Completely synchronous manufacturing for automotive assembly — some lessons learned

The concepts of synchronous manufacturing look deceptively simple on paper. It appears obvious on the surface that when manufacturing operations are dependent upon one another, then the slowest operation will determine the pace of the combined operations.

Theory is one thing. Learning to really get a complex manufacturing and assembly system to work smoothly takes real patience.

One of the teaching tools was computer simulation with animation to demonstrate the concepts of synchronous manufacturing.

This paper focuses on 3 models developed using this simulation/animation tool.     

An object-oriented window scheme for representing design and manufacturing activities

The advanced manufacturing technology systems have brought new challenges to manufacturing firms all around the world. The increased need for higher productivity and zero detect products is forcing manufacturers to reevaluate their production philosophy, and improve their product design and manufacturing processes.

This paper presents an object-oriented, window-based scheme that represents various manufacturing activities such as planning, marketing, design, and manufacturing. In the presented scheme, each activity is considered an object and represented by a window.     

Automated inspection of circular parts

Automated vision inspection systems are the most versatile non-contact inspection systems. They are fast, compact, and remarkably accurate, thereby making 100% on-line inspection possible in modern manufacturing systems.

Roundness in one of the basic geometric elements in engineering design and manufacturing. As a result its inspection is an important part of the inspection of many industrial parts.

This paper discusses least-squares and minimax mathematical models and algorithms to determine the out-of-roundness error in automated roundness inspection. These errors are measured with respect to an ideal circle of specified radius.     

Using simulation to improve synchronous flow in pinion manufacturing

The quality of Management decision-making is greatly improved when a good animation of the manufacturing operation clearly shows how everything is going to work.

This paper describes the use of one of the best current animation tools, namely Witness 7 from AT&T ISTEL, applied to the decision to modify a current operation.

The paper describes how the simulation analysis played an important role in assuring that the management decision was correct.     

Comparison of two simulation/animation tools for synchronous manufacturing

This paper describes the use of two animation tools, namely CINEMA and PROOF, for simulation for the purpose of teaching synchronous manufacturing concepts.

This paper does not address the question of execution speed or comparison of results. The authors were really only concerned with the comparison of concurrent and post-processed animators.     

Manufacturing system application of a knowledge based simulation

The flexibility in a modern manufacturing facility introduces complexity to the decision making. The requirement for a real time control mechanism results in a need for an on-line simulation system that can simulate the complicated scheduling, routing and similar decisions required by the system.

This paper describes a knowledge-based simulation and control system written in PROLOG. This system is composed of four parts: a static data base, a dynamic database, a modeling knowledge part, and a simulation driver. The simulator contains the actual control mechanism of the physical system and can be removed from the system in order to simulate it.

The manufacturing system under investigation is a combination of flexible manufacturing cells that feed an automated assembly station. The knowledge-based simulation helps to develp and understand control mechanisms for that system, which can later be implemented in the physical system as the controller.     

Integration of simulation modeling and computer aided production management in computer integrated enterprise

Designing efficient and integrated manufacturing systems is the first step in attaining computer integrated enterprises (CIE). Integration of planning and implementation phases of manufacturing is essential for taking full advantage of the CIE. In order to design reliable and efficient manufacturing systems, the designers must consider the impacts of planning decisions made by computer aided production management (CAPM) modules on implementations held in manufacturing cells.

This paper focuses on two issues. The first issue is importance and necessity of integrating CAPM modules with manufacturing cells. The second issue includes major features of the object-oriented approach and their relevance to our objective of modeling a design framework which focuses on integration of CAPM modules and simulation models which emulate the manufacturing cells in the CIE environment.     

A decision support system for production planning and bid preparation for a small job shop manufacturer

With the advent of the inexpensive micro-computer, small manufacturers have been able to automate many applications in their day-to-day operations. Under the auspices of the State of Missouri “Productivity Improvement Program” - a program to aid small manufacturing businesses in improving their productivity, a Decision Support System (DSS) was developed to assist a small metals manufacturing company in production planning and bid preparation.

The DSS was developed at UMR by a graduate student as part of his master's thesis; the work was funded by both the Productivity Improvement Program and the small manufacturer. After development of the DSS, the graduate student was hired full time for one year to assist the manufacturer in implementing the DSS and to train on site personnel in its operation.

This paper discusses the development of the DSS, its implementation, and its utilization.     

