Expert insight: Additive manufacturing

Professor Phill Dickens discusses the use and development of 3D printing – but warns not to believe the hype.

Phill Dickens, professor of manufacturing technology at the University of Nottingham, started work in rapid prototyping [3D printing] in 1990. In the early 1990s, he founded the Rapid Manufacturing Research Group (RMRG), leading various research projects and securing an international patent that is still being used. The first recipient of the International Freeform and Additive Manufacturing Excellence (FAME) Award in 2009, Professor Dickens is also founder and director of Added Scientific, a spin-out from the University of Nottingham that helps companies in the supply chain for additive manufacturing (AM) with technical assistance in developing materials and processes.

So what is AM?

It’s quite different from most other manufacturing processes in that we make parts by adding layers of material. Where other manufacturing processes take material and deform it or machine it away, we build up the material as we go along to get the final shape. The first commercial rapid prototyping machine was launched in 1987, so it’s been 30 years in the making.

There has been a lot of talk about AM, or 3D printing as it is frequently referred to, but is it delivering on its promise?

Some people say 3D printing is going to solve all our problems and we’re going to be doing everything by AM in the future. It has perhaps been hyped too much, but there is a lot to be gained by using the technology. It can eliminate tooling and give you greater flexibility over your design. It can produce shapes that would have been difficult or impossible in the past. It also presents the opportunity to change business models. In the pharmaceutical world, for example, we’re doing a lot of work at the university on printing pills. AM offers many opportunities, some on cost, some on lead time and some on design.

“We have an opportunity in the UK to exploit the capability within R&D, but we only have a small window of opportunity, maybe three or four years, to do this” There are various AM technologies available, but which offers the greatest opportunity?

It depends on the application. Probably the most advanced are either the vat photopolymerisation, in which liquid photopolymer in a vat is selectively cured [hardened] by light-activated polymerisation, or powder-bed fusion, where thermal energy selectively fuses regions of a powder bed using a laser or electron beam. The powder-fusion technology is probably used the most for manufacturing at the moment.

The focus appears to be on plastics right now, but is the technology moving on to other materials?

Metals tend to be more difficult because their operating processes are at a higher temperature, so you are building tensile overload. Having said that, the progress that has been made in metals in the past five to 10 years is phenomenal. People are now making metal parts in a range of industries, using these techniques for manufacturing.

Most current applications focus on prototype or low volume. Can you envisage AM moving into mass-market production?

I have no doubt about that at all. What we’re seeing now are companies that are attempting to manufacture using processes that were developed for rapid prototyping, but processes are coming about that are designed for manufacturing in high volumes. There’s a company called Photocentric that is undertaking some very interesting work in this area. Once those technologies [become more mainstream] then the economics will change and things will become more suited to high-volume manufacturing.

Why is AM so attractive?

AM gives companies the opportunity to go into low-volume, customised products and produce parts and products that have much greater performance. It also offers a reduction in cost and lead time, as well as real opportunities in terms of new products, new businesses and new ways for businesses to operate.

Are there any areas that AM is more suitable for than others?

There are various areas of industry that AM can offer an advantage in, such as prototyping, design freedom, customised products, high-value manufacturing and applied topology optimisation. In some situations, some of these will be irrelevant and in other situations one of them might be the only reason you’re using AM. It depends on individual products rather than companies.

What can be gained by applied topology optimisation?

Topology optimisation is where you take a design and add or remove material where it makes sense, normally to increase the strength-to-weight ratio. By doing that, you can reduce the weight of parts by about 50%. The best examples of topology optimisation are people. Take bone structure, for example, and the internal geometry of bones, which is highly optimised because we’ve gone through millions of years of optimising bone geometry. What we’re doing [with AM] is taking that principle and applying it to engineering parts.

What do people mean when they talk about ‘state of the art’ in AM?

One thing we really have to do in AM is switch from prototyping to manufacturing, and to do that we need machines designed for manufacturing. They need to be more automated, they need real online control and inspection, and they need to eliminate a lot of the post-processing we currently have to do.

We also need more simulation so we can predict what’s going to happen when we build a part because sometimes you plug in the process parameters, but the part that’s produced is not very good. It might have porosity, cracking or other faults. We need much more upfront simulation so we know it’s going to be right first time. That’s more important in additive manufacturing than conventional manufacturing because with conventional manufacturing you’re often looking at big numbers, maybe thousands or hundreds of thousands of parts, so you can afford to make the first 10 or 20 and sort out your process parameters. But with AM, we’re often only going to be making one so it must be right first time.

How strong is AM in the UK?

In terms of research, the UK is pretty strong, on a par with the US and Germany, but if you look at application, we’re quite a bit behind those two countries. When it comes to actually making money out of AM, I’d put the US quite a long way ahead of us at the moment, and we’re some way behind Germany.

We have an opportunity in the UK to exploit the capability within R&D, but we only have a small window of opportunity, maybe three or four years, to do this. If we haven’t caught up with the US or are well on the way to catching them up within the next three or four years, we’re going to have a serious problem.

What’s holding the UK back?

The short answer is a lack of skills. We simply don’t have the qualified workers to take advantage of the new technology that’s being developed. They’re not coming out of schools and not studying the right courses at university. There are moves to address that, but it will take at least four years, more likely seven, before we see the benefits. By that time it will be too late for the UK to take advantage of the technology.