Distributed Design Of Product Oriented Manufacturing Systems

Abstract

Manufacturing leanness and agility are requirements of today’s manufacturing systems. Leanness call for a best fit of the
manufacturing systems to products, therefore requiring product oriented manufacturing systems (POMS). Manufacturing agility
can be achieved through easy systems reconfiguration to fit changing manufacturing requirements, which may mean dynamically
configuring POMS. For this a suitable design system is required. Due to complexity of this design, and to the need for using
suitable design methods, which may not be available locally, distributed sources of design services can be used. This paper
presents and describes a prototype of a Distributed Design system for POMS based on a POMS design methodology and distributed
suppliers of design services.

Full text

Page 1

Distributed Design of Product Oriented
Manufacturing Systems



Sílvio do Carmo-Silvaa, A.C. Alvesa C., P. Novaisb, M. Costac,, C. Carvalhob,
J. Costab, M. Marquesb
aCentre for Production Systems Engineering (CESP), University of Minho, Campus de
Gualtar, 4700-057 Braga, Portugal (scarmo@dps.uminho.pt; anabela@dps.uminho.pt)
bDepartamento de Informática-CCTC, University of Minho, Campus de Gualtar, 4700-057
Braga, Portugal
(a35288@alunos.uminho.pt; jorgemaiocosta@hotmail.com; marquesmps@gmail.com;
pjon@di.uminho.pt)
c(costamiguel@bragatel.pt)





Manufacturing leanness and agility are requirements of today’s manufacturing
systems. Leanness call for a best fit of the manufacturing systems to products,
therefore requiring product oriented manufacturing systems (POMS).
Manufacturing agility can be achieved through easy systems reconfiguration to
fit changing manufacturing requirements, which may mean dynamically
configuring POMS. For this a suitable design system is required. Due to
complexity of this design, and to the need for using suitable design methods,
which may not be available locally, distributed sources of design services can
be used. This paper presents and describes a prototype of a Distributed Design
system for POMS based on a POMS design methodology and distributed
suppliers of design services.




1. INTRODUCTION

Industrial companies, nowadays, live in a paradigm of high competition in a market
environment of frequently changing product demands. Therefore, manufacturing
leanness and agility are requirements of today’s manufacturing systems as a means
of effectively answer varying market requirements and maintain competitiveness.
Leanness call for a best fit of the manufacturing systems to manufacturing
requirements of products. Manufacturing agility can be dealt with by frequently
adjusting or reconfiguring manufacturing systems to fit changing manufacturing
requirements. Thus apparently, both leanness and agility can be achieved through
Product Oriented Manufacturing Systems (POMS). These may be defined as
systems interconnecting manufacturing workstations or cells, usually involving
people, which simultaneously and in a coordinated manner address the manufacture

Page 2

2 BOOK TITLE

of a single product or a family of similar products, subject to frequent
reconfiguration to be adapted to changing manufacturing requirements of products
or product families (Carmo-Silva et al., 2005).
The design of POMS tends to rely mostly on human expertise and ability for
arriving to acceptable system configuration solutions to fit continuously changing
product demand. This design approach is slow and ineffective and tends to introduce
inefficiency on manufacturing operations activity. Such human based design may be
justified when no suitable design system for POMS design, is available. Since, in
addition to several methodologies (Suh, 1990, Burbidge, 1989, Black, 1991,
Cochran et al., 2002), there are available a large variety of methods and procedures
to aid the manufacturing system design function (Suresh and Kay, 1998, Irani, 1999)
apparently there is no reason to base POMS design almost exclusively on human
expertise. The use of design systems based on computer applications, which
implement valid methods under a suitable design methodology, can provide the
missing tool required for achieving fast and good reconfiguration solutions of
POMS, to fit changing manufacturing requirements. However, not always the
methods required are locally available. Due to this, many design functions may have
to rely on distributed sources of design services. This paper presents and describes a
prototype of a distributed design system for POMS based on a manufacturing system
design methodology and distributed suppliers of design services.
The paper presents in section 2 a description of the computer aided design
system framework organized around a POMS design methodology. In section 2 the
architecture components and prototype of a POMS design system based on a
community of servers providing design services is described. In section 4 a
conclusion is presented.

2. COMPUTER AIDED DESIGN SYSTEM FRAMEWORK
FOR POMS DESIGN

2.1 CADS_POMS framework

POMS design can be based on a design methodology. One such methodology,
named GCD - Generic-Conceptual-Detailed - was proposed by Silva and Alves
(2002). It essentially puts forward a hierarchical multilevel and iterative design
process for POMS. Important data and restrictions are considered and a range of
methods can be used in the POMS design process. Under this methodology the
design process is organized in three main phases and includes several design stages
and activities.
However important the GCD methodology may be, it can be of little use if not
supported by a computer aided design system (CADS). This must address POMS
design activities from strategic planning to the POMS organization and production
control mechanisms definition. A CADS_POMS framework based on the GCD
methodology for POMS design is shown in Figure 1.

