The rapid advancement of information technology and its integration with the manufacturing technology increased the necessity of consistent and coherent data flow in the chain of Computer Aided Design (CAD)-Computer aided Manufacturing (CAM)-Computer Numerical Control (CNC). To achieve this, ISO 10303 standard (STEP), developed by ISO, is seen as a solution since STEP is independent of the environment on which design data, manufacturing data or machining data produced. In this thesis, efficiency of NC-code generation, with the inclusion of process planning data, from a STEP based CAD data is investigated. For the investigation purposes, software responsible for both building the STEP based CAD data and generating related NC-code automatically is developed. Using this software, several parts are designed / generated NC-codes are verified via CNC simulators and some test parts are produced. STEP AP224 based feature modeler, developed specifically for 2- axis rotational part design, includes / feature library, feature modeler employing SW2007 via API for visualization and preprocessor responsible for generation of STEP file in neutral format, called STEP Part 21. The NC-code generator includes / postprocessor responsible for STEP Part 21 interpretation, CNC machine tool and cutting tool database and preprocessor responsible for NC-code generation.

The implicit and low-level part definition data, provided by geometric modeling cannot be used by downstream applications. Therefore, feature based modeling concept has been introduced to integrate CAD and downstream applications. However, due to the lack of implicit and explicit standard representations for features and unmanageable number of possible predefined features without standardization, feature based modeling approach has proved to be inadequate. STEP AP224 provides a standard for both implicit and explicit representations for manufacturing features. This thesis presents STEP AP224 features based modeling for rotational parts. The thesis covers features extracted from STEP AP224 for rotational parts and their definitions, classifications, attributes, generation techniques, attachment methods and geometrical constraints. In this thesis a feature modeler for rotational parts has been developed. STEP AP224 features generated are used as the basic entities for part design. The architecture of the proposed system consists of two three phases: (1) feature library, (2) feature modeler and (3) preprocessor. Preprocessor responsible from STEP-XML data file creation. The data file created can be used in the integration CAPP/CAM systems without using a complex feature recognition process. An object-oriented design approach is used in developing the feature modeler to provide incremental system development and reusability.