Prototyping faster, cheaper and virtually

With the advent of solid modelling and rapid prototyping technology, many pundits were, and still are, asking whether traditional physical prototypes would soon be ancient history. The short, glib answer is no, but their numbers are decreasing quite markedly. As with all CAD/CAM and PDM (product data management) system market generalisations, much depends on your industry sector and how much of your design process actually revolves around the evolution of a prototype. Some product design activities rely on simplified prototypes to prove out theories much more than others. In some industries, like boat building, the last physical prototype is in fact the first production model. Also, life in engineering is rarely ‘black and white’; some functions or parts of physical prototypes that were made by model makers in the past, are now rapid prototypes or vacuum castings, themselves made from rapid prototypes. A short answer should really be that, because of new technologies, physical prototyping has changed significantly – as have the design processes necessary to produce it. To confuse the issue even further, now that PLM (product lifecycle management) as a packaged system is becoming a reality, there is a need to prototype the process as well as prototyping the physical product. Far from being marketing hype, prototyping the process at an early stage can provide huge business advantage. As Andy Reilly, world-wide design leader for IBM, says: “Prototyping the process actually gives you a view of the impact of a new product development project on the whole enterprise, as well as providing an essential cost model.” One well known child car seat manufacturer that didn’t want to be named, for example, is implementing a strategy with IBM for designing products specifically based on processes. “Their fundamental issues are not only about design, but design to increase innovation,” says Reilly, “because their biggest competitor is their own last year’s model!” In that company’s terms, new product introduction is all about product evolution against a framework of all its process requirements. It may design a new product every three years, but the retailers will try and drive the price down every year. As a design company, it has to innovate continually in order to meet these commercial pressures – so the cost model is important. Similarly, in the automotive industry the greatest contribution in recent years to the quest for the 24 month developed car, has been the increase in computer integration in the design processes, allowing the inclusion of computer-aided styling and the introduction of review and ‘sign-off’ of ‘virtual’ prototypes. Photo-realistic renderings are produced during styling to check the visual qualities of the vehicle, and while these images alone are unlikely to be enough to get a body design approved, they may well be sufficient to get one rejected, which saves the time and expense of building that physical model! Virtual sophistication The simplest animated images are ‘turntable’ sequences, which simply show the vehicle rotating. A more sophisticated animation might show the ‘virtual vehicle’ travelling down a virtual road, complete with reflections of trees, horizon and nearby buildings. Some companies are using ‘immersive’ virtual reality environments (like ‘caves’) that allow controlled dynamic viewing, full size and in real-time. But the computer resource required to achieve that is truly immense. Automotive stylists at GM, together with CAD software giant EDS, have pioneered the development using Unigraphics in the whole design process. Any computer model that considers aesthetics alone is viewed there as a waste of time, because it will need to be rebuilt when other clear engineering requirements come to be satisfied. But done properly, early adopters of ‘aesthetic engineering’ have shown that they can save up to 20 weeks in the styling process alone. The real trick is to model once, not many times, which reduces the overall design process, shortens product development time, and ensures that the industrial designers retain control over their designs. Pitney Bowes UK, the document handling company, took a more classical rapid prototyping approach when it acquired an SLS (selective laser sintering) machine from RP technology leader 3D Systems. Chris Ramm, Pitney Bowes’ tool room manager, says: “Modern rapid prototyping processes need to be in place because time-to-market is so critical. Modern RP technologies allow us to produce components very quickly… The actual production of prototypes is so much quicker than it was even five to 10 years ago: [down] from two weeks to two days in some cases.” Having a rapid prototyping machine in house can clearly have a big positive effect on the design process. As Ramm says: “There is no substitute for having the component in your hand as you are trying to refine it. From a designer’s point of view, to be able to design it today and hold it in your hand tomorrow is invaluable.” But there are also some hidden benefits. “We don’t have to negotiate with a rapid prototyping bureau, or raise purchase orders, or do any kind of back-office administration to get parts,” says Jim Webster, Pitney Bowes principal production engineer. “The visible payback was achieved in about 12 months, but if you include all the invisibles ... ROI (return on investment) would be more like nine months.” Pitney Bowes uses its SLS machine in the very early days of product development. “We produce the whole machine made from SLS parts for functional testing,” explains Ramm. “It gives us the basic design concept model which we can test in ways not possible before.” Then for final tooling the firm sends both CAD geometry and the rapid prototype to the tool maker, again to help speed up the process. “By looking at the rapid prototype, an experienced mould maker can provide a lot more feedback more quickly than having to review drawings or data translation files,” says Ramm. ‘Prototypes’ in real production Meanwhile, the latest rapid prototyping technology is advanced digital manufacturing (ADM), where RP parts are used in the finished product itself. “Renault F1 is examining the feasibility of using ADM parts on the race car,” says Graham Lindsay, 3D systems’ UK country manager. “The availability of JIT (just in time) rapid prototyping parts means that limited production car makers, like Rolls Royce or Bentley, can actually manufacture custom dashboards to order.” In a similar endeavour automotive Tier One supplier Delphi Diesel Systems is currently investigating ‘design for rapid manufacture’ of batches of small parts with a view to semi-mass production of plastic parts without using any tooling. As Paul Smith, senior design engineer at Delphi, says: “This removes all the restrictions of the manufacturing process from the design of the part, with no necessity for split lines or draft (which can affect the shape of the part).” Plainly, far from eliminating the traditional craft of the physical prototype, rapid prototyping has changed, and is continuing to change, the whole approach to prototyping. It has introduced new technologies and evolved into different processes for limited run manufacture that can be extremely beneficial. And as well as cutting time to prototype and time to market, the ROI for in-house rapid prototyping machines is about the same as for machine tools. Progress indeed.