Additive manufacturing: the next layer

Additive manufacturing has gone beyond being a revolutionary process and is now firmly in the mainstream. Which begs the question, what does the future hold and where are the gains to be made for manufacturers who have still to embrace the technology?

In this special focus, The Manufacturer looks at some routine and unusual ways in which additive manufacturing is being deployed, but first Nick Peters set out to get a glimpse of the future at the Centre for Additive Manufacturing at the University of Nottingham.

Experimental multimaterial 3D printing of silver electronic circuity - image courtesy of CFAM.
Experimental multimaterial 3D printing of silver electronic circuity – image courtesy of CFAM.

The existence of the Centre for Additive Manufacturing (CFAM) is a triumph for enlightened government and industrial backing for advanced R&D. It is part of a wider innovative manufacturing research programme run by the government-backed Engineering and Physical Sciences Research Council (EPSRC).

It has attracted more than £24m in funding from a wide variety of stakeholders, mainly the EPSRC and over 50 industrial partners, with significant input from the University of Nottingham, which is demonstrating its commitment by building a new £25m research centre on campus that will house the CFAM and three other research departments from 2018 onwards.

The CFAM is internationally regarded as the top additive manufacturing (AM) research facility in the world. For the past 15 years, under the direction of Professor Richard Hague, it has consistently pushed the boundaries of research into areas that make today’s often startling industrial applications of AM seem commonplace.

The 100-strong team are developing new printing technologies, new processes and experimenting with materials down to the nanometre scale, creating possibilities that are, as we shall see, as mind-blowing as they are apparently limitless.

This article first appeared in the October issue of The Manufacturer magazine. To subscribe, please click here.

Where we are

Additive manufacturing using polymers or metals has added a whole new dimension to manufacturing. Polymer 3D printing is almost ready for mass production, such are the advances in speed and volume being made.

The University of Nottingham is building a new £25m research centre on campus that will house the CFAM, among other research departments.
The University of Nottingham is building a new £25m research centre on campus that will house the CFAM, among other research departments.

As we have reported in previous articles on companies such as BAE Systems and Meggitt, AM-printed metal parts are replacing conventionally-manufactured ones in ways that improve weight, volume and, where applicable, liquid or gas flow.

We’ve seen examples of aircraft brackets and jet thrust bleed valves. Inevitably, given the greater complexity of printing in metal, mass production will be some way off, but it is already at the stage where companies that produce short-run, high-value products, such as luxury carmakers, can create low-volume parts using AM.

Additive manufacturing is therefore not only here to stay, but if it is not yet on your radar, it should be.

“People who aren’t using additive techniques such as 3D CAD, and digital additive techniques for rapid prototyping, are doomed,” Professor Hague told me. “They’re really in trouble.”

Perhaps part of the problem when it comes to resistance to take-up of AM technology lies in the hype around additive that highlights fantastical, organic-looking products that resemble bone or lattice structures.

These are topologyoptimised examples of what metal printing can achieve, but they are not what mainstream manufacturers necessarily want, and in rejecting the concept on the basis of these exotic shapes, they may be rejecting the elements of 3D printing that can really help them, such as prototyping with polymer 3D printing.

“The difference between prototyping and additive manufacturing,” Hague continued, “is that if you’re doing rapid prototyping, but you’re going to manufacture it conventionally, you have to design it conventionally.

“So, the key thing is changing the design to suit the manufacturing process. It may well not be cost effective to additively manufacture a conventional design.”

A lightweight aluminium structure with a triply periodic minimal surface (TPMS) lattice - image courtesy of CFAM.
A lightweight aluminium structure with a triply periodic minimal surface (TPMS) lattice – image courtesy of CFAM.

The CFAM team have already addressed this by creating topologyoptimised structures that still manage to emulate conventionally designed products. Hague showed me two versions of a diesel pump.

They looked almost identical, but for the fact that the 3D-printed one had inlet and outlet nozzles already printed onto it and, most importantly, the casing was actually a complex-lattice, poly-optimised structure with a smooth metal coating that made it look very similar to the machined-original but at less than half the weight.

