Integration of process planning and scheduling in a job shop environment

Today’s manufacturing systems are striving for an integrated manufacturing environment. To achieve truly computer-integrated manufacturing systems (CIMS), the integration of process planning and production scheduling is essential. This paper proposes a framework for integration of process planning with production scheduling in a job shop environment for axisymmetric components. Based on the design specifications of incoming parts, feasible process plans are generated taking into account the real time shop floor status and availability of machine tools. The scheduling strategy prioritizes the machine tools based on cost considerations.     

A clustering-based modeling scheme of the manufacturing resources for process planning

Process planning determines how a product is to be manufactured and, therefore, is one of the key elements in the manufacturing process. The basic crux of computer-aided process planning (CAPP), however, is the diversity of manufacturing background and the complexity of process planning. Since the process plans are generated on demand with the manufacturing resources on a shop floor, modeling method of the manufacturing resources is one of most important issues in computer-aided process planning. Hence, the major objective of this research is to create a clustering-based modeling scheme of the manufacturing resources for process planning. This modeling scheme combines clustering method with averaging method so as to reasonably partition and classify the manufacturing resources on a shop floor. The proposed approach provides one of search strategies of machine tools for process planning, especially for the selection of machine tools. Finally, an illustrative example is applied to describe the clustering-based modeling scheme.     

动态CAPP系统及其加工资源决策方法的研究

为提高工艺计划的可执行性，提出一种动态CAPP系统集成模型。在工艺计划产生过程中，考虑车间加工资源的状态以及能力，实现加工资源的合理选择，产生具有良好生产指导能力的工艺计划信息。在资源决策过程中，基于BP神经网络进行车间加工资源决策，利用相关算法计算对应于每一加工特征的加工资源的优先指标，按照优先指标排序。结果表明，利用该方法产生的工艺计划符合车间资源能力，满足车间生产计划的需求。     

An integrated scheme for process planning and scheduling in FMS

Process planning and scheduling are the two important manufacturing functions involved in any shop floor activities. As functional integration is essential to realize the benefits of computer integrated manufacturing, a scheme for integration of process planning and scheduling has been introduced in this paper. The proposed scheme can be implemented in a company with existing process planning and scheduling departments when multiple process plans remain available on the shop floor. It consists of two main modules, introduced in detail in this paper. They are process plan selection module and scheduling module.     

基于实例推理的实时CAPP系统研究

现代生产不仅要求工艺设计系统能够快速响应产品的变化 ,而且要求所编制的工艺规程实用可行。本文开发了一种基于实例推理的实时CAPP系统 ,通过实例推理技术表示以往的工艺规程 ,同时考虑车间的加工能力 ,并将加工后零件的误差信息即时反馈回系统 ,从而快速、实时地生成符合生产要求的工艺规程。由于成功与失败的设计实例都被存入实例库中 ,系统实现了自学习功能 ,推理能力得到不断增强 ,最后通过回转类零件工艺设计实例验证了该系统的有效性     

Integrating Flexible Process Plans with Scheduling in Flexible Manufacturing Systems

This paper highlights the importance of integration between process planning and scheduling in flexible manufacturing systems (FMS). An effective integration increases the potential for enhanced system performance and enhanced decision making A framework that integrates flexible process plans with off-line (predictive) scheduling in FMS is presented. The flexibility in process planning, including process flexibility, sequence flexibility, and alternative machine tools, is discussed. The proposed framework consists of four integrated stages with the objective of reducing the completion time. The integrated stages include: 1. Machine tool selection. 2. Process plan selection. 3. Scheduling. 4. Re-scheduling modules. In addition, the paper proposes a new approach, namely the Dissimilarity Maximisation Method (DMM), for selecting the appropriate process plans for a part mix where parts have alternative process plans. The recursive structure of the framework provides a different approach, namely overlapping schedules, which considers a longer scheduling period as comprising several short scheduling periods. Knowing that neither the process plans nor the planned (predicted) schedules are truly followed on the shop floor, the related literature and the corresponding approaches are compared in order to envisage new approaches for closing the gap between process planning and scheduling.     

A Schema for Flexile Equipment Control in Manufacturing Systems

In this work a methodology is proposed for increasing the flexibility of the control software of Flexible Manufacturing Systems (FMSs). This greater flexibility is required due to factors such as uncertain product demand, uneven distribution of shop load, and machine or cutting tool unavailability. In the proposed framework the following modules were developed: (a) an automated process planning module which generates non-linear process plans for a given part, considering the shop floor resource availability; the non-linear plans include both material handling and material processing information; (b) a planning module that linearises the process plan aiming at minimising the total manufacturing time of the parts; (c) a NC program generation module, which generates the NC program for the chosen CNC machine(s). In order to increase the flexibility of the control software even more, a resource model was devised and implemented, which provides the necessary resource information for the above modules. Each of these modules is described within this paper, and details about the part and process plan representation necessary for this implementation are also given. A case study is presented in order to show the capability of the methodology.     

