Loughborough University customizes sprint spikes with selective laser sintering technology.

by Julie Graham, 3D Systems

Sprinters and jumpers at future international events could be wearing customized sprint spikes developed from rapid manufacturing at Loughborough University in the U.K.

These next-generation sprint spikes, created using selective laser sintering of DuraForm® Plastic, are custom built for each athlete to boost performance.

By personalizing soles, the bottom of shoes, to match the characteristics of individual athletes, Loughborough researchers maximized the performance of sprinters and jumpers. With the appropriate prescription of longitudinal bending stiffness in sprint spikes, athletes can double the amount of mechanical energy they generate at the ankle.

The design and development of the custom sprint spikes included four phases:

1. 3-D digital scans of shoe lasts (the form on which a
   shoe is constructed, resulting in the inside shape
   of the shoe).
   
2. Scans imported into CAD software, various designs
   created to test stiffness.
   
3. Sole units built with 3D Systems’ Selective Laser
   Sintering System and DuraForm® Plastic, a tough
   thermoplastic.
   
4. Customized sprint spikes tested with varying stiffness on
   the sprinter in the lab, then at the track.
   

By personalizing soles to match the characteristics of individual athletes, Dr. Neil Hopkinson and Loughborough researchers maximized the sprinter and jumper performance.

The research found that the dynamics of the ankle and foot are influenced by the mechanical properties of footwear, and further, that performance was individually maximized within the stiffness range, highlighting the importance of personalized footwear.

Personalized Footwear For Everyone

The long-term aim of the research is eventually arriving at a point when personalized footwear will be available for every consumer.

“Achieving success with elite athletes will prove to be the catalyst, allowing our processes to be applied to everyone,” says Dr. Neil Hopkinson, the principle investigator for the Loughborough project.

The three-year study began after the 2004 Summer Olympics in Athens where the difference in winning gold, silver or bronze for sprinters was incredibly narrow. Gold-medalist Justin Gatlin (U.S.) ran the men’s 100-meter event in 9.85 seconds – just 0.01 seconds faster than silver-medalist Francis Obikwelu (Portugal) and just 0.02 ahead of bronze-medalist Maurice Greene (U.S.). Researchers at Loughborough were looking for the difference between medals won and lost.

The study was performed as part of a five-year, $4 million project funded by the University’s Innovative Manufacturing and Construction Research Centre (IMCRC). This multi-disciplinary center undertakes leading edge research to boost competition in the U.K.’s manufacturing and construction industries and is funded by the U.K. Engineering and Physical Sciences Research Council (EPSRC).

Selective Laser Sintering

The SLS process enabled the Loughborough researchers to quickly build “one-offs.”

Selective Laser Sintering is an Additive Manufacturing process that uses a high-temperature laser to melt or fuse powdered plastic into solid cross-sections, layer by layer, until 3-D parts are built.

The SLS process enabled the Loughborough researchers to quickly build “one-offs,” encouraging freedom beyond what is afforded by other manufacturing processes. Sintered parts are known to be tough and durable and used for prototyping and end-use applications.

“We could have gone to molding, but it would have taken us a lot more time and a lot more money,” says Dr. Neil Hopkinson. “Time, cost and design freedom were improved with selective laser sintering.”

Loughborough University

The Rapid Manufacturing Research Group (RMRG) within the Wolfson School of Mechanical and Manufacturing Engineering at Loughborough University is recognized as the world’s leading research group in the field of Rapid Manufacturing. The group, founded in 1992, has been a recognized international leader through the development of Rapid Prototyping and Rapid Tooling technologies and applications.

Researchers took 3-D geometry from existing sprint shoe lasts and imported into Solidworks CAD software.

With more than 40 dedicated academic, research and support staff within the Loughborough facility, current research activities are focused in three areas: Rapid Manufacturing process and materials development, design for Rapid Manufacture and management of Rapid Manufacturing.

Loughborough University Sports Technology Institute is a $30 million initiative in partnership with the East Midlands Development Agency to boost enterprise in the sport and leisure sector and develop cutting-edge technology to support future British champions. It is home to the world’s largest university-based sports technology research group, partnering leading brands for over 20 years.

Part of the Wolfson School of Mechanical and Manufacturing Engineering, the Institute studies the engineering of a vast range of equipment, footwear and apparel in a wide range of sports under play and simulation conditions.