Dibakar Bandopadhya 1 International Journal of Recent Trends in Mechanical Engineering (IJRTME—ISSN: 2347 - 7326) Vol. 2, Issue. 2, April. 2014 An Intelligent Computer-Aided Assembly Process Planning Methodology for Mechanical Parts Dillip Kumar Biswal and Dibakar Bandopadhya* Abstract: An intelligent computer-aided assembly process planning (CAAPP) methodology has been developed that generates an automatic assembly sequence for mechanical parts. The proposed method is relied on knowledge based expert system. It can generate all feasible assembly sequences for complete assembling of a mechanical product from a given set of disassembled parts. A scheme for representation of the input data on the various constituent parts of the assembly is developed along with a set of knowledge based rules. Both techniques are developed for selecting the most suitable base part automatically taking into account of the various constraints. The method can generate all feasible sequences for assembling the various components together starting from a base part to the constituent part to the finished assembly. The proposed methodology is flexible, readily adaptable to the demanding assembling environments and also proves to be less time consuming. Keywords: Assembly Sequence Planning, Knowledge Based Expert System, Assembly Constraints, Base Part I. INTRODUCTION Assembling of mechanical parts is one of the key manufacturing activities to be found in almost every industrial sector. Yet, it is one of the most complicated and time consuming activities accounting for a large proportion of the manufacturing cost. As a result, there is much interest in reducing the cost of assembly activities. One way of achieving this is to improve the assembly process planning to determine the sequences in which parts of subassemblies are arranged together. Assembly process planning requires significant amount of expertise and experiential knowledge. This demand that the traditional product assembly sequence should be planned manually by an expert process planner with necessary skill and experience. ____________________________________________________________ Dibakar Bandopadhya, Faculty of Department of Mechanical Engineering, IIT Guwahati, Assam, India. Email: dibakarb@iitg.ernet.in However, manual process planning is highly laborious and time consuming activity that requires considering numerous constraints and large number of potential assembly sequences, particularly where complex assembly process is involved. Thus, essentially there is much interest in developing systematic and computer-aided assembly process planning techniques to automate the assembly sequence processes. Assembly process involves integration of components or parts sequentially to create a product to operate satisfactorily for a predefined function [1]. Generally assembly sequence planning consists of three main steps: assembly modeling, generation of all feasible assembly sequences, and optimization of assembly sequences [2]. The data for assembly sequence generation can be provided by the user or can be directly extracted from the CAD model of the product. Generally a typical product can have a large number of possible assembly sequences and can rise enormously with the increase in number of components [3]. However, due to assembly constraint the number is reduced significantly. In the past, various methods have been proposed by the researchers to generate assembly sequences. A question- and–answer procedure was developed, where questions are answered with a precedence relation between two components, to generate the assembly sequence [3]. Where, a liaison sequence graph (LSG) is used to represent the assembly sequence. Concept of AND/OR graph for compact representation of all feasible assembly sequences was also proposed [4]. An algorithm was developed based on case- based reasoning (CBR), to generate assembly sequence procedures [5]. Adjacency matrix methods were also used in Cartesian coordinate system to generate the assembly planning sequence [6]. Further, algorithm was developed and implemented using a LISP program to generate all feasible assembly sequence by considering the precedence relationship and combining the various subassembly operations [7]. A methodology was proposed to generate all feasible assembly sequences along three directions (X,Y,Z) in Cartesian coordinates system utilizing contact and translational functions [8-9]. Where, an assembly sequence table (AST) was developed to represent assembly sequence of the fit. A connector-based relation model (CBRM) was developed to generate a feasible assembly sequence [10], further two stages [11] and three stages [12] decision support procedure were also proposed to generate the parts subassembly sequences. Further, a mathematical model was developed to determine the optimum assembly sequence from the AND/OR graph of a mechanical product [13]. A web-based 3D assembly sequence system was developed as framework for customers to assist their design in decision