It is up to designers to recognise the tremendous advantages that this holds in terms of weight and functionality. Perhaps, I suggested, designers might hold the keys to the additive kingdom.

“That is actually key,” he said. “I might get in trouble with my colleagues for saying this, but if you’re not adopting the design freedom of additive, there’s no point in doing this. You absolutely need the design potential before additive manufacturing makes sense.

“There’s no point in additive manufacturing something that you can produce conventionally, in my view. But if you really explore the design freedoms, you can produce these poly-optimised parts, these complex lattice structures.”

Again, commercially-available technology currently only allows for short-run printing of parts like this, but the speed of development is such that that could change, and, as always, those who have the capacity to adapt will be ahead of the pack.

Where we are going

“CFAM is science based but industrially driven,” Richard Hague stresses. If it were the other way around, then his team wouldn’t be out there on the very farthest reaches of possibility, trying to do things with materials that have never been done before.

Imagine a prosthesis that has all the circuitry and internal drive mechanisms printed inside - image courtesy of CFAM.
Imagine a prosthesis that has all the circuitry and internal drive mechanisms printed inside – image courtesy of CFAM.

“We’re now in a process of looking at next-generation multifunctional additive manufacturing. How do you design for that? How do you process multi-materials in the same build? How do you functionalise that? How do you combine materials that have different chemistry, physical states, and different levels of compatibility, and temperatures of processing? It’s complex work!”

Multi-material additive manufacturing adds a whole new dimension to AM. It’s tempting to call it 4D printing. It means being able to create, in one go, a single product containing different materials, such as polymers and metal.

That means, for instance, being able to 3D print electronic circuitry that is embedded into the system it is driving, not attached to it. Imagine a prosthesis that has all the circuitry and internal drive mechanisms printed inside.

Crucial to that will be the ability to jet-print metal in the same way that an ink-jet printer operates. (Currently, metal printing is done using lasers or ion-beams and metal powder.) It is enormously difficult because of the melting point of metals, but the CFAM is actually doing it, as Hague showed me in one of the experimental areas of the laboratory.

“It is a way of selectively depositing high-temperature metallics,” he told me. “What you’re seeing here, in this room, is an internationally unique facility. No one else in the world has one of these.”

I examined the product from this machine, developed in collaboration with Canon Océ in Holland. At first blush, there is not a lot to see, but using a loupe I saw the tiny little droplets of metal deposited by the print head.

Measuring the surface texture of metal AM parts by X-ray computed tomography - image courtesy of CFAM.
Measuring the surface texture of metal AM parts by X-ray computed tomography – image courtesy of CFAM.

It is enormously hard to achieve. The most common conductive material in electrical and electronic systems, copper, does not print well, so the team is experimenting with silver. But that is just the beginning of the challenges.

If you’re printing in multiple materials, you need multiple print heads. CFAM has a twin-head and a six-head machine. Once that has been achieved, there are other issues. Polymers are tough to jet print, so now the lab is working on a way of printing a layer of monomer, then a layer of catalyst, one on the other, so they interact to become polymers.

And there is more complexity yet

“Getting dissimilar materials to coalesce is very hard,” Hague said. “If you’re depositing nanoparticulate silver or copper, or whatever metallic you’re depositing, you might have an interface, a barrier, that means you don’t get the conduction you want, so what’s the point? You have to overcome that.

“Some materials interface very well, and some materials will blend with each other, and some will have a very, very clear barrier between each other. Sometimes you will want a barrier, sometimes you’ll want them to merge, and sometimes you’ll want them to do something different.

“When you’re getting down to the voxel level [a voxel is a three-dimensional, volumetric pixel] and you’re interrogating the voxel-by-voxel deposition of individual droplets of materials, it’s very difficult.”

Hague then showed me an even more extraordinary set of experiments – or rather, he described them, because they are experimenting with printing at the nano-level using two- or multi-photon lithography and therefore impossible to see with the naked eye.

Multi-photon lithography in itself is not necessarily new, but the materials and techniques they are using, including photo-reduction of salts to create ultra-tiny new metal composites is way ahead of anyone else.