Page 3

Distributed Design of Product Oriented Manufacturing Systems
3


Generic design (A1)
Detailed design (A3)
Product families for cells formation
(A31)
Conceptual design (A2)
Product families
Selected conceptual cells
Identified conceptual
workstations
…
Workstations selection (A22)
Intercellular organization and
coordination (A35)
POMS: families, resources,
cells, operation modes,
intra and intercellular
layout, planning, control
and system coordination
…
Conceptual cell configurations
selection (A21)
Conceptual cells
Conceptual Workstations
Process plans
Product operations
...
Results
Manufacturing approach to
demand
Aggregated families and quantities
Selected resources
Selected configuration of
manufacturing system
…
Objectives
Technology
Demand forecast
Resources
Shop floor data
…
Input data
Results
Production orders
Operational cells
Layout types
Planning and control
systems
…
Input data
Algorithms
Heuristics
Methods database
Production Planning (A11)
Input data
Generic configuration of
manufacturing system
selection (A13)
Analysis of company and
market manufacturing
resources (A12)
Results
Intracellular organization (A34)
Instantiation of workstations (A33)
Conceptual cells instantiation (A32)

Figure 1. A CADS_POMS design framework based on the GCD methodology

3. A DISTRIBUTED DESIGN SYSTEM

3.1 System Architecture and functionalities

Figure 2 illustrates the main components and gives a simplified view of the
architecture of the POMS distributed design system that may be seen as an
instantiation structure of the CADS_POMS design framework presented in figure 1.
The system is organized around a central POMS database, a POMS design
methods database, a distributed set of design methods servers, for aiding POMS
design, and a interactive human-computer POMS design application module, with
graphical user interfaces, named POMS designer.
Although some design methods and procedures for POMS design may be
available locally, many more can be available through several servers distributed
globally. These are identified as POMS design methods servers. These servers
supply POMS design services requested by the POMS designer to perform design

Page 4

4 BOOK TITLE

functions or tasks under the CADS-POMS design framework show in figure 1.

POMS
Database

Products,
Resources,
Operations
Processes
..
POMS
design
methods
database
POMS
Designer
POMS design
methods server

Globally distributed servers
...
POMS design
methods server

POMS design
methods server

...


Figure 2 - POMS design system components and architecture
The POMS designer interacts with all components of the POMS design system.
It interacts with the POMS system Database in many ways. Initially products,
manufacturing resources and a set of generic operations, which can be instantiated
by process planning for defining the process plan for each product to be
manufactured, are specified or copied into the database. Then, the user can plan the
process for manufacturing each product by using the set of standard generic
operations which are then parameterized according product processing requirements
(Carmo-Silva et al., 2005). Resources, mostly machines that are central to
workstations, capable of carrying out product operations, are then chosen according
to resource attributes and processing capabilities. Estimates of operation processing
times for each resource are also produced. This process is totally under control of
user, although some process planning systems may be used to easy this task. These
described functions are essential for generating the main data and information
required for POMS design. A computer application addressing this process of data
generation for POMS design has been already developed (Carmo-Silva et al., 2005).
This can be seen as an important part of the prototype of the POMS design system
here reported.
Since it is sought frequent system configuration for adapting production systems
to changes in product demand, we may refer to this POMS design as POMS
reconfiguration.

3.2 Distributed Design Services

POMS reconfiguration relies not only on methods locally available but also on
design methods implemented and run at distributed servers. The interaction of
POMS designer with the methods database is the first step in the POMS
reconfiguration process. This database provides information about the location of
servers and the list of methods that are available, and where, for solving specific
design tasks or problems, at request of the POMS designer. The methods database

Page 5

Distributed Design of Product Oriented Manufacturing Systems
5

also provides information about the data input formats which are used for each
method.
The following assumptions were considered in the modeling of the methods
database: each method solves a specific problem or design task; each problem
relates to a particular design activity in a design phase of the GCD methodology
summary illustrated in figure 1; one particular design method may have
implementations in more than one server.
The input data for running a method is prepared by the POMS designer and sent
to a suitable methods server, which then run the method and send back results to
POMS designer in an already known format. The communication process is carried
out over the network through the TCP/IP protocols.

3.3 Running Methods on Servers

In an implementation example of the distributed POMS reconfiguration process a
methods server application was developed. This, once operating in a methods server
that is active, allows the server to accept requests from POMS designer for design
tasks. Figure 3 identifies the graphical interface of the methods server application.


