Application of an innovative technique on aircraft piston engine

Modern 3D CAD permanently modifies the development process of most industrial products. The traditional approach, in which it was necessary to design the components in short time to build the prototype in order to make assembly/functional/structural/durability tests, is no more necessary even for complex systems. The old "Lean thinking" appoach based on the brain storming is not so far applcable on the complex systems in which it is imossible to estimate the best solution without an extensive design process. In the old days, it was sayd that the 90% of the exceeding costs on product development were determined during the first 10% of the project. All these old ways of thinking are typical of an anachronistic vision of the design project approach. In facts, nowadays, due to the possibility of virtual testing, the design has to be optimised by the CAD/CAM/CAE methods, then in its final phase it has to be experimentally tested and produced. In this field a new technique of modelling, rototyping and manufacturing is introduced in this paper.A very simple two axis CNC machine is used to manufacture a polystyrene foam model of the cast parts. The lost foam technique is used to obtain high quality cast parts, a resin mould for sand casting or the metal dies. This technique makes it possible to obtain immediately a physical 3D mock-up of the part, which can be directly taken in the foundry or can be used in the design office and in the prototype shop to check for correct design. Modifications and improvements are easily implemented. This 2D sections-lost foam technique can be used also for serial production. The method is convenient for serial production up to 300 pieces per year with Italian labour costs. For more numerous productions other techniques should be used. However, also in this case, the foam model is useful for the final design of high-number production tools