An innovative procedure to update moulds CAD model with the real geometry using Reverse Engineering

Modern CAD/CAM techniques together with 5 axis high speed milling allow to reduce moulds manufacturing time and costs. Nevertheless, in order to use the moulds, operations of manual finishing and fitting are still always required. Such operations, performed manually by mould makers, modify milled surfaces of the moulds. Changes in the product's shape are sometimes decided after the mould has already been machined. In such cases, if it's possible, the mould maker modifies directly the mould. The final real geometry of the mould does not coincide with the one of the original CAD model. The aim of this paper is to define a procedure, based on Reverse Engineering methods, to reconstruct and to update the mathematical model of the mould after it has been polished and fit. The procedure was tested on a mould for the production of a camera body. A zone of the mould was manually polished and an aesthetical change, not included in the original CAD model, was introduced on it directly. The mould was digitized with an optical system based on structured light and the point clouds were treated with a software for the reconstruction of the surfaces. After updating the CAD model of the mould, a conceptual prototype of the camera shell was created to appraise on the final product the aesthetical change directly introduced on the mould.