Today's manufacturing systems are striving for a integrated manufacturing environment. Large scale applications of computer based technologies have given rise to classical problem of 'Islands of Automation' and lack of information integration. This paper aims at providing a framework for integrating these islands based on an Integrated Process Planning Model (IPPLAN). This integration will provide a common platform for integrated decision making and real time response to the dynamic shop floor conditions. Key functions like scheduling and process planning is considered as prime candidates for integration. A tolerance analysis based process planning model is also proposed as a part of the integrated system. We will also show how tolerance analysis will increase flexibility of the process plans and improve the real time response.