Boom time for additive manufacturing

7th March 2014

There are almost as many different additive manufacturing techniques as there are materials, so outsourcing is the watchword. Boris Sedacca reports on recent developments.

In January 2014 the UK Chancellor of the Exchequer George Osborne announced £60 million of new funding for the development of new high-tech aerospace technology at the Manufacturing Technology Centre (MTC) in Coventry. The funding will also support the creation of a national centre for additive manufacturing or 3D printing technology to develop new products for aero-engines and aircraft landing gears, as well as automotive and medical devices.

Additive manufacturing goes back a couple of decades. Pera Technology pioneered one additive manufacturing method that involved a bath full of thermosetting resin where a laser adds layer by layer in two dimensions on a surface.

"We have been involved with 3D printing for over 25years now, mainly in the areas of rapid prototyping using laser cured thermosetting. In the early days, you had large baths of thermosetting resins cured by laser with your solid structure growing out of this bath," recalls Paul Tranter, chief executive of Pera Technology. "Since that time, we have been involved with a number additive manufacturing processes, latterly with the development of a process that creates 3D circuit boards using an additive copper process which has been commercialised over in the US."

Traditionally, a substrate with a copper film bonded to the top was etched or machined to reveal a track. By using additive methods, Pera claims it can reduce copper waste by about 70 per cent by pre-treating the polymer film in those areas where the tracks need to appear.

This gives about 90 per cent of the conductivity of bulk copper, so thicker tracks are needed. Track width is a barrier so part of the reason for doing surface treatment of polymer film is to encourage liquid surface tension in a similar way that waxing a car causes a beading effect for water.

"We were effectively entering the surface of the polymer film in order to get surface tension so that the ink droplets would flow to the desired areas, so we are no longer restricted by droplet size in terms of copper track width," Tranter explains.

"We can deposit say a 0.5micron diameter copper droplet but with very small droplets the physics start falling to pieces, which means drops cannot be placed accurately or break up into smaller drops. What we were able to do was to put effectively a large drop over the area that we treated and then it would selectively flow according to its surface tension."

Pera has done a lot of 3D design and rapid prototyping in the past to test new products including steering wheels for Formula1 cars. Every day, there is a new material that can be used for additive manufacturing and there is a trend from mass production towards rapid customisation. This means the ability to rapidly reconfigure a base product according to customer specifications without making the product cost itself too prohibitive. Pera has observed this trend in the market from consumer goods to specially engineered products - customers are willing to pay a small premium for something that is bespoke or customised.

The company still has some 3D printing capability in house but this is not a core competence of the business any more, whereas 10 years ago, it was very much a key part of the business.

Working with German and Dutch partners to build the process from scratch, Pera produced initial prototypes of radio frequency identification (RFID) antennae and flexible circuit boards using this technology. Tranter believes that one of the significant barriers to future growth that needs to be overcome is product liability.

The design of a nebuliser would appear to be an unlikely breeding ground for 3D technology, but in the case of The Technology Partnership (TTP) it helped to develop a droplet printing technology which the company claims greatly simplifies both the construction of the print head and increases the range of materials.

The electronic nebuliser enables liquid medication to be inhaled through the lungs with as much as 90 per cent efficiency. In partnership with PARI GmbH, a leader in efficient aerosol delivery and pharmaceutical formulation development, TTP's proprietary electronic atomiser technology was developed to create an innovative inhalation system for treatment of respiratory diseases.

Claimed to reduce treatment time by more than 50 per cent, the device is silent, battery-powered and easily portable, with interchangeable spray heads that allow easy cleaning. More reliable and serviceable than traditional compressor-based systems, it is designed for use with all inhalation medications approved in Europe.

TTP asserts its Vista 3D is the first printer technology available with multi-material capabilities. The print head ejects droplets of various materials, the most common form of which is polymer-based but also for metals and ceramics, and even biological cell materials.

"3D printing or rapid prototyping is a great tool for exploring the properties and behaviour of materials for different products," enthuses Dr Allan Carmichael from TTP. "It is also a wonderful communication tool, so instead of presenting 3D drawings which take skill and knowledge to understand, you are able to show a physical model."

One of the first things Carmichael and his team explored was depositing metal tracks for small electronic circuits like RFID antennae, unlike conventional etching away of bulk metal material on a substrate to leave circuit tracks and antennae patterns. By thermally sintering a metal powder, the conductivity is close to that of a bulk metal on a substrate, providing the ability to print capacitors and resistors on conducting tracks.

Vista 3D can print large (50µm+) particles and more viscous and volatile fluids. Up until now, 3D printing has been restricted to single material types or families of the same material, such as UV cured acrylic basic resins, waxes, plaster (gypsum) materials and metal powders, all of which have to be used separately.

Aerospace drives growth of additive manufacturing

UK Government investment in a national centre for additive manufacturing is part of the £2 billion of joint government and industry funding for the Aerospace Technology Institute that will be invested in the sector over the next seven years. It will make sure the UK has the manufacturing capability needed to meet a growing global market which already generates £24 billion a year for the UK economy.

The government will provide £30 million in funding, which will be matched by industry.

The UK Chancellor made the announcement at a visit to the Manufacturing Technology Centre, part of the government's 'High Value Manufacturing Catapult' centres which promote high end manufacturing in the UK, providing world-class capability and equipment, such as the world's largest commercial laser.

The UK is currently number one for the aerospace industry in Europe and second only to the United States globally. The aerospace facility will allow companies to develop new materials such as lightweight carbon fibre for use in planes, jet engines and civil helicopters that will be exported around the world.

The High Value Manufacturing Catapult allows companies of all sizes to develop technology from new concepts to commercial reality using state-of-the-art machinery and expertise which is shared between members, reducing the costs to business and ensuring that the UK's excellence in design and research is translated to marketable products.

Aerospace is just one of the areas of 'high value manufacturing' that the government and industry are supporting through the HVM Catapult programme to stimulate growth in British manufacturing

Other high-value manufacturing includes the development of new efficient vehicles and electronics, pharmaceuticals and nuclear technology.

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