larger AM systems - priced at over $5,000 - grew to 177, up from 135 in 2017 and 97 in 2016, with a clear shift away from desktop 3D printing systems to industrial system manufacturers.

But perhaps most significant amongst the report's findings is that end-use applications have become the largest single use of AM technology, overtaking functional prototyping. In other words, the use of AM in mass manufacturing is growing, which is where it will start to have an impact on energy demand, both in terms of transport and industrial energy use.

Forecasting uncertainty

Forecasts of exactly what impact AM might have on energy demand and how soon vary widely, not least between disciplines.

Market intelligence company IDC forecast in 2016 that worldwide spending on 3D printing would reach $26.7 billion in 2019. IDC's forecast in January predicted spending this year of $13.8 billion, half of the forecast made just three years earlier.

In its publication '2015 commercial transportation trends', consultants PwC forecast that up to 37% of global ocean container business was at risk from AM.

ING bank, in 2017, using a scenario approach, estimated that AM could reduce world trade by almost 25% by 2060, or by as much as 40% by 2040, as a result primarily of the localisation of manufacturing. This outcome, or even direction of travel, would have huge implications for energy demand for transport.

However, other studies of supply chain development are much more cautious, and as IDC's forecasts show, AM proliferation is proving slower than expected.

Moreover, energy demand analyses see light-weighting and transport efficiency rather than changed supply chains and reduced transport volumes as the primary factors behind AM's impact on energy demand.

Energy impacts

AM certainly has disruptive qualities. Unlike conventional subtractive techniques, it only uses material where it is required, so it uses less. In addition, surplus material - usually metal and polymer powders - can be recycled and re-used, meaning no or very little waste. Greater control over the micro structure of the component material can also result in the discovery of new material properties.

For single components reduced materials impact can be dramatic. For example, a 2018 study, Energy Consumption in Additive Manufacturing of Metal Parts, found that the buy-to-fly ratio (the ratio of material bought to produce a component to the material in the component when finished) for conventional machining of an aircraft bracket was reduced by AM from 8:1 to 1.5:1. It also found that as a result of reduced materials use the energy consumed in manufacturing the product by AM was lower than the conventional process.

The creation of a component in one step also means reduced assembly, cutting the need for multiple parts, joining parts, additional machinery, labour and transport of semi-finished goods.

However, the biggest energy saving from AM was from end-use efficiency. Light-weighting in the aerospace and auto industries means long-term energy use savings throughout product life as a result of better fuel efficiency, a factor that applies both to internal combustion engines and electric battery performance.

A 2016 study conducted by Germany's Fraunhofer Institute, Quantifying the overall impact of additive manufacturing on energy demand concluded that while the energy consumption of both processes for pre-product production were similar, energy savings resulted from AM in both the production and utilisation phases.

Scaling these savings up to national level for cars resulted in non-negligible gains for a single AM produced component, owing to light-weighting.

Researchers at the Netherlands' Delft University of Technology in 2018 published a study, The effect of additive manufacturing on global energy demand, which outlined four scenarios with different rates of AM adoption. This estimated potential energy savings of 5%-27% of global energy demand in 2050.

The study suggested savings of 5-25% in the aerospace sector and 4-21% in construction. For aerospace, the largest component of the projected energy savings again came from the impact of light weighting in end-use applications. In the construction sector, the benefits were more evenly spread across lower material use and thus less transportation requirements, as well as greater end use efficiency.

Manufacturing uncertainties

Certain types of product are clearly more applicable to AM, which is another way of saying that AM remains limited to niche production processes. It is also limited in materials, using predominantly metals and polymers but not natural materials, even if the digital capabilities of CAD suggest more and more metal/polymer applications will be found.

AM's advantages in prototype design are well established, but when it comes to manufacturing its advantages are largest when the product has a complex geometry; when a relatively short production run is required; and when light-weighting has a direct impact on both the production and operating costs of the end product. An additional advantage is the potential for 'mass customisation'.

For these reasons, both aerospace and auto manufacturers have been early AM adopters, moving in some cases to industrial AM production of components. Medical applications are another strong area for AM. The technology has, for example, revolutionised the production of hearing aids, which need individual customisation and have complex geometry.

Supply chains

However, it is less clear that AM will have the radical impact on manufacturing supply chains that forms the basis of some of the technology's more disruptive forecasts. The idea is that manufacturing moves closer to demand and is produced on demand, allowing retailers to order on the basis of sales, rather than what they think they will sell, thereby cutting inventory, wastage and transport demand.

However, while mass customisation appears an attractive concept in terms of meeting customer demand, it can be achieved at the end of a longer, slower supply chain that still reflects the multiple factors determining the siting of manufacturing and assembly plants.

Moreover, successful AM products will be those with a high sensitivity to transport costs, which puts AM processes in competition with containerisation. Containerisation has been a huge factor in reducing transportation costs, allowing the development of global supply chains and trade between countries and regions more generally. The cheaper transport is the more other factors - such as labour costs and cheap energy supplies - will remain the decisive factors for siting manufacturing plant.

AM is clearly a technology with disruption potential, but despite being invented more than 30 years ago, it is still developing relatively slowly, albeit increasingly aided by the wider digitalisation of manufacturing production processes and supply chains. For the moment, its design capabilities look likely to have more impact on energy demand than its ability to reshape supply chains and global trade flows.