Advances Add Up For 3D Printing

HANK HOGAN, CONTRIBUTING EDITOR, hank.hogan@photonics.com

For additive manufacturing, aka 3D printing, 2016 could be a very good year. Some big names are entering the field, advances promise better processing and signs point to movement into the mainstream. At the same time, the industry is working on developing standards while continuing to lower cost and improve performance — thereby addressing issues that have hindered adoption of additive manufacturing.

Nine parts additively manufactured on a single sub plate, ready for final subtractive manufacturing via traditional milling, grinding and so on. Photo courtesy of Georg Fisher Machine Systems.

One result looks to be explosive growth. Titanium powder is a raw 3D printing material, and its consumption is a proxy for overall additive manufacturing activity. That appears strong, based on projections for the titanium powder market over the next decade.

“That is about a 31.4 percent compound annual growth rate,” said Scott Dunham, senior analyst at SmarTech Markets, a 3D printing analysis firm.

SmarTech Markets forecasts the titanium powder market will grow from $66 million worldwide in 2015 to $776 million by 2024. Titanium is favored in aerospace and medical applications, two areas willing to pay a premium to produce high-performing critical parts. This may be for orthopedic implants, aircraft support structures and engine components. GE, for instance, is making all-important fuel nozzles for its latest engines via additive manufacturing.

A variety of shapes can be produced by additive manufacturing, and researchers are investigating how to improve this 3D printing process. Photo courtesy of Siemens.

What also sets medical and aerospace apart is that both are no longer interested in prototyping alone. “In medical, they’re printing a lot of parts for actual final use in patients. In aerospace, there’s an impressive number of parts that are scheduled for actual production in the coming months,” Dunham said.

An indication of this increasing maturity can be found in what Siemens AG is doing. A diversified technology and manufacturing company, Munich-based Siemens makes, among other things, gas turbines. The company today uses additive manufacturing to create better and higher-performing burner tips for those turbines.

Eventually, a company goal is to have turbine blades produced through 3D printing. That would enable the creation of cooling channels inside the blades, boosting their efficiency. However, it’s not possible to do so with currently available additive manufacturing due to the stress the blades experience as they spin inside a turbine. Siemens is, therefore, actively engaged in 3D printing-related research and development.

A laser control scheme enables tailoring of the microstructure of materials of additive manufactured parts, such as these blades from Taiwan’s Industrial Technology Research Institute. Photo courtesy of ITRI.

However, the company is not involved in the production of 3D printers, according to spokesperson Peter Jefimiec. Instead it is striving to be a supplier and technology provider to builders of additive manufacturing machines, thereby helping move the technology into wider use.

“Our aim is to anchor additive manufacturing firmly in the industrial production process, which means industrializing 3D printing,” Jefimiec said.

For another data point about the move from niche status to full manufacturing, consider the entry of HP Inc. into the 3D printing market. The Palo Alto, Calif.-based company claims its Multi Jet Fusion technology, which is not photonics-based, offers up to a tenfold increase in speed and better quality than the competition.

A child’s tracheal splint created by additive manufacturing is shown above. Laser-sintered parts are customized to the individual. Photo courtesy of Leisa Thompson, Photograpy/UMHS.

Those statements may be widely and independently confirmed once the printers hit the market some time this year. Even before that, though, the fact that a company with a long history as a dominant player in the printer market will now be selling additive manufacturing products is significant in terms of validating the whole field.

Count Andrew Snow among those who believe this to be the case. Snow is senior vice president of Novi, Mich.-based EOS of North America, a subsidiary of Germany’s EOS. The company makes laser-based additive manufacturing systems and saw a more than 50 percent jump in revenue from 2014 to 2015, growth that Snow attributed to the widening adoption of industrial 3D printing in aerospace, medicine and elsewhere. HP’s entry could well help continue that usage climb.

Another reason could be ongoing additive manufacturing improvements. EOS, for example, is deploying real-time monitoring, using photodiodes to look at the melt pool. This will be done along the axis of the laser and also from an off-axis vantage. Such monitoring can provide a wealth of information.

