Charles Hull and the Additive Manufacturing Revolution

By Daniel Alter, MSc, MDT, CDT

March 11, 1986 marks an historic breakthrough in a technology that is now driving today's global revolution in manufacturing. It is the date that a US patent for "Apparatus for Production of Three-Dimensional Objects by Stereolithography" was issued to the pioneering innovator Charles Hull. The patent was the culmination of more than 4 years of experimentation with the concept of stacking layers of liquid photopolymers and hardening each layer using ultraviolet light to form a 3D object, thus giving birth to the concept of 3D printing and additive manufacturing.

Today, 3D printing technology is instrumental, if not essential, for numerous major industries such as automotive, aerospace, medical, and consumer electronics to quickly print working prototypes or end products. The applications are endless as researchers continue to find new ways to utilize this technology. For dental laboratory owners and managers, additive manufacturing has become a focal point for optimizing digital workflow production. From printing models (from CAD or intraoral scans) and wax patterns for casting or pressing to the production of long-term, end-use prosthetics, many in the dental technology profession believe additive manufacturing promises to be the leading method of fabricating dental devices in the future.

At the age of 79, Hull shows no signs of slowing down as he continues to think of ways to innovate the 3D printing process and materials. IDT sat down with the "father of 3D printing" to ask him to share his journey, insights, and vision for the future of additive manufacturing.

IDT: Can you share with us your journey from concept to realization with the founding of stereolithography?

CHARLES HULL: I started working on the idea of 3D printing back in 1982 and finally in 1986 created a technology that worked.

After being employed as an industrial researcher for DuPont, I moved to a smaller company in California that used ultraviolet light to cure thin sheets of liquid plastic. This process sparked me to think: What if we could print and bond layers of UV-hardened plastic to make prototypes and parts? In the 1980s, prototype parts were traditionally manufactured by injection molding, which was a frustrating and arduous task that I had experienced firsthand. I wanted to develop a method that could be used by engineers and designers to speed up that process. So in my spare time I began working with photopolymers to see if this could be accomplished. Finally, in 1983 I had produced the very first 3D-printed prototype and patented the process in 1986.

Although I was excited and anxious to start commercializing the technology, the owner of the company I was working for did not have the capital to move forward. So I founded my own company, 3D Systems, and then needed to raise the capital to actually develop 3D printers. That led me to a financial business-oriented partner and together we developed the first stereolithography 3D printer for commercial sales in the beginning of 1988.

IDT: How did the markets react to this technology when it was first introduced back in 1988?

CH: Some market segments responded very positively. However, the major barrier back then was that 3D graphics or CAD either did not exist or were in their very early stages. Some of the more advanced companies in the aerospace and automotive industries were working with 3D CAD, and they were already spending the capital for 3D technologies. The automotive industry turned out to be our first major adopter. At that time, Detroit automakers were not in very good shape. They were searching for tools and technology to speed up their processes so they could get cars out on the market faster and also improve the quality through constant and rapid design iterations. All three of the big car manufacturers really embraced 3D printing as a solution to those challenges. Over time, 3D printing spread to other industries as 3D CAD matured and became more readily available in the 1990s.

IDT: In terms of the dental industry, what, if any, remaining hurdles or challenges is additive manufacturing still contending with?

CH: The medical and dental industries have many application and material needs for this technology. That said, even though we have had a wide range of dental applications on the market for the past 10 years or so, medical applications have been our fastest growing segment, while dental, interestingly, has not accelerated at that same pace. I think that has to do with developing printers that meet the specific needs of that market and the materials to meet the needs of those market applications. 3D printing is very much about material science. You can make a really great 3D printer, but if you can't print the right material, it doesn't serve that industry's needs. Over the past few years, 3D Systems and our partners have done a great deal of research and development on printable materials for dental laboratories and dentists to meet their specific needs, to move digital dentistry forward.

IDT: Is the micron accuracy required by the dental industry a challenge for 3D printing?

CH: No and yes. 3D printing can be very accurate. The challenge is developing a printer capable of printing the materials that the market needs, at a price point that is attractive to the dental laboratory. For some time we have marketed very accurate 3D printers, but they cost upward of $300,000 and that price point is not feasible for dental laboratories. Smaller, less costly 3D printers have been making stronger inroads into the dental laboratory industry.

IDT: What do you envision additive manufacturing accomplishing in the next 5 to 10 years in the dental space?

CH: We are aiming to provide solutions for every application dental laboratories require, whether it is producing models, patterns, or composite crowns. A long-term challenge would be to print tooth structures directly with natural color and opacity, and we will look at that possibility. I can envision that happening, although it is difficult to pinpoint a time frame when that might be accomplished. I know it is a want and a need in dentistry. As far as other innovations in the near future, I would assume driving down the costs and improving productivity will continue to evolve over time.

Regarding whether or not 3D printing will become mainstream in the dental office, I don't know the dental world well enough to predict its migration from the dental laboratory to the practice. However, my guess is some of it will. That said, if I were a dentist, I think I would want to spend more time at the chair treating patients than designing and 3D-manufacturing in the back room.

IDT: Are there research projects on the horizon involving the development of 3D-printable materials that may challenge ceramics or zirconia?

CH: I believe that in the future 3D-printable composite materials will provide the best dental solutions. Our technology is based around making better, more capable composite materials.

IDT: Some in the dental industry believe that 3D printing will overtake milling as the preferred production methodology. What are your thoughts?

CH: Certainly our goal is to do it all with 3D printing.