From personalized medicine to drones, 3-D printing – the additive fabrication of objects by depositing and patterning successive layers of material – has been touted as an enabling platform for applications ranging from the universally desirable (lighter, more efficient aircraft) to the inevitably controversial (printed firearms).

While it has become a hot topic in the press only recently, 3-D printing began in the 1980s with the invention of stereolithography, which works by patterning layers of a liquid photopolymer resin using an ultraviolet laser. This approach sparked the invention of a plethora of other 3-D printing technologies that have enabled the on-demand production of physical objects of virtually any shape directly from digital models.

Since 2006, the emergence of low-cost 3-D printers aimed at consumers and hobbyists has led to a surge of public interest. Meanwhile, the use of 3-D printing continues to spread to new sectors, and expanding capabilities are making the technology attractive to major players in industries like medicine, electronics, and oil and gas.

Industrial benefits of 3-D printing

Rapid prototyping – making single, unique parts for the testing of new designs – remains the primary industrial application for 3-D technology. Producing a traditional machined mold or other tooling for a single prototype can require tens of thousands of dollars and weeks or months of time, but 3-D printing enables production of the same part, often overnight, for only the cost of materials. This accelerated production cycle means engineers can test more ideas and pursue more design iterations to ultimately develop superior parts.

As 3-D printers decline in cost and improve in resolution and as materials selection and properties improve, these are beginning to move beyond R&D groups into low-volume manufacturing applications (tens to a few thousands of units) where the process costs for producing new parts are particularly high. For example, jet engines contain high-performance titanium, nickel, and cobalt-chrome alloy parts that are particularly difficult and expensive to machine.

Currently, the complex shapes needed can only be made by casting, machining, and then assembling multiple pieces, often throwing away as much as 90% of the high-performance alloys used in the process. In contrast, 3-D printing technologies can produce the final part structure in a single step with greater than 90% material utilization, saving on tooling, assembly, and materials costs. GE is using 3-D printing for the nozzles in its next-generation jet engines, set to fly in 2014.

These advances will shift 3-D printing from a prototyping tool to a production one. Overall, the market for 3-D printed parts will grow to US $8.4 billion in 2025, of which $4.4 billion will be for production parts rather than prototypes.

Challenges to wider adoption

Despite its appeal, 3-D printing is still too expensive to make additive manufacturing truly ubiquitous. The most advanced 3-D printers today cost more than $1 million. In addition, 3-D printing processes are slow – production can require hours per vertical inch of part, which may be sufficient for prototyping but is impractical and costly for large-scale production.

Materials required for 3-D printing also cost 10 to 100 times more than their bulk resin or powder counterparts. This is due in part to the tight purity, composition, and size uniformity requirements of printing processes. However, much of the high cost comes from the fact that most 3-D printer manufacturers require users to buy their own branded-material feedstock, sold at a high margin, similar to the ink cartridge revenue model used by inkjet printer manufacturers.

The performance of printed materials – particularly polymers – cannot match the same material made with traditional processes. For example, the z-axis strength of printer plastic tends to be lower than injection-molded polymer due to weaker interlayer bonding. In addition to this issue, sloped edges on 3-D printed products typically exhibit a staircase effect, which must be smoothed out by post-processing steps.

Finally, a printer company’s materials selection is limited to a tiny fraction of the options commonly available for traditional production methods. This makes 3-D printing a difficult proposition for many companies considering the technology for their manufacturing.

Materials, printer development

Challenges notwithstanding, enterprising users are finding valuable uses for 3-D printing outside of prototyping. Some uses are high-end: Current 3-D printers using process know-how and the best available materials – aerospace- and medical-grade alloys as well as high-performance polymers like PEEK and PEI – already outperform traditionally manufactured parts in niche applications.

As these capabilities mature, the rapid onsite manufacturing of high-quality parts in any industry becomes a greater possibility. This possibility, in turn, has sparked interest – though not yet use – in production applications such as those that may be required on an offshore rig, where downtime while waiting for replacement parts can be extremely costly, sometimes as much as $500,000 per day.

In the long run, the greatest value associated with 3-D printing may be that it enables the manufacturing of products not able to be manufactured by any other means. Even low-end 3-D printers have demonstrated that they can produce multifunctional objects in a single step with no assembly required.

As a result, developers are targeting composites, or metamaterials, that obtain unusual properties by patterning objects’ composition at the 10-micron to 100-micron scale. Just in the past year, MIT researchers showed how conventional polymers were able to increase in toughness by a factor of 20 when mimicking the microstructure of bone. At the University of Colorado, researchers printed an elastomeric material with thermally activated shape memory for folding, stretching, curling, or twisting. More recently, an as-yet-unnamed Canadian startup announced that it has invented a process for printing continuous fiber-reinforced plastics, which would allow for 3-D fiber placement patterns previously unavailable for conventional molding.

Unlimited potential for innovation, efficiency

Though it is unlikely to replace traditional processes for high-volume production, 3-D printing has the potential to reshape the supply chain and economics of manufacturing processes while expanding the range of manufactured materials and structures. Since the technology can be used to produce parts on demand, on site, and as needed, it has the potential to simplify the supply chain and enable reduction of expensive and energy-squandering inefficiencies such as transportation fuel consumption, idle equipment, and idle inventories.

Such improvements go beyond the walls of any individual entity or industry since 3-D printing enables instantaneous sharing and delivery of code, material recipes, process variables, and fabricated parts across companies and continents. As material developers, printer companies, and end users work to realize that potential, they will not only need to address technical and commercial challenges but also create new business models, design paradigms, and partnership networks to support their endeavors.