Databases for Production Management

339 Pages·1990·31.367 MB·English

by  R. Companys, P. Falster and J.L. Burbidge (Eds.)

DATABASE S FOR
PRODUCTIO N
MANAGEMENT
Proceeding s of the IFIP TC5/WG 5.7 Working Conferenc e on
Design, Implementatio n and Operation s of
Database s for Productio n Managemen t
Barcelona , Spain, 10-12 May, 1989
Edited by
RAMON COMPANYS
E.T.S.E1B.
Universitat Politecnica de Catalunya
Barcelona, Spain
PETER FALSTER
Electric Power Engineering Department
Technical University of Denmark
Lyngby, Denmark
JOHN L BURBIDGE
Wild Goose Leys
Abbots Ripton
Huntingdon, Cambridgeshire, UK.
1990
NORTH-HOLLAND
AMSTERDAM · NEW YORK · OXFORD · TOKYO
ELSEVIER SCIENCE PUBLISHERS BV.
Sara Burgerhartstraa t 25
RO. Box 211,1000 AE Amsterdam , The Netherland s
Distributors for the United States and Canada :
ELSEVIER SCIENCE PUBLISHING COMPANY INC.
655 Avenue of the Americas
New York, N.Y 10010, U.S.A.
Librar y of Congres s CatalogIng-ln-Publ1catIo n Dat a
IFIP TC5/WG5.7 Working Conferenc e on Design , Implementation , and
Operation s of Database s for Productio n Managemen t (1989 : Barcelona ,
Spa i ç)
Database s for productio n managemen t proce:eding s of the IFIP
TC5/WG5.7 Working Conferenc e on Design , Implementation , and
Operation s of Database s for Productio n Management , Barce1ona,.Sp a é ç,
10-12 May, 1989 / edite d by Ramon Companys . Pete r Falster , John L.
Burb idge .
ñ. cm.
Include s bibliographica l references .
ISBN 0-444-88658- 3 (U.S.)
1. Productio n management—Dat a bases—Congresses . I. Companys ,
Ramon . II. Falster , P. III. Burbidge , John L. IV. IFIP
TC5/WG5.7. V. Title.
TS155.A1I41 2 1989
658.5'0028 " 5574~ac2 0 89-7834 8
CIP
ISBN: 0 444 88658 3
© IFIP, 1990
All rights reserved . No part of this publication may be reproduced , stored in a retrieval system or transmitted in
any form or by any means , electronic, mechanical , photocopying , recording or otherwise, without the prior written
permission of the publisher, Elsevier Science Publishers B.V./Physical Science s and Engineering Division,
P.O. Box 103,1000 AC Amsterdam , The Netherlands .
Special regulations for readers in the U.S.A. - This publication has been registere d with the Copyright Clearance
Center Inc. (CCC), Salem, Massachusetts . Information can be obtained from the CCC about conditions under which
photocopies of parts of this publication may be made in the U.S.A. All other copyright questions , including photo-
copying outside of the U.S.A., should be referred to the publisher, Elsevier Science Publishers B.V., unless otherwise
specified.
No responsibility is assume d by the publisher or by IFIP for any injury and/or damage to persons or property as a
matter of products liability, negligence or otherwise, or from any use or operation of any methods , products,
instructions or ideas contained in the material herein.
Pp. 91-108: copyright not transferred .
Printed in The Netherlands .
í
FOREWOR D
At most of the conferences I attend, I read two or three papers of special interest, and only
skim through the rest. If however, one undertakes, as I have done, to edit the proceedings,
one has to read every word of every paper. There have been conferences where this would
have been painful, but in the present case I have found it rewarding. I believe that this book
will be essential reading in the future, for anyone concerned with the design of data bases
for Production.
IFIP WG 5.7 is a working group concerned with the computerisation of Production Man-
agement. It draws it's membership from 25 different countries and holds it's meetings in a
different member country each time. The proceedings of it's meetings are published, and
the resulting books provide a comprehensive library of knowledge in the field of Production
Management systems.
