Computer Aided Process Planning Research Articles

Fuzzy-set-based approach for concurrent constraint set-up planning

Material removal processes are integral parts of many manufacturing systems. They are either primary machining processes or an important part of preparing toolings for subsequent forming and moulding processes. Manufacturing process planning identifies the type of material removal processes and the machining parameters, cutting tools and fixtures needed to generate the features on a part. Previous research in manufacturing process planning has concentrated mainly on the role of features, in the derivation of the associated process and fixture plans. Many computer-aided process planning (CAPP) and computer-aided fixture planning (CAFP) systems derive process and fixture plans from the features on a part, on the basis that these features are context-free. However, manufacturing operations are interdependent processes. In the author's computer-aided set-up planning (CASP) system, a different perspective is adopted. Feature relations form the core of the conceptual structure. These features relations, which are often imprecise, are used in deriving set-up plans. The feature relations, which may be due to geometrical constraints, tolerance requirements, etc., are modelled using fuzzy sets and fuzzy relations. This paper presents the various feature relations considered in the present system and proposes a practical planning algorithm for set-up planning.

Product and manufacturing capability modelling in an integrated CAD/process planning environment

Computer-aided process planning (CAPP) is one of the key components in computer integrated manufacturing (CIM) environment. Fully automatic CAPP systems require information transfer between CAD/CAM systems to be mutual, dynamic, concurrent, automatic and efficient. The difficulty in achieving this is the management of the vast amount of heterogeneous data, knowledge and complicated inference processes encountered in developing automatic planning systems. The objective of the reported research is to develop a framework for modelling and managing engineering product and manufacturing capability information in an integrated feature-based CAD/knowledge-based process planning environment. The feature-based design system is developed with a commercial boundary representation (Brep) solid modeller with additional feature-modelling functions. The process planning system is developed using a knowledge-based system, which is fully integrated with the design system through an information mapping mechanism. Process planning decisions are made by searching for a match between the product requirements and the process capability of available manufacturing systems. This is achieved by invoking the rules coded in an inferencing mechanism (an inference engine). Both the underlying methodologies and the implementation aspects will be addressed in this paper.

Process planning with genetic algorithms on results of knowledge-based reasoning

The paper presents a new approach to solving even unusually complex problems of computer-aided process planning (CAPP). Main principles are based on the analysis of the roles and relations of CAPP in advanced manufacturing systems. Planning is carried out in several stages, by using both domain-specific knowledge and domain-independent, general methods. First, by knowledge-based reasoning, repertoires of plan elements and technological constraints are created that the final solutions must meet. Then, a global plan merging process generates plan variants so as to meet the given optimization objective. Among the various plan merging methods, one using genetic algorithms stands preeminent by its performance and robustness. Domain-specific knowledge, methods of reasoning and plan merging are described in detail.

A CAD/CAPP interface for complex rotationally symmetric parts

Abstract A new methodology for interfacing Computer-Aided Design (CAD) and Computer-Aided Process Planning (CAPP) based on automatic feature recognition is proposed in the domain of complex rotationally symmetric parts. The interface system consists of three stages: (1) Initial Graphics Exchange Specification (1GES) data translation, (2) polygonal decomposition or splitting, (3) automatic recognition of precedences and features. In the data translation stage, 1GES data are transformed to multi-sectional chains of the upperhalf profile of a part and a raw stock. For the raw stock, not only a box shape but the non-rectangular one is also considered. In the polygonal decomposition stage, the removal volume is decomposed into a data structure of a Pseudo-polygon (Pgon). The Pgon data structure based on the surface classification (real, virtual, partial, and embedded) is suggested as a new feature representation scheme. In the automatic recognition stage, the geometric precedence relationship between Pgons, is automatically recognized, and then structured globally into a precedence tree form. The feature class and instances are automatically identified from the decomposed Pgons.

Tolerance analysis in setup planning for rotational parts

Abstract Tolerance analysis is crucial in process planning for precision manufacturing; however, very few computer-aided process planning (CAPP) systems are capable of performing tolerance analysis. At most, tolerance analysis is used to check the dimensional tolerance stackups rather than generating optimal setup/process plans. Recently, some researchers have begun to recognize the importance of tolerance analysis in generating appropriate setup/process plans. Although some rules of thumb have been developed for automated setup planning, no systematic approach is available in the literature. In this paper, a graph-theoretical approach is proposed to generate setup plans based on tolerance analysis. The design specification of a part is represented as a graph. The problem of identifying the optimal setup plan is transformed into a graph search problem. A setup planning algorithm for rotational parts is then developed and implemented. The algorithm is evaluated using Monte Carlo simulation and found to be effective. The graph-theoretical approach is very useful for solving the setup planning problem. The advantage of the approach is that it is a mathematical approach and can be easily evaluated, modified, and computerized.

