The focus of CIM is on information as it is the crucial element for integrating all the manufacturing activities. CAPP, as one of the key elements in CIM, needs to extract the manufacturing information such as machining features and precision specifications like surface roughness and tolerances from a geometric model in order to link CAD and CAM. However, these data are not real attributes of the geometric model in most of the current CAD systems. Therefore, human interpretation is inevitable for further processing of CAD model for downstream application like process planning or inspection. This paper proposes a scheme to represent the manufacturing information in a neutral format using STEP technology in order to enable downstream users such as process planner and inspection planner to make correct decisions on process selection, processing conditions, etc. It is shown that by using STEP AP224 manufacturing information encompassing machining features, surface roughness, dimensional and geometric tolerances can be completely represented together with part geometry, which certainly contributes to successful implementation of CIM.

Neutral representation of tolerance information for process planning using STEP AP 224

A recognition process of the features in a part model resorts to the knowledge of an application engineer. The knowledge is encoded as rules of the recognition procedure at the beginning that are applied to the part model during the recognition process. Such a human interaction is difficult to control in extracting the intended features because the intended features by the application engineer may change from one engineer to the other and the external situations. Instead, we treat the result of the recognition process as a rough extraction and allow the user interactively modify the result. In this paper, we present a feature recognition system where the user can inspect the result of the recognition and delete recognized features interactively.

H. Kang

Papers

A system for recognition and modification of machining features on prismatic components