Most of the IFIP WG 5.7 working conferences cover a wide range of subjects inside the
production field, and this is reasonable in an organisation where the participants have a wide
range of interests. In the present case however, we were lucky to find in the design of data
bases, a specialist subject which is of major importance at the present time to all those
working on the computerisation of production management. It was also one of interest to all
members of the working group.
This present volume of proceedings is unusual in one other respect. It has three editors, -
one Spanish, one Danish, and one English. The first is Professor R. Companys of the
Polytechnic University of Catalonia, in Barcelona. He organised and managed the conference
in his university, and is the principal Editor of this volume. The success of the conference
was mainly due to his efforts, and I would like to add my congratulations to the many he
has already received. The second Editor is Dr. Peter Falster of the Technical University of
Denmark. He is the retiring Chairman of WG 5.7 and is largely responsible for the success
of the working group in recent years. He has co-ordinated the preparation of the conference
papers for publication. Finally, I am the third Editor. I was responsible for checking the
English used in the papers, and also for writing the review.
Finally we acknowledge with thanks the help given by Ms Inge Christiansen of the Technical
University of Denmark who typed part of the manuscripts, redraw many of the illustrations
and arranged the papers for publication.
John L. Burbidge
September, 1989
OPENING REMARKS
10 Years with IFIP WG 5.7 in CAPM
by
Peter Falster
Chairma n
On behalf of IFIP Working Group 5.7 on Computer Aided Production Management it is a
pleasure for me to welcome all participants to this working conference on Design, Imple-
mentation and Operation of Databases for Production Management.
This conference takes place 10 years after the start of this working group.
Working Group 5.7 was started by Professor Asbjorn Rolstadas, who was its chairman for
the first five years. It had its first meeting in Copenhagen on August 31th, 1979. Since that
date the group has grown from 15 members from 9 countries to 49 members from more than
24 countries all over the world. We have held a working group meeting every year, arranged
7 working conferences and 3 open conferences (APMS) with subsequent publication of the
proceedings. This year sees the 10th anniversary of WG 5.7.
If we look back over the 10 years we see several important milestones in the work of WG
5.7. The following conferences have been held:
Production Management Systems, Trondheim (1980)
Advances in Production Management Systems, Bordeaux (1982)
PMS - Strategies and Tools for Design, Vienna (1983)
Modelling Production Management Systems, Copenhagen (1984)
Decentralized Production Management Systems, Munich (1985)
Advances in Production Management Systems, Budapest (1985)
New Technologies for Production Management Systems (1986)
Modern Production Management Systems, Tokyo (1987)
Information Flow in Automated Manufacturing Systems, Washington (1987)
Knowledge Based Production Management Systems, Galway (1988)
In addition we have published the IFIP Glossary of Terms used in Production Control by
Professor J.L. Burbidge, based on input from the working group members, and Professor A.
Rolstadas has edited the IFIP State-of-the-art book: Computer Aided Production Management.
Spin off from over group work cab be seen in the international cooperation in Esprit projects,
between individual working group members, visiting and exchanging ideas and papers.
You can see from the books published that we have covered a very broad field:
System Design and Implementation Techniques
Databases
Simulation and Modelling
Management Functions
Knowledge Engineering
Decentralization
Production Control Techniques and Methods
Production Philosophies
Terminology
viii
Members with various background from university and industry have contributed to this
work extensively in an interdisciplinary way.
IFIP- International Federation for Information Processing - is a truly international organization
as can be seen from the membership of this working group. IFIP is oiganized in technical
committees. Technical committee 5 on Computer Applications in Technology is the
administrative unit of several working groups, one on CAD, one on CAM, one on Computerized
Process Control, one on Maritime industries, one on Computer Aided Production Management,
Product Specifications, and Product Documentation, one on Computers in Food Production
and Agriculture and one on Computer Graphics.
The present conference here in Barcelona deals with all aspects of the "Design , Implementatio n
and Operation of Databases for Production Management Systems". This working conference
has been organized by Professor Companys, from Escola Techica Superior d'Enginyers
Industrials, who have also given their facilities to host the conference. From my own
experiences I know it is a major task to organize such a working conference and I would
like to take the opportunity to thank the organizer professor Companys and his colleagues
for all the effort they have put into this conference to make it a success. Papers have been
reviewed and selected by an international program committee consisting of members of IFIP
WG 5.7. We are most indebted to the authors of these papers, whose contribution will ensure
the success of the conference. All papers will be published by North-Holland after editing.
