Editorial
In recent years, there has been much debate about whether digital technology helps or hinders design creativity. CAD tools could be accused of limiting the creative freedom of designers since they can never be completely independent of their tools. Designers can sometimes spend more time thinking about which tools they should use rather than the shape they are trying to create. In addition, if the designer lacks detailed knowledge of the tools, the original design intent can be comprised to a simpler shape that is less difficult to achieve. Whilst manufacturing processes could only produce very complex shapes at a premium price, this may not have caused much of a problem. However, now the advent of rapid manufacturing (RM) promises to provide manufacturing processes that are capable of producing virtually any geometry with little or no cost and time differentials. Now designers have been challenged to create freeform geometry that really takes advantage of the freeform manufacturing offered by RM.
The main limitation on the complexity of digitally created geometry is the CAD modelling capabilities of the designer, either due to skills deficiency or software restrictions. For example, some conventional solid CAD systems can be more tailored towards creating regular, geometric shapes. The use of a computer-aided industrial design system may offer greater flexibility but even then, the complexity created is normally restricted to the outer surfaces of a product. A fairly new type of CAD system that offers almost unlimited geometry complexity is voxel-based “virtual clay” modelling. It enables the designer to create organic outer forms, textured surfaces, and structured interiors. It does this through the manipulation of 3D cells that represent small pieces of solid material. In recent years, virtual clay modelling has advanced in its capabilities and now offers many of the features of conventional CAD also. It can be used to translate 2D concept designs into 3D or indeed for direct creative expression within a digital medium. It can also be used to add complexity to shapes that have been created in conventional CAD. The combined use of virtual clay modelling and RM results in an exciting new environment for creative designers. They can work in a digital medium that mimics the flexibility of 3D physical modelling and yet offers the speed, repeatability and cost benefits of automated production. It could be described as “freeform design for freeform manufacturing”.
The most exciting use of this approach could be for the creation of highly complex personalised features within products. Conventional CAD struggles to cope with the geometric freedom that is required whereas the advent of virtual clay modelling seems to offer great potential in this area. Not only can the overall form be generated but highly texturised surfaces can be developed. It also offers new possibilities for medical applications where close fitting of complex human anatomy is required (for an example of this, see the paper by Bibb et al. in Rapid Prototyping Journal, Vol 12 No. 2). The benefits of RM-enabled product customisation are now well documented. Small production runs become feasible and complex geometry can be incorporated at no extra manufacturing cost. Using virtual clay modelling it will be possible to take product personalisation to a new level (perhaps even incorporating direct customer input). The current limiting factors appear to be the imagination of the designer and the capability of digital modelling techniques in supporting this. In future the latter restriction may well disappear. We can then await with expectation the new RM developments that unfettered designers' imaginations will produce.
Ian Campbell