A Prospective Scenario for Integrated CAD & CAPP

Abstract The aim of this paper is to introduce an intelligent manufacturing oriented design system kernel, intended to be customised for several design applications, which has been called the Meta Model for CAD (Computer Aided design) and CAPP (Computer Aided Process Planning). In a first section, the set of problems and experimented solutions of two aspects of the integrated design and manufacturing planning process are shortly described. In a second section, the models and functions of the meta model are introduced and detained. In a third section, the manufacturing planning aspects is addressed.

A Group Technology-Based Modelling Approach to Computer Aided Process Planning

This paper reports on the design of a computer aided process planning system (CAPP-GT) for the parts manufactured in a group technology cell. The software incorporates various modules for part families description, sequence modelling, rule based tool selection, statistical model for time estimation and finally for report generation and editing. All this modules are built around a technological data base and a knowledge base formalizing the group technology cell experience.

Studies on process plan representation in CAPP systems

Process planning establishes the methods and means of converting the raw material into a finished part. The planning function interacts with the manufacturing system through (a) the design specification, (b) manufacturing resources, and (c) the process plan. Similarly, computer aided process planning (CAPP) establishes the links with its application environment through the analogous models. Though much attention is paid to the modelling of the part and manufacturing resources, modelling of the process plan has been an ignored topic to-date. The present paper discusses the need for modelling the process plan, and proposes a framework for process plan internal representation (PPIR) for the effective integration of CAPP and CAM functions. The implementation of the proposed framework in GIFTS — a CAPP system for rotational parts — is also discussed.

Automated tolerance analysis for CAPP system

Various computer-aided process planning (CAPP) systems can produce different process plans, but few of them can deal with the specified design tolerances that have a significant influence on the process selection, machine selection, set-up and datum selection, operation sequencing, cutting condition decisions, and time and cost calculations; nor can they provide exact information on fixture/datum and the coordinates of the tool movements that are the necessary data for automated NC programming. The focus of this paper is on the discussion of an automated tolerance based analysis approach of CAPP systems.

Computer aided process planning (CAPP) for electric discharge machining (EDM)

This paper deals with the development and implementation of an interactive process planning system based on generative approach for die sinking type Electric Discharge Machining [EDM] operations. The system has been divided into three modules. The module for management of machine tools database updates the database according to the availability of machines for use. The component representation module identifies features interactively. The planning module combines features for simultaneous machining, selects machining parameters, sequences operations and selects machine tool which will be able to physically accommodate the component and give maximum utilization of its power. The process plan generated is displayed to the user and is also stored in a file with part number as its key.The proposed system intends to reduce the skill required by a process planner. It decreases process planning time, resulting in increased productivity. The system has been implemented on HP-9000/950s supermini-computer with UNIX operating system using ‘C’ language (HP-C).

Framework for development of CAD/CAC systems

This paper provides a framework for the development of Computer-Aided-Design/Computer-Aided-Construction (CAD/CAC) systems. A description of the proposed CAD/CAC systems is provided. The proposed system contains software tools related to (1) conceptual design, (2) structural and foundation analysis, (3) design of structural components, (4) routine geometric, mathematical, and optimization functions, (5) construction management, (6) Computer Aided Process Planning (CAPP), (7) process simulation, and (8) constructability analysis. On-going research work in areas related to CAD/CAC systems are highlighted. Incorporation of Group Technology (GT) paradigm for civil engineering structures to enhance the efficiency and effectiveness of the proposed systems is investigated. Issues related to algorithm development are also discussed. Possible extension of Automatically Programmed Tools (APT) language to include construction industry processes are examined. Specifically, the programming level syntax of APT can be extended by adding construction related vocabulary and features to only two out of five statement types and processor-level syntax can be extended by incorporating additional modular features.

Data extraction from geometric models for process planning for parallel machines

Process planning bridges the gap between design and manufacturing. In computer-aided process planning (CAPP) systems, the goal is to automatically extract data from a design model and use it for generating plans for manufacturing. The extracted data should correspond to the type of machining process under consideration, and the extraction techniques must work with the computer-aided design (CAD) model representation. We consider manufacturing information/data extraction from geometric models for parallel machines, particularly mill/turn machines. These are a new class of powerful numerically controlled machine tools with parallel machining capabilities, including turning and milling operations. In this paper, we outline methods for (1) computing the machining axis for a part and (2) determining turning volumes for machining. Examples are included for both methods.

