3D printing – material wise to grain size

Materials World magazine
2 Jan 2014
The European Space Agency is testing the use of 3D printing to create a lunar base

Will additive layer manufacturing be used to print space stations from moon dust and hearing aids at our doctor’s surgery? Eoin Redahan found out at the 3D Printing and Additive Manufacturing Industrial Applications Summit, in London, UK.

The early days of the Internet are sometimes likened to the Wild West. It was a time for pioneers, frontiers and cowboys – a time where thieves slipped beyond the law’s grasp.

The Internet continues to flout many of the rules. Businesses are still struggling to figure out how it works for them, but at least it has been corralled into an uneasy order. 3D printing can be likened to the early Internet and Wild West. Regulations, materials and processes have not yet been specified. It will take time to arrange a complicated situation. Oh, and in the meantime, there is much money to be made as an outlaw.

A different plane
The aerospace industry embodies the challenges and limitations of the technology. On the one hand, lightweight components of increasing complexity can be created using additive layer manufacturing. Rainer Rauh, of the European Aeronautic Defence and Space Company in Leiden, the Netherlands, explains, ‘You put material in the machine and the next day you have all the parts ready. Designs can be used to create ideal aerospace parts that reduce weight by 40–50%.’

On the other hand, 3D printed components come with weighty baggage. Powder suppliers cannot guarantee consistent grain size. The lack of a stable qualification process has made companies less willing to use additive manufacturing in larger components. Rauh says, ‘When we repeat [printed] parts, some of them do not work. If we have 100 parts, 99 will work, but one will not.’ In a sector such as aerospace, 99 out of 100 just isn’t good enough.

Rainer adds, ‘We have to take care that the powder is always the same powder. We also have to qualify the machines and the suppliers. If a company makes a small change, we need to qualify that. Otherwise, we could lose aircraft certification.’

Find the dust and build the base
While 3D printed components may struggle with the demands of commercial-scale manufacturing, the industry excels in areas where bespoke parts are required, such as space flight.

Additive manufactured components are ideal for creating lightweight parts with small geometries, both of which are necessary in streamlined spacecraft. Tommaso Ghidini, of the European Space Agency, headquartered in Paris, explained how additive manufacturing is also being used to develop functionally graded materials. By marrying the properties of ceramics and metals, scientists are creating materials that can withstand extreme propulsive forces, temperatures and oxidation.

Ghidini also laid claim to the day’s most audacious application of 3D printing. ‘You could send an additive layer manufacturing machine to the moon,’ he said. ‘Use the dust on the moon to manufacture your base out there.’

Even though the idea of a moon dust facility is far-fetched, sending a 3D printing machine into space makes sense for several reasons. The machine would be extremely useful for repair work and, as Ghidini noted, materials built in space wouldn’t need fortification against the aggression of launch.

From laboratory to industry
For some in the oil and gas industry, the powdered material qualification process is too slow and limited. According to Lorenzo Lorenzi, of GE Oil and Gas, in Florence, Italy, ‘The need to develop new materials is pretty high. We need new grades of nickel-based materials and high-temperature resistant materials.’

The company is using additive manufacturing to make complex combustion chamber parts for gas turbines, such as fuel nozzle components. However, to use the material in more critical components, they need a quicker classification process. He says, ‘At least two or three years will be required to get better technologies with higher throughputs. It will take more than five years to go past one-off manufacturing.’

Printed weapons
Once manufacturing gets up to speed, the savings could be huge. That is what drew arms manufacturer MBDA Missile Systems into the additive manufacturing world. As MBDA’s David Duerden said, ‘The cost of the technology was killing us’.

The London-based company elected to go down the powdered metal route. For them, additive manufacturing offered the chance to produce limitless sizes and shapes of different materials, while using a lot less material.

To create MBDA’s missile structures, 30kg of billet (aluminium, titanium, stainless steel or composites) is machined down to 3kg. With additive manufacturing, the same 3kg part is made with 4kg of material. Duerden said, ‘When the material is good, it’s very good, but it only takes one defect in the build process for everything to fall apart. Our engineers were baffled that they could produce two parts to the same specifications and one of them wouldn’t work.’ With some of MBDA’s weaponry expected to last up to 50 years, defect tolerance remains a significant barrier.

The splinted bronchus
For all its failings, 3D printing is excellent at preventing people from putting their legs in their faces. According to Professor Scott Hollister, of the University of Michigan, USA, 3D-printed splints have been used extensively in surgery for more than 15 years.

In February 2012, a printed bioresorbable splint was even used to repair the collapsed bronchus of a three-month old boy. The team printed a model of the child’s airway and created a tracheal splint to put around his left bronchus. The procedure was so successful that the boy was discharged from hospital after two weeks.

3D printing has found a home in patient-specific medical devices. In the case of facial reconstructive surgery, biologics can be added to printed biodegradable scaffolds to pare three hours from surgery time and remove the need for doctors to take tissue from a patient’s fibula to attach it to the face.

Powder to the people
Despite these successes, it remains difficult to build a business model around bespoke solutions. That said, small-scale manufacturing will continue to drive advances. Veena Pureswaran, of IBM in North Carolina, USA, said, ‘Open-source software helps the eco-system around 3D printing. Designs are improved by the 3D printing community.’

One example of this is the now-infamous printed gun. As one delegate noted, the first prototype broke after firing half a dozen shots, but subsequent models have improved significantly. But while open-source software and private innovation will enhance existing products, the 3D printing industry is also providing fruitful ground for design thieves. Steve Tremlin To read more about 3D printing, visit our blog at materialsworld.tumblr.com from Dyson, based in Wiltshire, UK, explains, ‘As a business it’s the biggest problem and another reason to bring our prototyping in-house. We’ve found that it’s very easy for people to steal technology. We’ve tried to tie down our security, but we’re talking about rapid prototyping machines that are in networks.’

So, if you’re thinking of lighting a 3D-printed trail towards new territory, be prepared for what you might find when you get there. It takes a long time to gentrify a frontier town.

3D printing – state of the industry
IBM’s Veena Pureswaran was part of a team that assessed the state of 3D printing. Here are a few statistics from her presentation:

71% fewer components are needed in a 3D printed hearing aid

70% of industry leaders are unprepared for the commercial use of 3D printing

10% projected carbon footprint increase of a 3D-printed washing machine

23% the cost reduction of four surveyed products in 10 years’ time if produced using additive manufacturing. However, as Pureswaran says, ‘You would probably get that from traditional manufacturing anyway’.

To read the IBM report, visit ibm.co/1dtFAo6  

To read more about 3D printing, visit our blog at materialsworld.tumblr.com