Has all this talk about Cinderella got you looking for a shoe that fits? If you are a runner, you know how many factors you have to consider when shopping for shoes: weight, structure, cushioning, and specific training goals are all important considerations when choosing a shoe. Every runner has a unique and measurable stride. Until now, runners have had to settle for “close enough” standardized shoes produced by conventional manufacturing methods. Now, Boston-based New Balance is paving the way for a 100% personalized running shoe experience.
Every runner has what’s called a “foot strike pattern”, which includes several variables, such as a degree of pronation (the degree to which a foot rolls inward with each stride), braking, and propulsion forces. All running shoe manufacturers are continuously exploring new methods of design and production in order to compete in the fast moving running shoe industry. But, recently, New Balance started experimenting with 3D printing in order to print custom spike plates with plastic sintering technology from EOS to suit the foot strike patterns of their elite athletes.
The spike plate is found on the underside of the shoe and is what provides traction when the runner is speeding down the track at the speed of light. New Balance uses a proprietary process to collect the personal data they need from their elite runners, and they send it to their sports research laboratory for them to translate the athlete’s information into an advanced algorithm, which creates the optimal spike plate design for that runner. This design is then additively manufactured from plastic powder by an EOSINT P 395 SLS system.
“There are so many great things that came out of this process, compared with the methods we used in the past to develop and manufacture products. We record a runner’s data, generate multiple plates we feel will meet his or her needs and provide several pairs of track spikes simultaneously for them to try,” said Sean Murphy, senior manager of innovation and engineering at New Balance.
The next step? Runners from Team New Balance test them out. Each athlete identifies and responds to every subtle variation. These tests help determine the relationship between the force plate and the foot generating a three-dimensional vector recreation of the foot strike. The sensors within each test shoe track where the most and least pressure is being applied with each strike and, in general, how that runner’s foot is interacting with the shoe. Researchers look for areas of high pressure and make sure to pay close attention to that area of the shoe when constructing the ideal strike plate for each runner.
Murphy continued, “We establish a relationship between these high pressures and the corresponding forces to help us create a map of forces relevant to each area of the foot. A simple example is in the toe area. Generally, when you see high pressure there, it corresponds to a force that is pushing toward the heel to create a propulsive force forward. We use parametric modeling software to process this data and distribute the position of the spike plate traction elements, calculate the orientation and adjust the size of the elements, and incorporate specific runner preferences into the design.”
The personal preferences of the elite runners are also taken into consideration. After all of this information is collected, the designer cleans up the CAD and creates the final product. This involves making the necessary adjustments to the spike plate and finishing the model surfaces. After the final geometry is verified, the .stl files are uploaded to the EOSINT P 395 system where the spike plate is produced.
What are the major variables researchers have found in the spike plates of different elite athletes? Well, it often depends upon the distance and the kind of race the athlete is competing in, but general variations include fit, stiffness and the design of the plate. All of these factors influence the performance and comfort of the runner.
Customization of spike plates for athletes with different strides and competitive goals is nothing new. Until the advent of 3D printing technology, running shoe companies created injection molds of various sizes and styles every year. This process cost them thousands of dollars annually. Now, the laser-sintered batch produces fewer plate pairs and takes 5-6 hours to manufacture.
“By laser sintering our customized spike plates we can manufacture on demand, fluidly adjust our process to accommodate different sizes and widths, and update designs without the continuing capital investment required by injection molding. Incorporating the laser-sintered spike plate also allows us to achieve a five per cent weight reduction compared to traditionally manufactured versions. For a competitive runner, the smallest change in weight can make a significant difference.” Katherine Petrecca, business manager of New Balance, said.
So, not only is this a cost efficient solution for running shoe manufacturers, but it is a sweet deal for runners, whose business is speed. This is a good deal for everyone. New Balance’s 3D printed spike plates are made with a proprietary blend of nylon powder, which results in optimal tensile and flex moduli while minimizing build time. This high performance material was developed in conjunction with Texas-based Advanced Laser Materials in a bid to kick to the curb the typical thermoplastic polyurethane and polyether block amide track spikes.
After these highly customized spike plates are finished being manufactured, even more care goes into them as plates are processed through a technique called bead blasting and processed through a proprietary system of aesthetic coloration and finishing.
So what does Team New Balance think about their new track spikes? How does this highly customized shoe affect their performance? Kim Conley, a US Olympic runner and a proud member of Team New Balance thinks they may be the perfect fit for elite runners everywhere. She has worn her bespoke spikes for several competitions including World Championships. Conley’s personal best in both the 3000 meters (8:44.11) and 5,000 meters (15:08.61) has been attained with 3D printed laser-sintered New Balance spike plates.
“My shoes are critical to my performance. They are the most important piece of equipment I have. As a professional runner, you obviously want the most effective and comfortable spike plates for competition. For me, they are the ones New Balance designed, based on the curve running data their development team collected. They provide better traction and less pressure on the outside of my foot, which allows me to focus on my race plan and not worry about my equipment,” Conley said.
But when do we get our own custom running shoes? When does the 3D printing technology allow for running shoe manufacturers to move beyond spike plates for elites and start producing highly customized running shoes for non-Olympians? Currently, New Balance is only offering this technology to their elite athletes, but Katherine Petrecca says 3D printed shoe technology will eventually be open to everyone:
“Design-driven additive manufacturing really holds the promise of more on-demand production and more individually customized designs. The spike plates are the first step we have taken with our athletes. As the material options expand, as our own proficiency with the technology increases and as capacity for additive manufacturing grows, we believe we will be able to bring 3D printed products, in some format, to the everyday consumer.”
