3D printing fast tracks custom orthotic for a child in need
Imre Patterson has a smile that lights up any room he walks into. Imre was born with a femoral discrepancy, causing one leg to be shorter than the other. He meets the daily challenge of walking with a heaping dose of tenacity, using a heavy, manufactured foam shoe to keep up with other active kids his age.
Currently, his family is allowed only one of these shoes per year. But as anyone with a young child knows, they grow out of their shoes at a rapid pace. Studies show that the feet of children between the ages of three to five years grow by about half a size every four months. His eagerness to embrace life one step at a time led his family to look at 3D printing as a possible solution for their son. A family friend connected the Pattersons with Dinsmore Inc.’s 3D Printing and Additive Manufacturing services in Orange County, Calif.
After meeting Imre, the team at Dinsmore immediately started working on finding a 3D printed solution to help him do all the things he loves to do.
3D printing technology has progressed significantly in technologies that are able to produce functional, end use production parts. When it comes to someone’s quality of life, finding the best fit combination of technology and materials is crucial. The team at Dinsmore used its 28 years of additive manufacturing expertise to carefully consider multiple factors and weighed them against the material properties of each 3D printing technology. Imre needed the platform of the shoe to be a significant height off the ground, which called for a material both durable and lightweight.
Building with Multi Jet Fusion Technology
When designing the first version of Imre’s shoe, Dinsmore decided that the best combination of technology and material would be HP’s Multi Jet Fusion and Nylon PA12 material. Multi Jet Fusion or MJF builds layer by layer upon fine grains of powdered material. Starting with a thin layer of this material, the process uses an array of inkjets that apply fusing and detailing agents to selectively melt fine grains of powder. While one bar passes over the material with the agents, another passes perpendicular to it providing fusing energy, causing the saturated material to harden and form, building upon the layer beneath it. Once the part is 3D printed, the surface that holds the completed part or the build platform is removed and carted into the processing station for cooling, then removal of the excess from the part.
Multi Jet Fusion produces parts with intricate geometries, and because of the unique binding and fusing process which the material undergoes, the parts are isotropically strong or equally strong in all directions.
Understanding the capabilities of the technology and material are deciding factors when designing a load-bearing part, especially one which will be worn by an active child. The team at Dinsmore 3D printed a lattice using Multi Jet Fusion technology and Nylon PA12 material to create a strong, durable, and lighter platform for Imre’s shoe compared to his original foam orthotic.
Although this shoe was more durable and lighter than his manufactured foam boot, another round of shoes was needed to keep up with Imre as he grew.
Stepping into the Future
Dinsmore partnered with multiple talent to innovate deeper on the second version of shoes for Imre. A few more steps would be needed for this new version. To further improve, Dinsmore collaborated with Chris Hillyer and his team at Deckers Brands, experts in the footwear industry who provided the components of the TEVA and UGG shoes to bind with the 3D printed midsole, essentially sandwiching it between the upper and outsole.
In order to fit all these components together, the upper components of the shoes were 3D scanned by Conner Morris at the SEMA Garage. A FARO arm with a blue laser was used to 3D scan the shoes, because of its ability to quickly capture high definition data in the form of a scan cloud. This scan data was then processed into a CAD file which the Dinsmore team used to design the CAD models specifically for additive manufacturing. The team shaped each 3D printed midsole to fit the corresponding TEVA and UGG shoes that they were bonded to. The original lattice design from the first shoe was revised into a version suited for printing in Carbon’s Digital Light Synthesis (DLS) technology.
DLS technology uses light to shape the liquid material into the lattice that Dinsmore redesigned for the midsole to conform to each shoe it would be bonded to. The Dinsmore team chose to use DLS technology because of its ability to 3D print the midsole using an elastomeric polyurethane based material. This material is currently in production for a major brand of athletic shoes and would provide Imre with a durable, lightweight, and responsive midsole. Production Development Engineer at Carbon, Jason Lopes, who assisted with designing the lattice structure specifically for the technology, commented that “as he grows bigger, we can put a scale model on it.”
DLS works by projecting light upwards into a reservoir of UV-curable resin through an oxygen-permeable window. As a sequence of UV images are projected, the part solidifies from top to bottom and the build platform rises. The continuous liquid interface production (CLIP) used during this process prevents layers from being formed within the part. Instead, oxygen prohibits light from curing the resin closest to the window (known as the “dead zone”), which allows the continuous flow of liquid resin beneath the printed part. Just above the dead zone, the UV light cures the part as it rises.
Because the Digital Light Synthesis process does not print layer upon layer like traditional additive manufacturing, the surface of the parts is smooth and isotropic, behaving consistently in all directions. This high-quality finish, combined with the chemical reaction from the heated oven, results in high-resolution parts with engineering-grade mechanical properties.
Growth for the Future
Since the midsoles were designed digitally, as Imre grows, we can take the baseline of what we’ve already done, modify that lattice structure, and create another midsole. One of the benefits of 3D printing is its ability to design upon previous data and adapt it to whatever necessary changes need to be made in the application. Both Imre and his family are actively involved with Dinsmore’s 3D printing experts to create solutions for Imre as he strides into a future as bright as his smile.