A computer-aided process planning methodology

This paper presents a computer-aided process planning (CAPP) methodology/prototype system. It is developed for those companies where engineers design and fabricate parts at different locations. The CAPP system begins with examining a workpiece's surface, and identifies all possible machining processes for all facets, one at a time. At this stage of planning, the methods used to identify machining processes are independent of any specific production facilities. In the next step, workpiece surfaces and machining processes are then examined together and any infeasible processes are taken out of the pool of machining solutions. Feasible machining processes may then be sent over to any production site. Optimal machining plans are identified based on local production conditions, e.g., machine capabilities, delivery schedules, personnel, etc. Because the CAPP system examines one surface at a time while generating the initial possible machining processes, any design changes to the workpiece surfaces would only affect changed surfaces and related processes. The majority of the machining processes remain unchanged. It is found that the CAPP system is particularly useful in a concurrent engineering environment, where a large number of design changes are made in early design stages.

SMT-TAB: A process planning system for PCB assembly using TAB and SMT

Process planning is a critical function in any manufacturing domain. This is especially true in the electronics manufacturing area where substantial heuristic and experiential knowledge is commonly used during process plan development. While research in computer-aided process planning (CAPP) has tended to concentrate in the machining realm, few CAPP systems have been developed for electronics manufacturing applications and more specifically for the printed circuit board (PCB) assembly domain. Besides, the CAPP systems that have been developed for this area have dealt with either insertion mount or surface mount PCB assembly processes only.

Development of a CAD-based intelligent manufacturing system

Abstract This research proposes a CAD-based manufacturing system that embraces computer-aided design, design for manufacturing and assembly (DFMA), computer-aided process planning (CAPP), computer-aided assembly planning (CAAP), and vision-robot integration. The proposed system starts with the design of products using a commercial CAD software, Autocad. The design data is then extracted from the CAD database and organized into a standardized product model. Interface programs are used to translate the geometrical and topological information in the model into DFMA, CAPP, CAAP and vision image representations. Based on the results generated by the interface programs the applications using artificial intelligence techniques can automatically generate redesign advises, CNC part programs, assembly sequence and instructions for robots.

An integration of feature recognition and process planning functions for turning operation

Abstract This paper deals with the development of a Computer Aided Process Planning(CAPP) system interfaced with CAD for turning operation. The developed system performs CAD interfaced feature recognition from part geometry database, and the decision procedures for process planning functions such as process and operation selection, machine tool selection, setup planning and operation planning. The system runs under personal computer environments and AutoCAD is employed as CAD system and Turbo-C is used for the decision procedures. A case study is performed to evaluate the performance of the system.

Face oriented neighbouring graph (FONG): a part representing scheme for process planning

Computer Aided Process Planning (CAPP) is the critical bridge between design and manufacturing. An expert process planning system named EPPSU has been developed to automate process planning and fixturing activities. The process planning system employs forward planning, i.e. it begins with the blank part and applies operations for each face/feature until it reaches the finished part model. After each operation the machined region is removed and a new intermediate model is generated. A part model description scheme called FONG has been utilized to represent blank, finished and intermediate models within the database. This paper describes the part representation scheme developed.

DESIGN, DEVELOPMENT AND IMPLEMENTATION OF AN INTEGRATED GROUP TECHNOLOGY AND COMPUTER AIDED PROCESS PLANNING SYSTEM

Abstract This paper discusses a Group Technology (GT) and Computer Aided Process Planning (CAPP) installation at JLG Industries, Inc., an international manufacturer and marketer of specialized hydraulic machinery. An efficient architecture for the design, development and implementation of the system is presented along with system design requirements and characteristics. A GT software shell is described, and for the architecture that is defined, a formal model of the process planning system is developed. The model is used as the basis for the creation of a generic semi-generative CAPP system. Implementation of the model along with experience with the system is included. Run time examples of the system are provided to illustrate the features of the system.

Knowledge Engineering Approach to Integrated Group Technology and Process Planning System for SME

With the emergence of CIM as a predominant thrust in discrete parts industries, computer aided process planning(CAPP) emerges as a key factor in CAD/CAM integration. This paper outlines the methodology and framework for development of a knowledge based prototype integrated group technology(GT) and CAPP system for small manufacturing enterprise(SME). An extended clustering analysis method evaluates the GT classification and coding and is embedded into the knowledge base. The system uses feature recognition techniques for evaluating the geometrical shape of a component in terms of generic features that could be used for manufacturing and a process planning system identifies the manufacturing operations and resources that is suited to manufacture the component. The paper also outlines the reviews of various approaches to the integration of GT and CAPP as used in integrated manufacturing.

Integration of CAPP and PPC –

Introduces concepts for the integration of Computer‐Aided Process Planning (CAPP) and Production Planning and Control (PPC). Characterizes the current situation regarding integration by a one‐way communication from CAPP to PPC, since a revised link is not envisaged. Introduces a new approach to full integration by the extension of functions within both systems′ components as well as integration of both data and information technology.