3D Printing in footwear, Part 1 Nike.

In this series I am going to look at 3D Printing and how footwear brands have incorporated it into both design and functional product with a brief explanation of the technology.

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Nike - First up we have the big boys, the swoosh first brought functional 3D printed footwear to the table in 2013 with the Vapor Laser Talon. The striking volt and black American football cleat weighing only 158.7g. Designed for optimum speed on the NFL field. Specifically for athletes to maintain their 'Drive Distance' over time.

The technical part, the part of the shoe that is 3D Printed is the outsole. It is printed using SLS (selective laser sintering) This process involves using a high powered laser to sinter (melt) a powder and build up in layers. This powder is generally a white Nylon powder which produces functioning durable real world parts as a result this process is typically a more expensive process.

The SLS build process allows intricate structures to be built without needing any support structure, the un-sintered powder suspends the part within the built. Unlike typical manufacturing processes there are no weak points in the build allowing optimisation and weight saving, during the printing process the temperature is around 180 Degrees Celsius.

Typically most SLS prints are white and they need to be disperse dyed to hold any sort of colour, you are able to see the build lines in the images here. The print resolution (The thickness of each layer) is typically 0.1mm thick layers at a time.

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It wasn't until 2016 that we saw the next offering from Nike having partnered with HP, this time in the form of a track shoe. The Nike Zoom Superfly Flyknit, this shoe was designed and developed with sprinter Allyson Felix in the build up to the Olympics in Rio. Nike focused on three key areas Strength, fit and flex in order to maximise Felix's long powerful stride.

This outsole was again printed using SLS, allowing the shoe to bend and flex to the athletes foot. Selecting the optimum position of the spikes and removing any excess weight. Being a completely customisable process they were able to fine tune the design and reduce the prototyping stage drastically.

The metallic finish we see is a post processing finish applied to the SLS. It looks to be either a painted finish or an electro plating process. You can tell this as you are unable to see any build lines.

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Fast-forward to 2018 developments had started to make the first 3D printed marathon shoe, The London Marathon saw Eliud Kipchoge race in the Nike Zoom Vaporfly Elite Flyprint, the First shoe to feature a 3D printed upper.

This technology is known as SDM (Solid Deposition Modelling) a variant of FDM Printing. The process relies on a heated extruder to pipe a flexible filament (TPU) onto a flat surface which becomes the base for and structure of the print. Multiple layers are added to strengthen areas and only what is needed is printed resulting in a fast low cost print.

The image on the right shows the almost finished product. The extruder head works on a X,Y axis and covers a large area, this allows parts to cool and bond before more filament is added. These uppers still need to be lasted and bonded on a foam midsole but a very clever use of SDM. Allowing unlimited options when it comes to professional athletes with print times far faster than SLS printing and a fraction of the cost.