Additive manufacturing is not a one-size-fits-all solution

Additive manufacturing (AM) – the process of building a product by putting down successive layers of raw material such as a metal powder or a plastic polymer – has been around more than 30 years.

What’s new is AM is transitioning from prototyping and modeling to a production and manufacturing technology, displacing conventional processes in an increasing number of applications in aerospace and defense (A&D) as well as other industries.

Pratt & Whitney is in the vanguard of exploring the limits of AM and helping write the standards that will guide other companies in how to use AM while ensuring products meet the stringent requirements for aircraft and spacecraft. The company is using AM to accelerate its development of more fuel-efficient engines, including incorporating 3D-printed parts into production engines.

“This was a very large milestone,” says Lynn Gambill, chief engineer, Manufacturing Engineering and Global Services.

Also in the vanguard is GE Aviation, which 3D prints fuel nozzles for some jet engines and expects to churn out more than 45,000 of the same design annually. The technology is allowing GE to fabricate the component in one piece instead of assembling it from 20 separate cast parts, cutting manufacturing costs by about 75%.

Boeing has more than 200 AM part numbers on 10 production aircraft – both commercial and military. Airbus is eyeing a point in time when entire fuselages can be printed. There is even an experimental AM unit on the International Space Station, working toward the day when spaceflight crews will build the hardware they require and recycle it as feedstock for future hardware needs.

Observes NASA Administrator Charlie Bolden, “AM is a disruptive technology that will revolutionize how we manufacture products in aerospace.”

Some technologists draw a parallel between the point where AM has evolved and where the Internet was in the mid-1990s. Back then, very few people, if anyone, could imagine the profound impact a globally connected computer network would have on commerce and life within the ensuing

10 years. Fast forward to today and the status of AM; it appears to have reached a tipping point, leading many industry observers to believe that its evolution could be just as dramatic.
 

Accelerated innovation

One of the drivers almost certainly will be the rate of innovation among inventors. Ten years ago, only 80 patents covering AM materials, software, and equipment were granted worldwide, not counting duplicates filed in multiple countries. As of 2013, that number had grown to about 600 non-duplicative patents, led by two small companies: Stratasys and 3D Systems. Last year marked what could be the start of new phase of innovation as some patents on laser sintering expired. Laser sintering – a technology capable of printing objects in plastic, metal, and ceramics to high levels of detail – is often used to make finished products rather than prototypes.

Expired 3D printing patents will allow new start-ups to leverage the technology, says Jeff Smith, director of Dassault Systèmes’ Ideas Lab for aerospace and defense. “We will see a lot of activity around the introduction of new, more efficient processes as well as new technologies, which is where the most exciting, game-changing innovations will happen.”
 

Complementary technology

What AM won’t do – at least for a long time – is displace all traditional production techniques. Not every component will be a candidate for AM and reap its benefits of cost reductions, performance improvements, or both. Therefore, companies must be certain they understand the characteristics that help determine which components are the best candidates. Typically, such parts would include a high labor-cost element, such as secondary machining processes; complex tool requirements or relatively low volumes and therefore high tooling costs; high obsolescence or scrap rates; and parts that cannot be made using conventional machining due to their complex design.

“AM is a disruptive technology, but it is not necessarily a replacement for all traditional methods of manufacturing,” says Gambill. “AM should be considered a complementary technology that needs to buy its way into the overall design and manufacturing process. Both castings and forgings will always have a role for certain A&D applications.”

Even parts made from 3D printing still require some finishing and possibly some machining, depending on how they will interface with other components.

“Additive manufacturing, while a disruptive technology, is not a one-size-fits-all solution and won’t eclipse everything else out there,” Gambill says.

If something can be produced conventionally at a reasonable cost, and the volume is relatively high, it is often best to go that route, according to Terry Wohlers, principal consultant and president of Wohlers Associates Inc.

Still, this does not diminish the unique advantages of AM – starting with the fact that 3D printing allows designers to imagine shapes that would be impossible to create through older techniques.

