Cover story: Designing differently

One of the greatest difficulties when looking at the subject of rapid manufacturing is finding a term for it upon which everyone agrees. Rapid manufacturing; additive fabrication; additive layer manufacturing; 3D printing; direct digital manufacturing – all these and more are terms for what is essentially the same thing: the manufacturing of production parts direct from CAD data via the building up of layers of plastic or metal. Of course, there is more to the various processes than that. Indeed, given that there are at least 25 different rapid manufacturing technologies, it is easy to understand the confusion over nomenclature. Of course, when they first appeared, these additive manufacturing techniques were exclusively designed for prototyping purposes. Indeed, as such, they became grouped under the umbrella title 'rapid prototyping'. However, as the technologies have matured, it has become clear that there is more to these methods than just prototyping. Increasingly, it has become possible to produce small series of components using additive manufacturing. So, given that (according to some) the technology has reached the ripe old age of 21, has it yet come of age as a manufacturing technique? The advantages offered by additive manufacturing are clear enough. The first and most obvious is the total elimination of tooling costs. Equally, only the energy necessary to form the part is expended, while waste is virtually eliminated, as since the process only forms the desired part, there is almost no waste formed. The absence of waste enhances energy efficiency, as energy is not used to transport or dispose of waste. Speed is another benefit because, although the actual 3D printing process is far slower than traditional techniques, these often require ancillary processes and procedures to form the final product. 3D printing technologies eliminate these steps. Considering this, products can be brought to market faster and sometimes cheaper by using 3D printing rather than traditional processes such as castings and forgings. Since no special tooling is required, 3D parts can be built in hours or days. From a design point of view, however, the single most exciting factor is surely the ability to create highly complex geometries. Additive manufacturing technologies allow the creation of more efficient designs without the limitations imposed by other processes. For instance, internal passages and features can be created that would simply not be possible with conventional methods. Naturally enough, it is this last fact that really excites the imagination. As Klaus Müller-Lohmeier, Head of Advanced Prototyping Technology at Festo puts it: "This is a paradigm shift in design and manufacturing. These technologies will allow us to move from manufacturing-driven design, where the design is dictated by the manufacturing techniques, to truly design-driven manufacturing." As a company, Festo has made a significant investment in rapid manufacturing technology, having been active in the field for 15 years. At the 'Fast Factory' at its Esslingen headquarters in addition to laser sintering, three other procedures are used: laser melting for metals such as aluminium with an EOS Formiga P100 machine; fused deposition manufacturing or FDM for polymer products with a Stratasys FDM machine; and wire cutting. Plastics processing experts predict a bright future with laser sintering or FDM: "In five years, these procedures will probably be standard," explains Müller-Lohmeier. The investment in the new Festo Fast Factory has paid off. Klaus Müller-Lohmeier explains: "We use rapid prototyping in research and development, particularly to reduce the initial sampling time for moulded parts. Ultimately this reduces the overall development time and the products' time to market." However, Festo can also produce individual components in small series rapidly and relatively economically through savings in tool costs. The procedures are also persuasive in direct customer contact situations: "We can create sample components faster to discuss special designs with customers and offer alternative solutions," explains Müller-Lohmeier. Communication patterns for customer contacts or initial sampling parts can therefore be created almost overnight. Now only 60 % of products manufactured using generative methods are internal developments. 40 % already go straight to the customer. "For some of the orders placed, the Festo Fast Factory was even the deciding factor as customers were impressed with the technological leadership of the Festo Fast Factory," explains Müller-Lohmeier. The Fast Factory now produces 20,000 parts per year and meets 1,000 orders. As Müller-Lohmeier puts it: "For such a new technology, we are at a high level of production." One of Festo's most high-profile examples of rapid manufacturing was the bionic FinGripper, which is used on its 'elephant's trunk' robotic handling assistant. The gripper based on a fish fin, was created cost-effectively using the selective laser sintering procedure. 0.1 mm-thin layers of plastic powder are piled up on a platform and each individual layer then melted by laser into a fixed component. This reduces its weight by 90 % compared with a traditional metal gripper, allowing it to work energy-efficiently. For 150 FinGrippers, Festo needed a production time of just 24 hours following receipt of the internal order. Another keen advocate of the possibilities offered by these technologies is Paul Gray, Manager – Advanced Manufacturing technologies for Parker KV. Gray has advocated the increased use of advanced manufacturing technology for many years now. He argues that one of the factors that has held the technology back from more mainstream acceptance has been the familiarity with it as a prototyping rather than a production technology. He says: "Its background is as a prototyping tool and that's the problem – people haven't yet made that leap. Given that, it takes guts to say "I'm going to use this technology for manufacturing'. I've always been prepared to make that leap of faith because I believe in this technology." However, he believes the big challenge will be based around design. "People are going to have to learn to design differently," he says. "You will be able to design to function rather than form. That's a positive thing, but it's also a challenge. You're going to have to be able to design into a space – thinking in 3-D – and that's something people have a lot of trouble with." Tim Heller of Stratasys, also sees the shift in design mentality as being an obstacle to the widespread acceptance of additive manufacturing. "The design rules are changing," he says. "Certain groups of people are always going to be early adopters, but this technology is outside a lot of people's comfort zone, which remains focused on traditional manufacturing techniques." However, Heller suggests that this could be a generational issue as much as anything, saying: "It could just be a case of the generations shifting. This is a computer generation that is likely to be more comfortable with the concept, particularly as design engineers are being exposed to additive manufacture younger and younger as the technology is used in more and more schools." This generational issue is one that Paul Gray also acknowledges, saying: "I can understand why people don't make the leap. After all, when you're a younger engineer, no-one listens to you and when you're older, you can't be bothered or don't want to take the risk." All of which begs the question of what the future holds for these technologies. Gray is unequivocal, saying: "I believe rapid manufacture is the future of manufacturing. In a few years time, we'll have these in our houses. I can see the day when rapid manufacturing replaces stores, as you'll be able to download the design, press a button and there it will be." Heller is bullish when asked when he believes the technology will 'go mainstream', saying "It depends what you mean by mainstream. We've already sold 11,000 additive manufacturing machines worldwide! But I'll bet you that within 5-10 years, there'll be service bureaus everywhere using additive fabrication. In 20 years, you'll go into any machine shop and see our types of machines making widgets." Klaus Müller-Lohmeier believes the word still needs to be spread, saying: "I wish [rapid manufacturing] would become mainstream faster. The problem is that most people simply don't know about these technologies. Every week I speak to senior CEOs and do guided tours for them and am always struck by the fact that these people simply don't know about these technologies. So there is still some missionary work to be done." Of course, considerable obstacles to additive fabrication's general acceptance as a manufacturing technology still exist. One of the key ones is the range of materials available, a fact Paul Gray bemoans: "The materials aren't developing fast enough. Plus, they are too expensive and there is a tendency to try and force you to use the materials provided by the machine manufacturers." These cost of ownership issues, he believes, tend to scare people away from the technology and can even have a detrimental effect on quality. "People sometimes recycle material to save costs and quality drops as a result. In turn, that leads people to think that the process is no good," he says. Says Tim Heller: "There's no denying that the palate of materials available to – say – injection moulding is greater than that available in additive manufacturing. However, it's not as much as a limiting factor as some people think. New materials are becoming available all the time. We're always working on new materials." The speed and extent to which rapid manufacturing comes to prominence as a manufacturing technique remains a question of guesswork for the time being. However, there can be little doubt that it is on its way sooner rather than later and that its impact for design engineers is going to be revolutionary. As Klaus Müller-Lohmeier puts it: "Additive manufacturing eventually means the liberation of design from manufacturing"