RAPID PROTOTYPING & RAPID TOOLING
In the world of design what often gives rise to substantial changes in thinking is the modification of producer needs, a consequence of a modification in market demand. The latter, as I have already written on these pages, is made up of people to whom the producers turn and whose needs stimulate the change. It is said that the market is always in evolution and the truth is that it reflects, more today than in the past, the growing globalisation that has led to an exchange of products from one country to another with the attendant contamination, in a positive sense, of different cultures. This situation has become more and more emphasised since the end of the last century. Beyond this sociological analysis (this too important when we speak of Industrial Design) the consideration we might make is that this context has led to a fragmentation of production due to the need to satisfy various or customised needs, and therefore the frequent manufacture of small series, produced under strict time-frames. To meet these new needs technology has given us some very interesting tools that are called: Rapid Prototyping and Rapid Tooling. With the term Rapid Tooling we intend a combination of processes that produce models and components by adding material layer by layer, beginning with a three-dimensional mathematical model. Differently from all the traditional machines that function by successive subtraction of material from a block in which the shape to be obtained is contained, R.P. systems manufacture successive layers of material consisting at times of liquids, dust, wires or laminates. Layer after layer, these machines re-construct the object that represents the mathematical model of departure. For this reason such production technology is also known as Layer Manufacturing. This is innovative technology which renders possible the production (in a few hours and without the addition of special tools or equipment) of objects even of complex geometry, directly from the mathematical model of the object produced on a three-dimensional cad system (solid modelling). From this pioneering idea of Charles W. Hull starting in 1982 was born 3D Systems Inc., an American company which is the leader in the sector, while five years later the first apparatus for stereo lithography was born, the SLA-1. The presence of capillary CAD systems gave an extraordinary push to the search for ever new and different methods, aimed at the production of objects starting from an electronically-defined geometry. From the research, however, were born and consolidated other technologies such as selective laser sintering (more briefly, SLS) fused deposition modelling (or FDM), laminated object manufacturing (LOM) and many others. There are many R.P. systems, about twenty of them, and they adopt different systems to achieve the production of the prototype. These involve a series of passages that we can identify as follows: 1) Modelling with a 3D cad from the object for solids or surfaces, 2) Transformation of the cad model into stl format. 3) Reading the stl file using the software of the R.P. machine, followed by the orientation of the stl model, the creation of the supports (depending on the technology). 4) Slicing (operation common to all the various technologies which consists of the intersection of the complete or incomplete model between supports, depending on the technology, and a series of layouts that normally is parallel to the guidance for the manufacture of the model. Slicing varies currently according to technology and needs between 0.05mm and 0.7mm. 5) Physical construction of the prototype on the R.P. machine. 6) Removal of the cleaning supports and manual finish of the prototype. None of the current R.P. systems allows us to obtain a prototype in definitive material or produced with technologies similar to those that will be then used for real production. To be able to achieve Rapid Manufacturing it was necessary to study other techniques and therefore greater interest was paid to Rapid Tooling. These are those techniques that allow the rapid production of equipment and the calibration of processes that permit the production of pre-series, with definitive characteristics, starting from an object made by R.P. The advantages are notable and range from the reduction of time-frames and production costs of prototypes and the consequent containment of time-to-market, to the possibility of producing pieces with complex shapes (with cavities, undercuts and profiles that are difficult to obtain by traditional mechanical means). The limitations exist in the types of materials to be used. What is very important is the possibility of correcting errors that the cad designer was unable to eliminate and which are normally corrected only at the advanced development phase of the product, after the production of the pre-series or already in the pre-production phase with heavy economic costs. In addition there is a change to evaluate the functionality of the product, making modifications judged necessary and perhaps choosing from among different alternatives even in the design phase, having the immediate availability of the prototype. Rapid Prototyping and Tooling techniques will play an ever more determining role in the new millennium toward the development of new products and their relative equipment. In an era of globalisation of markets the ability to offer reduced development and production times is the new and stimulating objective for our companies. Various industries here in Friuli have already adopted Rapid Prototyping tools. Tonon s.p.a. of Manzano has recently adopted this technology to give greater impulse to its constant research. These innovative technologies represent the glue between the various development phases of the product such as design, 3D CAD, the definition of the equipment and the production of pre-series and therefore are from now on an important support for designers and for the producer, who may concretely and rapidly evaluate the fruit of their research and then make any necessary modifications to the final product.
Prof. Fabio Di Bartolomei
Industrial & Interior Designer
Design Professor at the Cignaroli Academy of Fine Arts of Verona Former Design
Professor at the Architecture Faculty of Trieste