“As AM technologies evolve, it will open the door to capabilities we haven’t even dreamed of today,” Smith says. He foresees robotic and software technologies – each rapidly evolving – playing a major role in scalable and hybrid AM possibilities that can be used to build almost anything.
 

Certain advantages

Other benefits of AM include the ability to build parts on demand with designs such as internal cavities and lattice structures that help reduce weight without compromising mechanical performance. Complex mechanical parts – an encased set of gears, for example – could be made without assembly.

The AM process creates less scrap than traditional machining tools – a critical attribute when using expensive aerospace materials such as titanium. Some researchers believe AM can reduce the current buy-to-fly ratio from about 8-to-1 to something closer to 1-to-1.

Finally, AM’s impact on economies of scale and scope make it a natural for A&D, which in contrast to other mass production industries is largely geared toward customized production.

For all its advantages, AM is still in its infancy. The question becomes what does the aerospace industry have to do to take advantage of its full potential?

“AM will advance exponentially when we can easily establish a part’s flight-worthiness,” Smith says. “The challenge is very similar to what composites went through to gain wide acceptance for civil aviation and space applications.”

From Gambill’s perspective, the key will be demonstrating repeatability in all aspects of the AM build process. Dassault Systèmes, in partnership with the National Institute for Aviation Research, is developing solutions to these problems at an innovation center, currently under construction, that the two organizations will operate on the campus of Wichita State University in Kansas, starting in late 2016.
 

Increasing adoption rates

Another constraint that must be addressed is getting more suppliers to integrate the technology into their operations, according to some industry practitioners.

“If we get enough suppliers to start using AM, the industry as a whole will be able to take greater advantage of AM from a product lifecycle standpoint,” Smith adds.

As of last year, Deloitte Consulting reported that only a small number of first- and second-tier suppliers were proactively ramping up their existing manufacturing capabilities to be able to leverage AM for mainstream applications. That should come as no surprise, given the companies’ conservative approach to taking risks.

Gambill emphasizes Pratt & Whitney has been encouraging suppliers to adopt AM, noting, “We are seeing them eagerly embracing it.”

Whatever the number of AM users now, this much is certain: Managers will need to determine whether they can afford to wait for this fast-evolving technology to mature before investing, or whether the risk of waiting is too great. Their answers will differ, but the time for strategic thinking is now. Smart business leaders aren’t waiting for all of the unknowns to be resolved; their risk/reward calculus effectively is telling them that AM will change the way products are designed, produced, purchased, and delivered, so they are incorporating AM into their operations.

As more companies follow suit, they could face the prospect of needing to overhaul their current business models. The models they are following may not be aligned with their customers’ expectations or the business opportunities that AM almost certainly will spawn, including the ability to use AM as a competitive differentiator.

For example, suppliers should be asking how their offerings could be improved, whether by themselves or by competitors. Fabricating a part layer by layer, according to a digital blueprint downloaded to a computer-controlled printer, allows for limitless customization and lighter, more intricate designs.

Additional savings in inventory, shipping, and facility costs makes the case for AM even stronger.

“Imagine being able to digitally define a product,” says former Boeing Commercial Airplanes chief, and later Ford Motor Co. president and CEO Alan Mulally. “So that instead of having warehouses full of inventory or parts that you might need, you just make the part when you need it. 3D printing is really going to make a big difference going forward in terms of productivity and the entire inventory that you are financing.”

Many companies contemplating the use of the technology do a piecemeal financial analysis of targeted opportunities to swap-in AM equipment and designs where they can reduce costs or add value, industry observers note. However, bigger gains will come when they broaden their analyses to consider the total life cycle costs, including overhead.

Traditional boundaries will blur, meaning managers will need a strong sense of the company’s role in their core markets to decide which assets they invest in or divest. As AM technology and materials science evolves, its applications almost certainly will expand, too.

Pratt & Whitney
www.pw.utc.com

GE Aviation
www.geaviation.com

Dassault Systèmes
www.3ds.com

Wohlers Associates Inc.
www.wohlersassociates.com

About the author: Tony Velocci is former editor in chief of Aviation Week & Space Technology. He is currently a freelance author and consultant.

Read more about Terry Wohler’s research at http://goo.gl/06uL3C.