A blackboard-based process planning system for the surface mount manufacture of PCBs

This paper describes a real-time computer-aided process planning (CAPP) system for printed circuit board (PCB) assembly using surface mount technology. The prototype, dynamic, realtime CAPP system described uses a blackboard to integrate multiple knowledge sources (knowledge bases) in implementing the process planning procedure. The CAPP system is implemented using the expert system environment (ESE) and structured query language (SQL). The system uses two subsystems (knowledge bases). They are a planning subsystem which performs the static process planning task and a dynamic information processing subsystem which considers the real-time changes on the shop floor and routes the PCB assembly flow. The integrated system developed generates process plans that can be implemented in real time. The use of the blackboard concept for CAPP architecture is unique and well suited for this task.     

双语CAPP中机械制造工艺语言机器翻译研究

就具有工艺文件中英文自动翻译功能的双语CAPP及工艺翻译方法进行了研究。在分析机械加工工艺文件的语言特点和表示方法的基础上提出了基于语料库与语法规则相结合的工艺文件翻译方法,讨论了工艺语料库,机器词典,语言规则库的建立,提出了双语CAPP的结构框架。     

汽车覆盖件模具CAPP系统的开发研究

汽车覆盖件模具ＣＡＰＰ系统是单小批生产方式下的一种无编码的“广义ＣＡＰＰ”系统，现已用于微型轿车和轻型车的覆盖件模具工艺设计，并实现了工艺设计工作的全盘计算机作业化。该系统具有不同的工艺方案用于对不同的重要零件的工艺设计。     

A Branch and Bound Algorithm Based Process-Planning System for Plastic Injection Mould Bases

This paper describes the use of artificial intelligence in the process planning of plastic injection mould bases. The computer- aided process-planning system, developed for IMOLD? will extract and identify the operations required for machining. These operations are considered together with their precedence constraints and the available machines before the process plan for the mould base plate is generated. The process plan is optimised by a branch and bound based algorithm. Overall machining time has been proposed as the objective function for optimisation. The ability of this algorithm to search intelli-gently for a feasible optimised solution is illustrated by an industrial case study. A brief comparison with a genetic algor-ithm based process planning system is also made. The result of this development will allow users to optimise process plans easily for any given mould base, with options to suit dynamic changes on the manufacturing shop floor.     

A Generative Computer-Aided Process Planning System for Prismatic Components

This paper deals with design and development of a generative computer-aided process planning (CAPP) system for prismatic components and named PSG-CAPP. The proposed CAPP system has been divided into three modules. The first module is concerned with feature extraction. The second and third modules deal with planning the set-up, machine selection, cutting tool selection, cutting parameter selection, and generation of process plan sheet. The whole CAPP system is developed using Visual Basic 6.0 as front end and Oracle 7.3 as back end. The SolidWorks98 plus has been used for modelling, and feature extraction has been implemented using a program written in Visual Basic 6.0. The speciality of the developed CAPP system is that it is linked with the CAD module and it extracts the majority of features automatically prior to process planning. The developed CAPP system has been tested with aerospace components. The main feature of the proposed CAPP system is its ability to handle a variety of prismatic components and generate process plans for them. A case study has been included to highlight the potential of the CAPP system. ID="A1"Correspondance and offprint requests to: Professor P. V. Mohanram, Department of Mechanical Engineering, PSG College of Technology, Peelamedu, Coimbatore 641004, India. E-mail: msadaiah@yahoo.com     

面向全球制造的工艺设计与中英文翻译系统开发研究

全球制造策略要求工艺文件能用多种语言来表示以便于交流 ,而目前的 CAPP只能生成单一语言表示的工艺文件 ,因此 ,中英文工艺设计与翻译系统的开发是非常必要的。本文分析了 CAPP系统、机器翻译的研究应用现状和对工艺设计与中英文翻译系统需求 ,研究了工艺设计与中英文翻译系统的功能、总体结构与关键技术的实现方法 ,提出了用带有形式变量的工艺语句模板来实现工艺语句的规范化 ,以基于工艺语句模板的直译式翻译法为主、以基于语法规则的翻译法为辅的方法来实现的工艺文件翻译。在此基础上 ,结合航空制造业对外合作研制的需要 ,开发了一个航空工艺文件编制与中英文机器翻译系统 ,该系统己投入了实际应用     

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.Tape automated bonding (TAB), though a relatively new technology, is gaining importance in electronics assembly owing to its inherent advantages. The advent of fine pitch technology together with the ever increasing need for more inputs/outputs and greater pin counts in integrated circuit applications has enhanced the use of TAB technology in electronics manufacturing. This trend has been further augmented by the increasing need for compactness in consumer electronics.This research designed and developed a prototype CAPP system for the PCB assembly domain. The system developed generates a process plan for PCBs populated with surface mount and/or TAB components. An artificial-intelligence based expert system approach has been used in the design and development of the CAPP system. Outputs generated by the system are presented along with ideas for future research.     