A knowledge-based expert system for technology acquisition in small and medium scale manufacturing organizations

Consistent and reliable decision making for technology acquisition in small and medium scale manufacturing organizations is vitally important since these firms are the backbone of national economies, both in developed and developing countries. Because of their flexibility, small and medium scale firms are successful in adopting new technologies. However, a careful analysis should be conducted in technology acquisition decisions. Since these decisions require special type of knowledge and expertise, expert system, as an important tool of computerized decision making, can overcome these multidimensional difficulties.

This paper proposes a knowledge-based approach making use of issues such as sales, processes, costs and general policies, in decision processes for technology acquisition by small and medium scale manufacturing organizations in the developing environments.     

Equipment selection and justification through total productivity model

Traditional methods of economic analysis to justify equipment selection and use are based on several methods such as the Net Present Value, Break-Even Analysis, Pay-Back Period, Return on Investment, among others. However, with the introduction of automation, Flexible Manufacturing Systems (FMS), and Computer Integrated Manufacturing Systems (CIMS), such economic analyses have often resulted in decisions that management did not like to support but did not have much choice to avoid on account of pressure from manufacturing engineers, design engineers and others in the operations areas. The real problem of equipment selection and justification lies in the methodologies used.

This paper presents a unique approach to equipment justification by applying Sumanth's TOTAL PRODUCTIVITY MODEL, whereby the anticipated impact of the proposed equipment on profitability is assessed from the point of total productivity and the five partial productivities. Then, only if the equipment increases the total productivity level beyond its break even point, the equipment is selected or justified.

This method offers a non-traditional approach to justifying and selecting equipment in all types of environment. A numerical example is presented by using LOTUS 1-2-3^TM on an IBM PC. Advantages and limitations to this approach are discussed to provide a balanced perspective on the important issue of equipment selection and justification.     

Geometric reasoning for mill-turn machining process planning

An integrated system to support both product and manufacturing process design should be such that (1) the part design can be evaluated and redesigned based on manufacturability analysis and (2) the manufacturing processes can be selected efficiently and flexibly exploiting product information provided by part design representations.

In this paper, we describe the feature-based geometric reasoning system for part modeling and process planning as applied to mill-turn machined parts. The feature recognition system based on convex decomposition and the mapping method to relate the negative feature volumes to machining process classes are applied to mill-turn parts. Also, the geometry-based machining precedence relations have been generated for various alternative machining feature decompositions. The above geometric information is input to mill-turn machining process planning to determine machining process sequences and assignment to multiple spindles and turrets.     

How a leading heavy industries co., ltd in Korea implements JIT philosophy to its operations

In today's economic environment, Korean companies are confronted with fierce competition both domestic and offshore, in terms of quality and price. Industrialized countries like U.S.A., EC and Japan demand the Korean market be opened with high quality products, while developing countries like China, Thailand and Malaysia compete with Korea with low-quality, low-priced products.

This article is to decribe how a leading heavy industries co., ltd. in Korea has applied JIT philosophy to its operations to gain competitiveness in domestic and international markets, while improving manufacturing lead times, productivity, quality, setup reduction, space reduction, inventory reductions and purchase price reductions.     

Solution of scheduling problems of job-shop type FMS with alternative machine tools

FMS is now expected as one of the measures to cope with the recent requirements for the production. To elevate the performance of the FMS, it is necessary to establish its design methodology by which the flexibility and compatibility of the system functions can be determined. In this regard, one of the most important technical subjects is how to solve problems arising from machine breakdown to ensure optimum use of the system performance.

This paper deals with a scheduling problem of a job-shop type FMS with machine breakdown, taking into account alternative machine tools for each machining process of parts. The problem is solved by a discrete event simulation using SLAM II simulation language. Performance of the system is measured in terms of the machine utilization, mean flow time, total production, number of workpieces in-progress, and makespan.     

Synchronized manufacturing as in OPT: from practice to theory

Synchronized manufacturing as in the OPT system (Optimized Production Technology, by Creative Output Inc.) is a relatively new concept for production management.

This paper analyses the nine OPT rules, the OPT concepts and OPT philosophy in order to establish an analytical, theoretical basis for the OPT system. The analysis is based on systems theory concepts, mathematical programming theory and techniques, as well as queuing theory, the Pareto rule, and the Japanese production experience.

It is shown that the OPT rules reflect substantial integration of well established MS/OR techniques with the whole OPT philosophy. The paper analyzes the OPT classification of VAT plants and the Drum-Buffer-Rope concept used in OPT.

