10 - Process Planning in Design and Manufacturing Systems

Abstract

Process planning can be defined as the task which determines how a part should be manufactured according to the design specifications. The process planning is usually performed manually by an expert process planner who examines the engineering drawing and determines how to manufacture the part based upon his manufacturing knowledge and expertise. In order to avoid the disadvantages of the manual approach and to bridge the gap between computer aided design (CAD) and computer aided manufacture (CAM), computer aided process planning (CAPP) systems have been developed to automate process planning activities. This chapter discusses CAPP systems. The ultimate goal of CAPP is to develop process plans for components without human intervention. Traditionally two main approaches of CAPP are recognized, namely the variant approach and generative approach. Variant process planning is basically a computer assisted extension of manual process planning. The generative process planning approach utilizes an automatic computerized system which consists of decision logic, formulae, and knowledge used by process planners to produce process plans. Unlike the variant approach standard process plans are not required. An extension of generative approach is knowledge-based generative process planning. An expert system or knowledge-based system from artificial intelligence (AI) seeks to emulate the reasoning capacity of an expert in a particular field. Expert system techniques are considered to have the largest potential for the capture of experience and decision logic for the development of CAPP systems.