A METHOD FOR ASSESSING GEOMETRICAL ERRORS IN LAYERED MANUFACTURING - PART 1 - ERROR INTERACTION AND TRANSFER MECHANISMS

Geometric accuracy of components is one of the most important quality characteristics in layered manufacturing processes on which most rapid prototyping (RP) techniques are based. Layered manufacturing is an ap proximate fabricating process in which the final geometric error of th e physical part is affected, not only by the approximation technique u sed, but also by the fabrication process. Errors that occur in one lay er could propagate and transfer to other layers causing an accumulated error effect in the process. In this paper, a concept of disturbance error is introduced to describe the effect of accumulated errors in th e fabrication process. A physical model is presented to describe error interactions and error transfer mechanisms in the layered manufacturi ng process. A geometrical model is developed using surface approximati on techniques to describe the relationships of the geometrical errors. It is shown that although the complexity of the part geometry is not directly related to the manufacturing process, it will affect the geom etrical errors of the part produced.