Object-oriented and fuzzy-set-based approach for set-up planning

Set-up planning is not only a key element of computer-aided process planning (CAPP), but also a key factor for the integration of CAPP with computer-aided fixture planning (CAFP) and production planning and scheduling (PPS). In this work, an object-oriented and fuzzy-set-based approach is developed for set-up planning. Object-oriented technology is employed to represent set-up planning knowledge and generate alternative set-ups which can respond to the dynamic manufacturing resource and facilitate the CAPP/PPS integration. Based on fuzzy-set theory, a fuzzy evaluation function is proposed to produce optimal set-ups. Combined with a real project, a set-up planning system is developed to generate alternative and optimal set-up plans for the machining of prismatic parts.     

敏捷制造车间任务规划系统的设计与开发

敏捷制造车间任务规划作为联系敏捷制造车间计划与敏捷制造车间调度与控制的纽带，是计划任务在敏捷制造单元层上的动态分配。对敏捷制造车间任务规划系统进行了设计，构造了基于多Agent的体系结构，定义并描述了敏捷制造车间任务规划问题，并在分析敏捷制造车间各个智能体行为的基础上，提出了基于知识和联盟形成算法的敏捷制造车间任务规划方法。该方法。是敏捷制造车间任务规划系统的核心。介绍了开发的敏捷制造车间任务规划系统。     

基于网络制造环境的机床刀具动态选择模型的研究

计算机辅助机床和刀具选择(CATS)是计算机辅助工艺设计(CAPP)系统中的一个至关重要的环节。本文讨论了在基于网络的制造环境下机床和刀具的动态选择。它能帮助现有的CAPP系统进行具体的、经济的工艺规划,并且让设计者有效地进行产品的可制造性评估。特别是将选择机床与选择刀具相结合能对经济生产进行优化决策。     

Integration of Process Planning and Scheduling Using Simulation Based Genetic Algorithms

Process planning and scheduling are traditionally regarded as separate tasks performed sequentially; but, if the two tasks are performed concurrently, greater performance and higher productivity of a manufacturing system can be achieved. Although several workers have addressed the process plan selection problem in recent years, their main approaches are to select process plans from plan alternatives by taking into account the similarities among process plans of the parts. In this paper, we propose a new approach to the integration of process planning and scheduling using simulation based genetic algorithms. A simulation module computes performance measures based on process plan combinations instead of process plan alternatives and those measures are fed into a genetic algorithm in order to improve the solution quality until the scheduling objectives are satisfied. Computational experiments show that the proposed method reduces significantly scheduling objectives such as makespan and lateness.     

A Cascading Auction Protocol as a Framework for Integrating Process Planning and Heterarchical Shop Floor Control

A new contract net-style auction protocol is proposed as a framework for integrating process planning and shop floor control in heterarchical manufacturing systems. Process planning is partitioned into on-line and off-line activities; off-line process planning decisions are represented in a graph format and used as input for on-line process planning activities performed by machine controllers. Triggered by the opening round of an auction, the final on-line stages of process planning are dovetailed with the resource allocation process in the shop floor control system. The auction process allows final process planning decisions to be based on timely information, relying on the distribution of static process planning information rather than the distribution of a model of dynamic shop floor status and allowing a controller to identify all the primary and secondary resources and operations that must be provided for the incremental processing of a part.     

Parametric process planning based on feature parameters of parts

This paper presents a model parametric process plan that is dependent on feature parameters of parts, and proposes a solution for the automated process planning of part families. Based on the parametric process plan templates for part families and the feature parameters of new parts, a prototype system is developed. First, parts are grouped into families considering their geometric or manufacturing similarities, and the parametric process plan template is pre-created for each family. Then, to plan the process of a new part, the system extracts feature parameters from its feature-based model and generates an a parametric process plan by searching the template library and solving related constraints. Finally, the system outputs the process plan sheets, if necessary. Although the system cannot creatively generate process plans for brand new parts, the system can meet two important requirements of the real industrial world to CAPP systems, that is good system performance and rapid response.