Dr. Augustin resigns as secretary and I resign as chairman of this working group after serving
for 5 years. The new chairman will be professor G. Doumeingts, University of Bordeaux;
the new vice-chairman, professor J.C. Wortmann, from the University of Eindhoven, and
the secretary, Dr. Eero Eloranta from Technical University of Helsinki. I would like to thank
Dr. Augustin the secretary, the vice-chairman Professor Doumeingts, and all working group
members for their strong support during the five years of my chairmanship.
Finally, I hope this conference will be held in an atmosphere of friendship and team-work
between participants. I wish you some interesting days in Barcelona.
ix
INTERNATIONAL PROGRA M COMMITTEE
Companys, R. - Spain (Chairman) Mazumder, R.B. - Switzerland
Augustin, S. - FRG McLean, C.R. - USA
Beier, H.-H. - FRG Mertins, K. - FRG
Browne, J. - Ireland Okino, N. - Japan
Burbidge, J.L. - Great Britain Pappas, LA. - Greece
Doumeingts, G. - France Persson, G. - Norway
Eilon, S. - Great Britain Radosinski, E.T. - Poland
Eloranta, E. - Finland Renchu, G. - P.R. China
Escudero, L.F. - USA Riis, J.O. - Denmark
Falster, P. - Denmark Rolstadas, A. - Norway
Favrel, J. - France Schoemaker, J. - Belgium
Fuyuki, M. - Japan Stecke, K.E. - USA
Gundling, M.R. - Japan Stienen, H. - Switzerland
Halevi, G. - Israel Szelke, E. - Hungary
Hirsch, B.E. - FRG Takeda, K. - Japan
Hofer, H.C. - Lichtenstein Uronen, P. - Finland
Hubner, H. - FRG Villa, A. - Italy
Hutchinson, G.K. - USA Vlietstra, J. - The Netherlands
Inoue, I. - Japan Walter, C. - Brasil
Jagdev, H. - Great Britain Wildemann, H. - FRG
Kerr, R.M. - Austria Wortmann, J.C. - The Netherlands
Kusiak, A. - USA Yang, G.X. - P.R. China
Lund, K. - Sweden Yoshikawa, H. - Japan
Lundell, P. - Sweden Zelenovic, D. - Yugoslavia
Databases for Production Management
R. Companys, P. Falster, and j!L Burbidge (Editors)
Elsevier Science Publishers B.V. (North-Holland) 3
© MP, 1990
A CONCEPTUA L MODEL FOR PRODUCT-TYPE S
AND BILLS-OF-MATERIAL :
APPLICATIO N OF A SET-THEORETI C APPROAC H
E.O. de Brock, F. Remmen and J.C. Wortmann
Keywords: bills-of-material, configuration management,
conceptual data models, data modelling languages,
product modelling.
Abstract
A central part of information systems in manufacturing organizations deals with prod-
ucts and product structures. Products to be manufactured and their composition are
usually maintained in bills-of-material (BOM) systems. Many organizational functions
make use of BOM systems in manufacturing firms. A well-known problem is, that each
of these functions has diiferent requirements regarding the definition of one or more
product-types and the associated attributes. As a result, many firms face problems
with respect to consistency, security, and the nature of the conceptual data model for
this part of their information system.
The present paper shows a method for solving these problems by improved conceptual
data modelling. The data modelling approach used here is based on set-theory. It
formalizes subtypes and constraints to be maintained by a DBMS. The mathematical
foundation of the approach is treated elsewhere more thoroughly.
In the paper, the method is applied to the modelling of product-types and bills-of-
material. The result is not only a conceptual model. More important is the fact that
the approach presents a precise and formal method for a user organization to obtain
proper understanding of its own problem area. By defining constraints in the conceptual
data model, the approach also enables the user organization to balance the trade-off
between flexibility and costs in the development of application software.