Professor Richard Hague, director of the Centre for Additive Manufacturing, Nottingham University.
Professor Richard Hague, director of the Centre for Additive Manufacturing, Nottingham University.

“We’re thinking of this mainly in the sensing domain, making little sensors that we can either inject or put onto other bodies, that we can print using two-photon lithography on top of the other parts. It could conceivably have medical as well as industrial application.”

Much of the work being done by Richard Hague and his team at the CFAM is so far in the experimental future that it will be years before it has commercial application. It is possible, however, for manufacturers to access the Centre’s expertise through its spin-out company, Added Scientific Ltd. Here they can learn about the very latest design tools, materials and printing techniques that are practical and deliverable in today’s market.

It’s a 3D world out there

Additive techniques are changing manufacturing across the board. Here are three case studies that demonstrate the extraordinary versatility of 3D printing.

3D delivering speed

Engineering in F1 racing has been completely changed by additive manufacturing. The Renault F1 team creates 600 parts every week during the season, using a suite of 3D Systems printers, including six stereolithography (SLA) and three selective laser sintering (SLS) machines.

Renault’s 2027 concept racing car is able to achieve double the power-to-weight ratio of current F1 models by extensive use of 3D printed parts, including a lightweight honeycomb composite cockpit - image courtesy of Renault.
Renault’s 2027 concept racing car is able to achieve double the power-to-weight ratio of current F1 models by extensive use of 3D printed parts, including a lightweight honeycomb composite cockpit – image courtesy of Renault.

This enables the engineering team to adapt a car to the most minute variations it encounters on different circuits across the world.

“The car is evolving daily during racing season,” says Patrick Warner, advanced digital manufacturing manager at Renault Sport F1. “We require different components at every track, so making them with no tooling involved is obviously ideal for us.”

The critically important use of AM comes in wind tunnel testing. “The car model in the wind tunnel features a complex network of pressure sensors,” says Warner. “Before SLA technologies were available, these were positioned by drilling pressure tappings into metal and carbon fibre components.

“The ability we now have to produce complex solids with intricate internal channels has revolutionised our ability to place these sensors and increase their numbers. It’s an aerodynamicist’s dream come true. We couldn’t come close to doing that conventionally. We’d need a machine shop the size of a small city.

“This gives us a one stop shop. We have the equipment we require, the materials we require, and the expertise we require from application engineers who provide us with service instantly.”

3D icing on the cake

3D printing is now making inroads into the food industry - image courtesy of CSM.
3D printing is now making inroads into the food industry – image courtesy of CSM.

3D printing is now making inroads into the food industry. CSM, one of the largest suppliers of baking ingredients, products and services in the world, announced this August that it is  working with 3D Systems to take 3D baking mainstream.

3D on the eco-trail

Rivertrace Engineering used rapid prototyping to radically speed up their services. It specialises in oil and water monitoring instrumentation for the marine and industrial sectors, with operations in mainland Europe, North America, the Middle and Far East.

Its sophisticated technology analyses contamination levels to ensure that water pumped back into the sea from rigs, power stations and ships is oil-free. Successful R&D is crucial for developing such high-end environmental protection technology.

Rivertrace’s legacy R&D operation comprised the conceptual design of a prototype, sending the drawings to a machine shop or toolmaker where the prototype was created, and then delivered to Rivertrace. This prototype was then integrated into the relevant product for performance testing.

After testing, the prototype design was revised and sent back for another prototype part to be machined and returned. This process could involve between two and five iterations, dependent upon complexity, to get the prototype to a production-ready part. It could take upwards of six weeks for each iteration of the prototype to be delivered.

Rivertrace’s owner, Mike Coomber, realised a change was essential, and brought in Canon to develop an on-site, rapid prototyping system using 3D printing.

“We had to optimise our R&D to better support our customers in achieving a greater level of sustainability,” he says. “It has transformed our R&D. We queue up the printer in the evening, and the following morning we arrive, clean the 3D-printed part and simply fit it to the product.

“We no longer have to wait weeks for parts and can get to the Proof of Concept in a few days and send updated drawings to our suppliers for production quantities. The impact on time, cost and efficiency is monumental, while at the same time allowing us to become a much more sustainable business because of it.”