“Not only does it examine the mechanical quality of the components being produced but also you’re continually monitoring the overall robustness and reliability of the hardware as well,” Snow said.

At the moment, the technology is only being used to collect information on the various material and processing parameters. Such in-situ monitoring could someday be used for part certification or in a process control loop.

Another reason for future growth may be continued development of industry standards governing 3D printing technology, design and materials. EOS, for instance, is active in the relevant committees in ASTM International, the global standards-setting body. Among other things, standards can help in designing for manufacturability. Today, this information is making its way into academic settings and the training of the next generation of engineers and designers, according to Snow.

In speaking of the future, he noted that no single material is suitable for all applications. Consequently, it will likely be true that both additive and subtractive manufacturing will be used in industrial processes in the future. As a result, there needs to be ways to integrate a variety of techniques, enabling the passing off of parts from additive to subtractive machines or vice versa with little to no human intervention. EOS is working on developing such methods, Snow said.

Nanoscribe GmbH, located in Eggenstein-Leopoldshafen near Karlsruhe, Germany, takes a different approach than other companies in its additive manufacturing systems, with the result being that it can create objects with a feature size as small as 100 nanometers, said CEO Martin Hermatschweiler. This is possible because the technique uses a two-photon process to harden a photoresist. As the name implies, this only happens when two photons are simultaneously absorbed within a small volume of photosensitive polymer.

A two-photon polymerization technique enables 3D printing of a miniature replica of the Roman Colosseum (left) as well as lens holders (right). Photo courtesy of Nanoscribe.

“It’s like having a very precise pen in your hand, and with this pen you can define where you want to polymerize the resist and do it nowhere else,” Hermatschweiler said.

The resulting structures are smooth enough to be used as an optical surface without any polishing or other post-processing. The technique is largely limited to polymers or hydrogels, although these can be functionalized by, for example, adding nanoparticles that react to the presence of chemicals or biological compounds.

Once made, the parts might be used as a mold or stamp to create others, which cuts costs. Another way to reduce manufacturing expenses would be to polymerize the skin of the resist and then use flood illumination to finish the interior.

These are examples of the ongoing trend of falling costs in additive manufacturing, one reason for its greater acceptance. Another is that systems are increasingly easy to use. This can be seen in Nanoscribe’s products by the fact that you don’t need to be an expert to run them, according to Hermatschweiler.

He thinks that the entry of large well-known industrial companies will further boost the additive manufacturing field. One way could be the development of new standards, such as is being done by the Wakefield, Mass.-based 3MF Consortium. Founded in 2015, the organization counts HP, Microsoft, Siemens and others among its members. Its goal is to define a 3D printing format to allow designs to be easily sent to applications, platforms, services and printers.

A final instance of a technological advance comes from the Hsinchu, Taiwan-based Industrial Technology Research Institute. Researchers there have developed the ability to use lasers to control the microstructure of the material in additive manufacturing. This is done through a complex beam shape with many irradiation modes that controls thermal variations in the 3D printing process, according to Ji-Bin Horng, senior principal engineer.

This control can create unique and useful properties in materials because it allows the adjusting of parameters on a minute scale, Horng said. “A turbo blade with directional microstructure will have durability 100 times higher than normal equiaxial grains. Material microstructure of key components has an optimal choice for an application.”

The approach, which is based upon what is called an optical engine, has been demonstrated in metal structures but it can be applied to ceramic, polymer and composite materials, Horng said. An advanced additive manufacturing technology, it is only in the early stages of commercialization. There has been a demonstration of the concept but no actual products produced. The optical engine could potentially be installed as an add-on to existing 3D printers, provided that they are laser-based.

One benefit of the approach is that it could help protect intellectual property. Instead of everything about a part that makes it useful being embedded only within its size and shape, some of that might be found within the material itself. For instance, the hundredfold increase in durability arising from aligning metallic grain structure would come from the manufacturing process, not the part geometry.

The extra degree of freedom derived from being able to adjust material properties could be the next advance in additive manufacturing. It would be part of a change in how designers think about parts and products.

As Horng said, “Engineers should consider the mechanical properties everywhere in the part, simulate the best design and set the related parameters.”