3D printing: towards a real production process

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In my previous post, I expounded my belief that 3D printing processes today are capable of being successfully embedded into a manufacturing enterprise. The emphasis of that post was on the fundamentally valuable but general underutilisation of tooling applications as well as a nod to the well-documented application of prototyping, whether for concept development or testing of part form and function. I believe one of the contributing factors to the underutilisation of 3D printing for tooling in manufacturing is that many people — even if they are professionally competent in design and manufacturing practices — overlook the breadth of opportunities available in manufacturing technology. Instead, they jump immediately to the proposition of additive technologies for the production of end-use parts and become broadly dismissive.

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Image via Intellectual Ventures

While there are some varied and innovative 3D printing applications for the direct production of end use parts today, this application of additive technology is still limited in this regard with a significant number of barriers that prevent it from competing directly with traditional production methods (injection moulding , CNC, etc).

A positive push towards production

Where direct production applications do exist, more often than not they fit into the “sweet spot” for 3D printing production, typically “low volume/high value” complex and customised parts. However, as additive technologies have developed and improved, applications have developed simultaneously. More recently, there are documented case studies that illustrate how early adopters of additive technologies have built new business models using the technologies for production at higher volumes.

Two markets in particular stand out here — orthodontics and hearing aids. With the former, case studies on companies such as ClearCorrect, Align Technology and Orthoclear are well documented, while for the latter, Siemens is a market leader.

Moreover, many aerospace companies have gone on record with their vision for AM as a series production methodology with factories housing swathes of AM machines producing lighter and stronger aerospace components. This has muddied the waters somewhat in that it is a long-term vision, not a reality today. However, there are some early signs of progress to discuss, most notably with non-critical parts. A recent example came from Airbus when it announced it had directly 3D printed more than 1000 in-flight parts for its A350 XWB aircraft with the certified ULTEM 9085 material from Stratasys.

While this does illustrate positive and forward momentum, there are still numerous obstacles that prevent additive technologies from competing with traditional processes for series production.

Barriers to 3D printing & AM for series production

Real time process control and monitoring

The nature of additive technologies, building parts one layer at a time, means that errors can be built into any part in any given layer. Thus part quality can vary not only from part to part, but from layer to layer — visible on the surface, or, more worryingly, internally which will affect structural integrity.

This is not a problem for non-critical parts and products where AM is a good fit — for example with indirect and direct jewellery production. However, for more traditional manufacturing disciplines and the volume production of critical parts (aerospace, medical, automotive, etc.) where quality control is necessarily stringent, it is probably this issue above all others that has affected adoption of AM processes for series production applications. Of course, all production processes work within a tolerance range, but for AM the fluctuation — and the risk — has been too great to date.

The solution is to demonstrably prove the additive process of choice in terms of consistent repeatability and by way of in-process qualification. Indeed this issue has been identified by a significant number of industrial platform vendors and a great deal of R&D has been undertaken over many years within academic research labs and by the vendors themselves. The results from this work are just now becoming visible as industrial AM platforms are facilitated with in-process control software that permits parameter control, full process monitoring and documented part analysis.

What this means is that parts produced can meet designated quality control standards off the machine and are fully traceable. But this is not something that has happened fast, and companies such as SLM Solutions, Concept Laser, EOS, and Renishaw only formally introduced these capabilities very recently. Buy-in will take even longer.

Another start-up company that points to significant development in this area is 3DSIM. It is important not to be diverted by the “start-up” moniker here. Despite 3DSIM being a relatively new business entity, it was co-founded by Professor Brent Stucker. Professor Stucker has more than 20 years of experience performing research on AM technologies, their applications, and, significantly, identifying barriers to adoption.

His research has included new materials development, computational modelling and novel applications for AM. There is only a very small pool of people in the world with that sort of longevity in the additive manufacturing industry, with hands-on experience and the depth of understanding that comes with it. Thus, 3DSIM seems well-positioned to facilitate 3D printing for critical manufacturing and production applications.

Speed

As I alluded to in my first post, the additive processes themselves are currently not that fast — specifically during the actual build. But if you then consider typical post-processing operations it gets much worse. The post-processing stage of most industrial 3D printed builds is invariably time consuming and expensive (and nearly always overlooked in any marketing materials). For metal processes this is compounded further as the removal of supports and polishing/sanding is exponentially more difficult than for plastic or polymer processes. Thus the issue of speed raises a couple barriers then, but not necessarily insurmountable ones.

On the build speeds there are four processes that promise to address this issue. I say “promise,” because none of them are actually commercially available yet. In 3D printing land, many promises have been made over the years and never quite realized. When considering new propositions such as those that follow I advise cautious optimism. Three of the four new 3D printing processes are due for release this year, namely:

  • CLIP (a polymer process from Carbon)
  • Multi Jet Fusion (MJF - a plastic powder bed process from HP)
  • Nano Particle Jetting (NPJ- a metal inkjet process from XJET)

The fourth process is a bit further out – called High Speed Sintering (HSS) it is the one that likely has the most potential to really compete with traditional series production processes but currently has a commercial release date of 2017. Developed by Professor Neil Hopkinson over more than a decade, initially out of the University of Loughborough and more recently the University of Sheffield, the HSS process will reportedly produce high volumes of parts at speeds that compete or improve on traditional manufacturing techniques while also improving part functionality and aesthetics.

In a conversation last year, Professor Hopkinson said:

It is an economically viable, high production rate system, and I expect volumes for a single platform to go up to one million parts per day. The vision for this technology is that it will be available to platform manufacturers under non-exclusive licenses, thus opening up supply chains for the equipment market in a similar way to how the injection moulding sector works.

Like I said, cautious optimism.

Beyond the build process though and back to post-processing there is a need for automation — an issue being addressed by the likes of Concept Laser and Additive Industries with their versions of Factory 2.0.

Verification

Once finished, verification becomes an issue and automated metrology capabilities within an AM platform for fast and reliable post-process verification of parts is the goal here. Unsurprisingly, Renishaw has a jump on this, but other industrial AM vendors are targeting the demise of this barrier too for their customers.

The Big Picture

While each of the barriers highlighted here are valid and have demanded specific R&D, the real key to unlocking the potential of AM for series production is consideration of the entire process chain — it actually goes way beyond just the 3D printing process itself. The design, the build, the finish and the verification demand a holistic approach and technology innovation that needs to be embedded in tandem to fulfil said potential.


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