Our analysis makes a clear distinction between BIG OPT (the management system) and its subsystem SMALL OPT (the scheduler). The paper suggests that while the BIG OPT concepts may be applied in all types of processes, job shop processes and very complex assembly lines are the most suitable ones for the SMALL OPT scheduling system. The paper then shows the management by constraints methodology as a natural enhancement of the OPT concepts.     

A workbook-based methodology for implementing concurrent engineering

Concurrent Engineering demands a new way of working and many organisations experience difficulty during implementation. The research described in this paper has the aim to develop a paper-based workbook style methodology that companies can use to increase the benefits generated by Concurrent Engineering, while reducing implementation costs, risk and time.

The three-stage methodology provides guidance based on knowledge accumulated from implementation experience and best practitioners. It encourages companies to learn to manage their Concurrent Engineering implementation by taking actions which expose them to new and valuable experiences. This helps to continuously improve understanding of how to maximise the benefits from Concurrent Engineering.

The methodology is particularly designed to cater for organisational and contextual uniqueness, as Concurrent Engineering implementations will vary from company to company. Using key actions which improve the Concurrent Engineering implementation process, individual companies can develop their own ‘best practice’ for product development. The methodology ensures that key implementation issues, which are primarily human and organisational, are addressed using simple but proven techniques.

This paper describes the key issues that the majority of companies face when implementing Concurrent Engineering. The structure of the methodology is described to show how the issues are addressed and resolved. The key actions used to improve the Concurrent Engineering implementation process are explained and their inclusion in the implementation methodology described.

Relevance to industry

Implementation of Concurrent Engineering concepts in manufacturing industry has not been a straightforward process. This paper describes a workbook-style tool that manufacturing companies can use to accelerate and improve their Concurrent Engineering implementation.     

An automated method for the preparation of orthogonal arrays for use in Taguchi designed experiments

In the last several years, the use of designed experiments in manufacturing and engineering design environments has become increasingly popular through the introduction of the ideas of Dr. G. Taguchi. The Taguchi Method, a systematic technique for experimental design and analysis, employs team oriented solutions to analyze design and production problems and their causes. The Taguchi Method as provided a simplified approach to the design of statistically significant experiments. This has greatly increased the number of experimental design practitioners.

This paper presents a computer program that addresses the need for an automated system able to design the experimental matrices for the orthogonal arrays that are required by Taguchi's Method. The program was written tode sign simple arrays as well as complex multi-level arrays with two-way interactions.     

Cell production system for assembly

The recent diversification of market needs and shortened product life have necessitated frequent model changes which robot assembly lines can no longer accommodate.

This paper proposes automatic assembly by a cell production system as a possible solution to this problem. The system is a combination of intelligent assembly cells with a conveyor system or an automatic guided vehicle system. This not only requires very little start-up time but also has high dispersibility and expansibility, because each cell can function independently whereas a robot assembles several parts. A demonstration assembly cell proved to have high flexibility and capability for long unmanned operation.     

Computerizing productivity measurement for service installation companies

Due to the uniqueness of the service sector, attempts to directly apply manufacturing sector productivity measurement models to the service sector meet with difficulty. The major difficulty lies in the definition of output. However, with a step by step computer program, the determination of output along with productivity measurement for Service Installation Companies (SIC) can become a quick and simple process. The computer program prompts the user to input data for the base year along with the comparison year and computes the final productivity for each year. Productivity measurement can then be used as a valuable tool in the overall improvement of the utilization of inputs and outputs for Service Installation Companies.

This paper aims at providing a method of productivity measurement for SIC. This approach will guide the user of the program on how to obtain the necessary company data, and implement the program in order to obtain a final productivity measurement for SIC. The information and data used for this research are based on a productivity study conducted in an Air Conditioning & Heating Installation Company. The flexibility of the computer program allows for applications to many types of Service Installation Companies.

It is expected that this research will breach the gap that presently exists in the adaption of manufacturing sector models to service sectors, with computational enhancement provided through a computer software.     

A computerized integrated performance-reliability measure of a flexible automated production system

Flexible Automated Production Systems (FAPS) are designed as fault tolerant systems in order to ensure increased operating time.

This paper proposes an integrated performance-reliability model to evaluate different measures for a more complete and easy quantification of the fault tolerance characteristic of a FAPS and its ability to perform in degraded states.

Some examples are presented to show the applicability of computational algorithms.