Figure 3 - Methods server application interface: a) waiting for the a request from a
client; b) input data from the request and output data sent to the client
a) b)

It shows the server capability to offer two methods for POMS design tasks,
namely the DCA – Direct Clustering Algorithm (Chan and Milner, 1982) and the
SLC - Single Linkage Clustering (McAuley, 1972) methods. These are useful for
forming manufacturing cells by identifying product families, based on process plan
similarities of products. This is part of activity A31 of the detailed design phase A3
(Carmo-Silva and Alves, 2006), as shown in figure 1. Input data sent by the SPOP
designer, prepared with basis on a SQL stored procedure for the DCA
implementation on the server, is illustrated in the figure 3.
Once there is a need for a design task to be carried out the SPOP designer must
choose a suitable method from a methods list provided in the methods database and,

Page 6

6 BOOK TITLE

additionally, select the server do supply the service.
A request is then generated and stored in a list of requests, figure 4. This list of
design service requests by the SPOP designer is generated as a matter of monitoring
the answers of servers, and allowing request repetition when for some reason,
related for example with communications or server operation, no answer is received
from servers.



Figure 4 - Requests list
A summary of the request and service supply process is show in figure 5. The
need for a design task to be performed in a particular activity of design phase leeds
to the choice of a design method listed in the methods database and a selection of the
suitable server. This permits a request for the design task after due preparation of the
method input data in the correct format. The answer from the server to the SPOP
designer request is provided through the methods server application for a of request
output, figure 5.

3.4 Managing Distributed Servers Community

The system architecture allows dynamic updating of the community of servers
providing design services. Any server that joins the community must be registered.
This means supplying its location and specifying the design services that it offers.
This is done through the SPOP designer that, in addition to ensuring the POMS
design process has also the task of updating the method database. This means adding
the new server to the methods’ servers list, in the methods database, and specifying
the design phase and problem that each new method solves. Moreover, the input
data format required by each method, offered by the new server, is also specified. In
the actual implementation this is done through SQL stored procedures. The
removing of methods and servers from the methods data base can also be carried

Page 7

Distributed Design of Product Oriented Manufacturing Systems
7

out.







“A31” menu
Matriz 0/1
generation
Request - input
Request- output
Methods server application (fig. 3)
Selection of
method and
server
Request
generation

Figure 5 - Forms and menus for the design service request and design results
provided


4. CONCLUSION

Frequent reconfiguration for adapting POMS to changing product manufacturing
requirements is one way of achieving both manufacturing agility and leanness for
gaining competitive advantage in the unpredictable product demand environment of
today and tomorrow.
Although in simple manufacturing situations human expertise and ability may be
enough to arrive to good POMS reconfiguration solutions, better results are likely to
be obtained with a suitable computer aided design systems for POMS. This must be
structured around a design framework or methodology which can explore the use of
several methods, in different design phases, which have been developed over the
years, by many authors, and that can of great value in the POMS reconfiguration
process.
The idea of developing an autonomous monolithic POMS design system seems
to be unfeasible and not recommended, for many reasons including the difficult of

Page 8

8 BOOK TITLE

making locally available the necessary POMS design methods which, nevertheless
can be accessed through the Internet. Moreover the dynamic up-dating of the system
“intelligence” for POMS design, would be a difficult task. Better would be to
provide the POMS design system with access to a large community of POMS design
service providers. This idea has been explored to develop a computer aided design
system, based on a CADS-POMS framework structured under a POMS design
methodology and a community of distributed servers providing POMS design
services through the Internet. A simple prototype of such a system is described in
this paper.

6. REFERENCES

1. Black JT. The Design of the Factory with a Future”, McGraw-Hill, 1991.
2. Burbidge JL. Production Flow Analysis for planning Group Technology. Clarendon Press, Oxford,
1989.
3. Carmo-Silva S, Alves AC, Costa M. A Computer Aided Design System for Product Oriented
Manufacturing Systems Reconfiguration. Intelligent Production Machines and Systems
(Proceedings of the 1st I*PROMS Virtual International Conference), D. T. Pham, E. E. Eldukhri,
A. J. Soroka Eds., Amsterdam, Elsevier, 2005: 417-422.
4. Carmo-Silva S, Alves AC. Detailed design of product oriented manufacturing systems. Proceedings of
Group Technology / Cellular Manufacturing 3rd International conference – 2006, J. Riezebos and
Ir. J. Slomp Eds., University of Groningem, Holland. 2006: 44, 260-269.
5. Chan HM, Milner DA. Direct Clustering Algorithm for Group Formation in Cellular Manufacture.
Journal of Manufacturing Systems. 1982: 1: 1.
6. Cochran DS., Arinez, JF., Duda, JW., Linck J. A decomposition approach for manufacturing system
design. Journal of Manufacturing Systems, 2001/2002: 20: 6;: 371.
7. Irani, SA. Handbook of Cellular Manufacturing Systems. John Wiley & Sons, 1999.
8. McAuley, J. Machine grouping for efficient production. Production Engineer 1972: 51-57.
9. Silva SC, Alves AC. Design of Product Oriented Manufacturing Systems. In Knowledge and
Technology Integration in Production and Services, V. Marik, L Camarinha-Matos and H
Afsarmanesh, Eds. Kluwer Academic Publishers, 2002: 359-366.
10. Suh NP. The principles of Design. Oxford University Press, 1990.
11. Suresh NC, Kay JM. Group Technology and Cellular manufacturing. Eds., Kluwer Academic
Publishers, 1998.