Titanium 3D Printing With Class

Duke University’s new production-grade titanium 3D printer is giving students and faculty rare access to the fastest-growing segment of the additive manufacturing industry. Two groups of Duke engineering undergrads have been using the state-of-the-art printer as part of a senior design project focused on producing titanium devices for orthopedic surgery.

Although not destined for testing or use in real patients, the student-made devices are made to the same standards as the successful, FDA-approved titanium devices now reaching the market. As early adopters of a technology not yet widely available in the academic world, Duke students are gaining a competitive edge in the job market.

Titanium’s physical properties are uniquely applicable to orthopedic devices, and 3D printing overcomes the challenges of shaping the notoriously tricky metal into highly complex shapes. Both student groups are taking advantage of those capabilities in their projects. One team is developing titanium spinal fusion cages used to prevent painful contact between vertebrae damaged by disc or cartilage degeneration. The other team is creating customized titanium scaffolds to support large bone defects. With both types of devices, doctors seek materials and geometries that not only keep bones in position but also that encourage them to regrow in and around the implant. Plastic devices lack strength and don’t promote maximum bone growth.

Many other metals, on the other hand, are too hard and aren’t compatible with the diagnostic imaging techniques doctors use to monitor healing. “The titanium printer is a really great opportunity because it lets you create structures that you couldn’t make using normal manufacturing techniques,” said Samantha Sheppard, a senior in mechanical engineering. “We’re able to create porous structures that are better for bone in-growth and that could really only be made with this printer.”

3D printed titanium spinal spacers. Image: Duke University.

Ken Gall, professor and chair of mechanical engineering and material science, who headed the project to acquire the printer, said “For the students to actually be able to make real parts that match what the doctors want designed and then to actually test those parts is something that you would rarely see at a university.”

The students are working on a 3D Systems ProX DMP320 direct metal printing machine set up to print medical-grade titanium parts in a build area of approximately 10 x 10 x 10-in. In direct-metal printing, titanium alloy power particles are deposited into a desired shape and melted into thin horizontal layers using a high-precision laser. The technique is superior to traditional subtractive or casting technologies for the production of small, complex titanium parts with challenging geometries. At Duke, the metal printer is used to produce high-quality finished parts based on prototypes built on one of the 60-odd polymer 3D printers in the university’s Innovation Co-Lab. Gall said the technology’s impact will cut aross the university. "It is something for the entire Duke community, for all students and faculty in all fields of study, to utilize in designing their next breakthrough." The university plans to hold special print weeks, during which users can pay to have their designs printed for only the cost of the titanium power, currently about $100 per pound. Because the printer recycles unused titanium powders after each job, actual user costs would be based only on the weight of their finished objects.

Metal Market Materializes

The Duke project is just one example of the innovative strategies universities are using to prepare engineering students for the additive manufacturing era. As 3D printing gains wider acceptance in engineering practice, more and more jobs are calling for some level of prior experience with the technology. Indeed, a 2015 study published by the IEEE found that 35% of engineering jobs listed during a one-month period required 3D printing skills. Teaching the basic principles is a straightforward matter, but connecting students with the latest equipment and software is more complicated in the university setting. Many engineering schools have readily invested in traditional, low-cost polymer 3D printers but the cost and complexity of high-end printers for specialty metal and other materials have limited students’ access.

The opportunity to design and print high-end titanium objects is well-timed. Titanium printing appears to be moving beyond its original low-volume, high-value market niches and toward mass-production applications. According to market research firm MarketsandMarkets, sales of metal 3D printing technology are growing at a five-year compound annual rate of 31% through 2020, when it is expected to hit $776.8 million. Titanium is the fastest growing metal material in the market, and aerospace and biomedicine remain its primary big-ticket applications.

Michael MacRae is an independent technical writer based in Eugene, OR.