Rapid prototyping scores well on all fronts

The term mass customisation stands for the idea of creating bespoke products in the price range of competitive, mass-produced products. This target can be achieved with the help of IT. To a certain extent we are already using the technology. The same concept can now be applied to three-dimensional products using the possibility to drive manufacturing from 3D CAD data. One creates a basic design of a product - equivalent to the basic letter, or in 3D, a basic design of sports shoe outsole. The personal data is then integrated - for example the shape of a foot and the name of a person. Finally, the two are linked as in a mailing to produce the individualised outsole by laser sintering, with the person's name already written into it. For Prior2Lever (P2L), laser sintering was the last missing link in the puzzle to make their business idea fly - the production of bespoke, high performance footwear for professional athletes. The vision of the founders is to allow for individualised, functional footwear to improve performance and at the same time to prevent injuries. The company has harnessed layer-by-layer fusing of plastic powder in an EOS laser-sintering machine to manufacture the soles of the bespoke boots. One leading Premiership player has already benefited. The individual, who has to remain nameless due to legal reasons, underwent an operation in 2003 for a foot injury and was subsequently injured several more times. Since wearing the P2L boots he has noticed an improvement in performance and is back training and competing for a first team place. P2L will also be working closely with Olympic medallists and hopefuls in a number of different disciplines. The unusual name of the bespoke footwear manufacturing company hints at the manufacturing process. It starts with the first director, Trevor Prior, consultant and podiatric surgeon and an internationally renowned foot and biomechanics expert who treats many Premiership players. Prior assesses players at his London-based clinic using special insoles fitted with force sensors inside test boots to check for anomalies during standing, walking and running. This is to identify the optimum position for the person's feet for any given sport. By scanning a sequence of plaster of Paris casts of the feet, which are more accurate with each iteration, orthoses are prepared and tested. Finally, each foot together with the orthoses, is digitally scanned. The resulting point cloud data is passed to Mr Prior's colleague, creative director Greg Lever-O'Keefe, who holds a masters degree in performance sportswear design at the University of Derby and whose PhD dissertation will be based on this work. He converts the data into a solid CAD model, which in turn is used to CNC-machine a wooden or plastic last around which the boot is made. The top part of the CAD model is flattened and post-processed to laser-cut the leather upper, which is stitched to the bespoke outsole that has been laser-sintered. This outsole is the secret ingredient in the recipe. Starting from a basic design, the important functional areas are adjusted in the CAD design, such as the orthotic shape on the upfacing side and the flex zones, according to the individual foot's needs or the position of the cleats. The thickness of the sole varies in different areas, according to the weight of the player and the amount of flex required, at the same time providing excellent overall load distribution - much better than with a standard TPU (thermal polyurethane) football boot sole, which is overly flexible across the entire surface, including in all the wrong places. Tests involving cantilever flexing of laser-sintered soles to 45 degrees for 500,000 cycles showed no stress cracking, but the current beta tests in training are needed to check performance under conditions of greater flexing, lateral movement and impact. Initial tests have proved very successful. Third director of the P2L team is Volker Junior, a consultant for technology integration specialising in layer manufacturing and mass customisation strategies, who brings commercial expertise to the business as well as a wealth of knowledge in laser sintering. Collaboration between P2L and the Munich company is close, with all outsoles to date made in the EOS demonstration area using files sent from the UK. Similarly, Greg Lever uses the CAD support services and consulting support of Freedom of Creation, Amsterdam, a pioneer in the design for products produced by layer sintering. Before opting for laser-sintering, Lever looked at different ways of producing bespoke outsoles in small volumes of, say five- to 10-off, under a Sports Science Engineering and Technology (SET)-funded research project co-directed with Dr Neil Hopkinson of the Rapid Manufacture Group at Loughborough University. A possible route is to CNC mill the soles directly from plastic by applying CAM software to create cutter cycles from the CAD model. One problem is that the plastic tends to burn, and another is that the complexity of the shape requires 5-axis milling, which is expensive. Another technique investigated was to produce an aluminium injection mould, but again, the cost was too high for such a small batch run and lead time was too long. As to the future, P2L will advance its product in several different areas. The target is to further and fully exploit the 'freedom of design' that comes with the use of a layer manufacturing process. In the area of outsole design, that means for example to build in honeycomb structures to dissipate the forces generated by running, which are up to five times body weight and a major cause of injury and arthritis. In time, the technology could enter mainstream sports, with diagnostic equipment and foot scanners in high street shops downloading data to a laser-sintering machine to allow mass customisation of footwear. Such a scenario is already a reality in lighting and furniture, albeit still at the exclusive end of interior design. For the time being, the forthcoming intensive testing of P2L boots by selected players will allow product development to be finalised. Time to market is crucial for success and the next World Cup is coming soon.