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Database Development for Supporting Machining of Prismatic Components*
A. M. Shaharoun 1, A. A. Razak 2, M. I. Jambak 3
Faculty of Mechanical Engineering
Universiti Teknologi Malaysia
Locked Bag 791, 80990, Johor
Phone: +60 - 07 - 5504566
Fax: +60 - 07 – 5566159
1
E-mail: [email protected]
E-mail: [email protected]
3
E-mail: [email protected]
2
ABSTRACT
Machining processes are operations of metal removal by turning, shaping, planing and milling. Machining processes
are common within a Flexible Manufacturing System (FMS) and carried out by computer-controlled operations. In
order to operate efficiently, an FMS requires a complete set of information to assist its operation. Therefore the design
of the information system has to be performed taking into consideration all the functions and entities that operate within
an FMS. The modelling work in this research will be on capturing the activities on the shop floor focusing on the
machining of prismatic components. IDEF suite of modelling software will be used to come up with the functional and
information model. Issues of architecture, for instance the flexibility and adaptability of the database are highlighted
during the modelling phase. The approach adopted in this research is to start the development work using a relatively
small-scale database management system (DBMS) and later expanding the scope and migration into a wider scale
DBMS. The database will be of assistance to researchers and companies who use extensive machining processes for
their operations and who intend to integrate their operation into an FMS. Such a database will also act as a precursor
for a more extensive database such as those required to operate a Computer Integrated Manufacturing (CIM) system.
Keywords
Database, Information System, Flexible Manufacturing System, Prismatic Components, Modelling, Computer
Integrated Manufacturing
methodology and tools used in developing the database
for supporting machining of prismatic components.
INTRODUCTION
Industry is today characterised by automation.
Engineering processes such as machining, fabrication etc
are mainly performed by computer-controlled machines
that perform the operations automatically and often
integrated into a system such as FMS.
As a computer-controlled system, an FMS is an
information-driven system. The attributes of an
information system that impact the operation on the shop
floor are the quality of information, reliability,
consistency and concurrency control, speed of operation,
and adaptability (Veeramani et al., 1993).
One of the challenges in developing the database is to
organise all the data into a useful, accessible and logical
form (Hannam, 1996). Two strategic approaches for
tackling this problem are creation of the information
model that maintain its characteristic of wide
applicability and flexibility, and use of a CIM
architecture (Hannam, 1996 : Singh, 1997). The
database in this paper is developed based on the initial
information architecture.
This paper describes the database state-of-art, the
requirements of the database, the strategy, the
*
DATABASE STATE-OF-ART
A database is a place where data can be stored and
retrieved. A database is controlled by a software system
that performs the function of defining, creating, and
revising the database called database management
system (DBMS) (Singh, 1997).
Vernadat (1994) gave at least five standard requirements
of a database:
- Data independence: Physical data-storage aspects
are independent from logical data description and
manipulation, and are unknown from user
applications.
- Data sharing: Data can be shared and accessed
concurrently by different user and/or applications.
- Controlled data redundancy: The same information
must be stored once.
- Data integrity and security: Rules can be expressed
and verified to ensure that the state of the database
is semantically correct.
- Ad hoc query facility: Queries on data can be
expressed and executed to provide answers to
questions formulated by application or on-line users
Shaharoun, A.M., Razak, A.A., Jambak, M.I. (1999), “Database Development for Supporting Machining of Prismatic Components “, In
Proceeding of World Engineering Conference ’99, Kuala Lumpur, 19th – 22nd July 1999, pp. 483-488
The concept of database is data integration based on a
three-schema model (Hsu, 1994 : Hannam, 1996 : Singh,
1997), they are briefly described as below:
- Internal schema: Represents the physical
organisation and storage of the information.
- External schema: Describes the use of information.
Users view only the portion of data that concerns
them in their own preferred ways as if these data
were structured exclusively for their software
environment.
- Conceptual schema: Represents a composite view of
a common pool of shared data. The integration
takes place with the conceptual schema, which is the
community representation of the consolidated data,
sources and is precisely the heart of the database
model.
characteristics (i.e., extendibility, expandability, and
adaptability). The information architecture is needed in
response to the evolutionary nature of integrated
manufacturing, because the changes in requirements in
integrated manufacturing will inevitably affect
dependency relationships and information flows among
inter-operating functional modules in the system. Figure
1 shows the role of information architecture for
developing the database to control the FMS:
However, the architecture is a conceptual one and not a
concrete physical property of a system. Thus, the
architecture should be visualised by means of a symbolic
model to represent the system.
Depending on how the conceptual schema is
constructed, there are four major types of databases
(Hsu, 1994 : Elmasri et al., 1994): hierarchical, network,
relational, and object-Oriented
There is another type of database but not so common at
present called Object-Relational database. The database
is founded based on the advantages of relational
database and object-oriented database.
