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

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