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Additive manufacturing: beyond prototyping

By: Chris Williams
20 August, 2014

The buzz around additive manufacturing – joining materials layer-by-layer from a three-dimensional model – is growing, particularly if the stock prices of 3D printing companies is anything to go by, but is the technology ready to go mainstream and deliver the next 'industrial revolution'?

Additive manufacturing (AM) first emerged in the late 1980s with the introduction of stereolithography, a process that solidifies thin layers of UV light-sensitive liquid polymer using a laser. Since then the technology has advanced at a sure and steady rate.

The 1990s delivered a host of advances and spawned as many new initialisms to the manufacturing lexicon - fused deposition modelling (FDM), solid ground curing (SGC), laminated object manufacturing (LOM), selective laser sintering (SLS) and direct shell production casting (DSPD) amongst them.

By the mid-1990s 3D printing was in development but it wasn't until the new millennium that processes such as direct metal deposition (DMD) brought additive manufacturing into the realm of metalworking, and researchers started to see possibilities beyond rapid prototyping.

In the last 10 years the technology has developed yet further, but despite the promise there is still substantial conjecture as to what extent additive manufacturing using metal can become a mainstream metal manufacturing process.

AM rising

Wohlers Associates is an independent consulting firm that provides technical and strategic advice on the new developments and trends in additive manufacturing, 3D printing, and rapid product development.

Earlier this year the company released its annual global study on AM and 3D printing – terms that are used interchangeably – and concluded that the market was worth some US $3.07 billion in 2013, with metal additive manufacturing growing nearly 76 per cent in the past 12 months.

Tim Caffrey, a senior consultant at Wohlers Associates and one of two principal authors of the report, said AM systems for metal parts were increasing in popularity and creating unprecedented interest and excitement.

"The industry is experiencing change that we have not seen in 20 plus years of tracking it," Caffrey said.

"What's most exciting is that we have barely scratched the surface of what's possible."

Caffrey said he expected the production of parts for final products to far surpass prototyping applications for 3D-printed parts, because the ratio of prototypes to production parts is often 1:1000 or greater.

"The money is in manufacturing, not prototyping," he said.

"The opportunity for more commercial production activity from additive manufacturing is immense."

Widespread adoption is however, still some way off. Global sales of metal-based AM machines totalled 348 last year, which while compared to 198 in 2012 is impressive growth, is still a modest number.

Equally while that growth is predicted to continue, Wohlers Associates claims it will be fuelled by sales of 'personal' 3D printers under US $5000, as much as the expanded use of the technology for the production of metal parts.

Aerospace takes lead

There are some notable exceptions. Household name corporates including Airbus and General Electric are currently using metal-based AM machines to produce complex metal parts for next generation aerospace and medical products.

Back in June GE Aviation announced that it would be opening a new assembly plant in the United States to build the world's first passenger jet engine with 3D-printed fuel nozzles. Though the engine called LEAP will not enter service until 2016 it has already become the company's bestselling engine, with more than 6,000 confirmed orders from 20 countries.

Inside each LEAP engine are 19 3D-printed fuel nozzles that are five times more durable than the previous model. Three dimensional printing allowed engineers to use a simpler design that reduced the number of required brazes and welds from 25 to just 5.

Joshua Mook, Lead Engineer at GE Aviation responsible for the 3D printed fuel nozzle said the challenge he was set by senior management was a daunting one.

"They said you have to design a fuel nozzle that has 15 per cent better fuel burn than what it's replacing, oh and by the way your customers are expecting a fuel nozzle that lasts forever in the field basically, which is a tall order," Mook said.

"The secret to designing a good fuel nozzle is proper management of air and fuel. Often I need very complex shapes, I need shapes that a machine tool cannot generate I need hidden channels or cavities that I cannot machine.

"I was personally very sceptical (about additive), but the first milestone for me was when we first ran a nozzle that included some pieces that were made with additive manufacturing in an actual combustion environment, and they survived.

"After that initial test we said additive has a chance here so we said let's design the best fuel nozzle we possibly can."

Manufacturing's saviour?

Whether additive manufacturing has been overhyped by a favourable press and high profile successes of the likes of GE's is open to debate, but Richard Hague, Professor of Innovative Manufacturing in the Department of Mechanical, Materials and Manufacturing Engineering at the University of Nottingham, is cautiously optimistic.

"Most of the 3D printing you see in the press today is based on extrusion-based technologies, but that isn't the reality of additive manufacturing. The reality is powder-based technologies where you lay down a layer of powder and fuse them together with a laser," Professor Hague said.

"Those are the techniques that give you the most design freedom, they give you the best mechanical properties, and are the most industrially relevant today – but they can only produce parts in single materials.

"We think the jetting-based technologies will be the future technology because they give the most potential for printed-in functionality for polymeric parts, metallic loaded inks, but also direct metal printing.

"No you can't make everything. The main problem with additive is the material because you are effectively producing the material at the point of cure, or fuse, or deposition, so you're not just creating the topology, you're actually creating the material at the point of manufacture as well as the topology and it's that combination that is very important.

"It's one of the technologies that is going to be exciting for a younger generation of people getting involved in manufacturing and I genuinely believe these technologies will bring back manufacturing."

Others are more reserved. Paul Philips, Managing Director of Australian machine tool and technology company Benson Machines, told IndustrySearch his company had been selling additive equipment since 2009, but had already transitioned past it.

"There are hundreds of people making 3D printers now but those 3D printers are for the most part not for production, or if they are it's for very low volume production," Philips said.

"The reality is that the cost of making parts by additive is way, way higher than by conventional methods so additive only has a niche for one-off prototyping or where conventional processes can't produce the result.

"Additive is useful I think in dental and high tech aerospace which we just don't do in Australia. Where cost is no object and where a three day cycle time to make a part is acceptable.

"Additive has been way overhyped. As technology improves they will find more and more applications but we can't hitch our wagon to additive and say it will solve all our problems, it's far from that."

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