Multiple material objects: from CAD representation to data format for rapid prototyping

The representations of contemporary CAD systems do not provide or contain a ny information with regard to the materials of the objects that the CAD sys tem is used for the design work. The information is usually supplied at the computer-aided manufacturing stage by the production engineers. With the a dvent of rapid prototyping (RP) techniques, which allow multiple material o bjects to be produced, this arrangement is inadequate. This paper proposes a scheme for representing multiple material objects in a CAD system. A mate rial tree of the object is built in the CAD system's data structure. By ext racting information from this material tree, and outputting a modified vers ion of a STL file format to the RP machines, multiple material objects coul d be fabricated in a RP machine. (C) 2000 Elsevier Science Ltd. All rights reserved.