4
1. INTRODUCTION
In manufacturing organizations, a central part of many information systems consists
of the data on product-structures and product-types. These product-types include
the end-products sold to customers, the components and materials purchased from
suppliers, intermediate products in manufacturing processes, families of products (con-
ceptually) grouped together for certain decision support systems, and so on. Moreover,
the data on product-structures describe the relationships between products. These re-
lationships are often of the "goes-into" type; in that case they are usually modelled
and stored in the Bill of Material (BOM) system, that is well known in nearly every
manufacturing company.
Traditionally, all product-types are considered to belong to a super-type, that will be
referred to as items, and all "goes-into" relationships are considered to belong to one
relationship type, to be called BOM.
Closer examination of the information requirements of different user categories reveals
some problems. All these problems have the following fact in common:
for different subsets of items, different sets of attributes have to be defined.
For example, purchased items have an external supplier, while for non-purchased items
supplier-data are non-existent. For non-commercial items the sales-data are not defined.
Many other examples can be given, as will be shown. We will first explain why this
fact constitutes a problem.
At a first glance, the question of non-existence of attributes for subsets of items can be
dealt with by the introduction of null-values. Such a null-value can be used to indicate
the irrelevancy of an attribute for a subset of items (for instance a null-value can be
used for the supplier attribute of a non-purchased item). However, consistency of the
database would require that this null-value be specified for all items for which the
attributes are non-existent, and that it is not specified for all other items. If we would
like to check this requirement, additional attributes are required, indicating whether
an item is a purchased item, respectively a commercial item, and so on. This solution
can be found in many BOM systems that are currently being used in practice. In fact,
such a solution defines subtypes, but not at the infological (or conceptual) level. This
solution and similar ones have the following disadvantages:
1. At the infological level of design, it hides the fact that users actually think in
terms of these "subtypes".
2. In developing application software, it is often quite important to know the set-
relationships between subtypes, e.g., whether certain subtypes are mutually ex-
clusive, or whether one subtype is a subset of another subtype; this knowledge can
simplify application development considerably! Due to point 1, this knowledge is
not specified formally in the infological design phase, but employed informally in
software development.
3. Because set-relationships between subtypes are not specified formally, they cannot
be validated by screening procedures. At best, the application software performs
a check on its own assumption. Even then, a change in the values of attributes
may create a software error.
5
4. Because set-relationships between subtypes have not been specified formally, the
infological design overlooks a natural means for decomposition of information sys-
tems into loosely coupled parts. When subtypes are specified conceptually, it is
quite obvious to see for instance that an end-item of an assembly plant cannot
be considered as a purchased item by the same plant. So when these two sub-
types are distinguished, no other relationships exist between these subtypes than
"goes-into" relationships. Much effort currently put into "distributed processing"
consists of solving problems at the datalogical level (Pels and Wortmann [6]).
5. The construction with null-values complicates query handling and answering.
For these reasons, conceptual data-modelling techniques allowing a formal definition
of set-relationships between subtypes are crucially important for the description of
products in manufacturing organizations. Such techniques are developed in De Brock
[2]. In this paper, we will employ these techniques specifically for the description of
item-subtypes.
The problem is stated more formally in an artificial case in Section 2; the case is based
on many industrial experiences. Section 3 gives a solution to the problem of Section 2
on the object modelling level. Section 4 presents a solution on the data modelling level.
Section 5 concludes and summarizes the paper. In the appendix, formal definitions are
given of the mathematical concepts used in this paper.
6
2. THE PROBLEM
2.1. Case description
Consider a production division such as depicted in Fig. 1. The actual manufacturing
takes place within a number of production units (cf. Bertrand and Wijngaard [1]) or
departments.
The production control problem can be decomposed into a control problem within these
departments ("departmental control") and a control problem to coordinate the flow of
products between the departments ("logistics control"). Furthermore, we also consider
a commercial division that configurates products for clients, forecasts the demand, and
performs commercial activities. Within the scope of this paper, we will exclude other
parties which may be important in reality, such as Product Engineering, Service, and
Accounting.