Additive materials are slowly but surely starting to find their place in design

Additive manufacturing is a relatively new technology and, as with any new technology, there are challenges to unlocking its full potential. These include material development, machining processes, the software controlling it and of course, cost.

Of these, it is the approach to materials development that is currently receiving a great deal of attention. New alloy development could bring significant benefits both within the process itself and in the quality of the parts produced. The repeatability of the process will mean the work of the designer will be much easier since it will be less vulnerable to changes in geometry, resulting in better material properties.

With alloy development, at some point with computer modelling and additive manufacturing, a time may be reached where an alloy can be developed specifically for an application. This will make it possible to develop a bespoke alloy for that particular product. But that is the future, the present is a little different.

Dr Rob Sharman, global head of additive manufacturing at GKN Aerospace says: “Fundamentally, the challenge with additive manufacturing is that you are creating the material within the same process as manufacturing a product. Within aerospace, we focus mainly on titanium and nickel alloys.

“The raw materials are aligned with the industries being supplied, which is why we are using metals familiar to aerospace construction and why other companies are using different alloys that are more suited to different types of product.”

As Sharman goes on to explain, GKN is not changing the chemistry of the materials used in additive manufacturing, rather it is changing their properties.

Cost is always a challenge in the development of any technology. It is no different with changes in additive manufacturing, but it does require a different approach to how developments occur. In the automotive sector for example, material development has traditionally meant moving from steel to aluminium, but additive manufacturing doesn’t necessarily follow this pattern.

“Additive manufacturing requires a complete reset of how people think about manufacturing. GKN hasn’t changed the raw material supply of titanium and nickel alloys, the focus for our processes is about affecting the microstructures of the materials and using the results for innovative applications,” says Sharman.

This is a point of view shared by Henry Greenhalgh, senior engineer at HiETA Technologies, who says: “Tailoring the micro-structure within a component so that you get material properties that are all different by design is an exciting idea that has already been worked on.

“It’s on a microscopic scale, changing the distribution of different phases within the alloy and the grain sizes within the alloy to achieve different properties,” he says.

How successful firms are in integrating this microscopic approach will inevitably come down to cost. No technology is free, after all. But while work continues on that approach, a sub-genre of material is being used with increasing frequency: lattice structures.

Greenhalgh says that on a larger scale, lattice structures give firms similar benefits to changing the micro-structure of materials. “I think as additive manufacturing comes down in cost and it becomes easier to produce things using it, it becomes more repeatable and we’ll see lattice structures more,” he adds.

Much of it comes down to the maturity of the industry and technology, as additive manufacturing is still relatively new, and how different areas – material, manufacturing and software – interact.

Greenhalgh is keen to mention the software, saying: “On the design side, there is CAD analysis software out there that is developing with the technology, allowing designers to get the most out of additive manufacturing, and lattice structures are a good example of that.”

“It has been quite difficult to build lattice structures. The CAD and analysis software couldn’t cope with it before, but that is changing and it’s becoming easier to use,” he says.

GKN’s Sharman has also seen the increased development and use of lattice structures, and anticipates their use increasing. “At the moment, additive manufacturing is being used in a variety of applications to produce lattice structures at a much lower cost than with previous-generation technologies,” he says.

“Future applications could involve using lattices where it was previously not possible from either a cost or engineering perspective, for example in lightweight structures or for energy absorption and acoustic attenuation,” he continues.

The future of additive manufacturing and material use is looking promising. Not only will machine and software improvements help move the technology forward, so too will new types of alloy and the possibility of the use of composite and multi-materials. All of which could help additive manufacturing achieve a greater level of usage in a variety of industries.

According to Greenhalgh: “New alloy development will make a big difference, but I think the machine and software improvements will have a huge effect. On the machine side I think the cost and repeatability will be key; repeatability will come from in-process monitoring, which will mean you will get the same result every time and you’ll know exactly what you’re getting throughout the process.

“I also think there will be similar improvements on the software side where you get modelling techniques that allow you to understand what properties you’re going to get out of the material, or different parts, and you’ll be able to influence that design.”

At GKN, research is focusing on composite and multi-material manufacturing processes. “GKN is in the early stages of investing in composite additive manufacturing processes, and there are potential applications for this across both aerospace and automotive. Multi-material processes are also at the research stage, as we develop systems and identify target applications for this kind of offer,” says Sharman.

Whether the final application is aerospace, automotive, medical or fashion, the developments in additive manufacturing could have wide-ranging benefits, but there are still many challenges to overcome. Improvements are being made, and as with all developments, it is a gradual process, but as manufacturing, software and material technologies advance, those benefits will be realised.