The relational database is the mostly commonly used
and well-supported form of database.
Hsu (1994) found that relational and object-oriented
databases are more flexible than others types.
Furthermore, Singh (1997) described the potential of
relational type as follows below:
1. Ease of use because the visualisation and clarity of
data is represented by two-dimensional tables
2. All data is viewed in tables, thereby allowing easy
data manipulation and query via Structured Query
Language (SQL)
3. With the relational operations, a standardised and
effective way of decomposing and recomposing
relation is provided. This approach enables the
incremental building of larger systems module by
module
4. Security controls can be easily implemented where
security authorisation will relate to relations to
protect company sensitive attributes
5. The
relational
model
support
dynamic
reorganisation (i.e. extension and modification to
the structure) of the database without affecting
existing application
6. Generally supported by high level non-procedural,
set-oriented languages, such as 4GLs (fourth
generation languages) to enable flexible access,
management and presentation of data stored in the
database.
INFORMATION ARCHITECTURE
The information architecture shows the subject area of
information needed and used by an enterprise, and may
include the entities and the relationships of those entities
within the subject areas considering the architecture
Figure 1. The role of Information Architecture
In this research work, the functions and the information
needs in the machining operation are modelled by using
IDEF methodology before the database tables are
created.
IDEF
“IDEF” is an acronym for the ICAM-Definition
methodology
–
(Integrated
Computer-Aided
Manufacturing). The IDEF methodology was developed
by the US Air Force’s ICAM program in the early
1980’s (Ranky, 1990 : Ang et al., 1989, 1994). IDEF
methodology is a group of methodologies, which are
used for modelling of particular aspects of a system
(Sarkis et al., 1994 : Vernadat, 1996). IDEF™ integrated
software by Meta Software Corporation was being used
in this research. The IDEF™ suites provide IDEF0 for
modelling the functions and activities of the system, and
IDEF1x for developing the conceptual relational data
model.
In IDEF0 the functions are represented by blocks and
linked together through inputs, outputs, controls and
mechanisms (ICOM). Functions can be decomposed into
sub-functions (Wu, 1992 : Sarkis et al., 1994 : Ang et al.,
1994 : Vernadat, 1996). Figure 2 illustrates a block of
an IDEF0 model.
tools, and work-holding tools) of manufacturing
information respectively Bugtai (1997). Figure 3 shows
the manufacturing data structure.
Manufacturing Information
Process
Machining
Resources
Fixturing
Figure 2. An IDEF0 Diagram
To model the information system, every entity in
IDEF1x, is represented by a box and given a unique name
with a parent entity having a relationship with a child
entity.
DATABASE REQUIREMENTS FOR
SUPPORTING THE MACHINING OF
PRISMATIC COMPONENTS
The database for supporting the machining of prismatic
components should fulfil the minimum requirement that
was given in the previous section. Thus, the database
could facilitate the frequent updating of information to
increase the speed of operation. To do so the database
should be able to capture all relevant information
accurately and completely. It must be capable of
meeting the short-term changes according to the need of
production planning and should require minimal cost for
long-term changes of a manufacturing system.
The database should incorporate the process (machining
and fixturing) and the resources (machine tools, cutting
Machine
Tool
Cutting
Tool
Workholding
Tool
Figure 3: Manufacturing Data Structure
(Bugtai, 1997)
The database should support shop floor control
operations to manage and control all the manufacturing
activities, which take place at different locations on the
shop floor. The information that is supplied by the
database required to execute these activities has to be
delivered to the right location.
RESULTS
Machining of Prismatic Components
Functional Model Using IDEF0
System
Figure 4 illustrates the third level of a manufacturing
activities functional model. It is decomposed from the
top level, and if necessary, it can be further decomposed
to get more detailed model.
Figure 4. Manufacturing Activities
The system to be modelled assumes a small batch
manufacturing system and the machined components in
the system are defined to be prismatic components.
According to Tiemersma’s (1992) reference model of
Flexible Manufacturing Cell – where the manufacturing
activities take place –there are at least five
manufacturing activities on the shop floor: tooling,
fixturing, material storing and retrieving/loading,
transport system activities, and workstation activities.
Every activity or the function is capable of being
decomposed to the lower level. For example, in the
tooling activity, tool identification, tool assembling and
loading/unloading to the transport system activities are
located in the lower level of the model.
Information Modelling Using IDEF1x
In determining the information flow, the IDEF0 function
was analysed. The components in the IDEF0 blocks, i.e.
input, control, output and mechanism (symbolised by an
arrow) give an understanding of the information that
needs to be captured.
Figure 5 shows an example of the tool information
model based on the IDEF0 block number A41 (Tooling).
The constructed model shows the entities, the attributes,
and the relationships from the tool point-of-view.
Figure 5. Tool Information Model
The tool entity was created first, and then its children. In
this case, the children of the tool entity includes tool
assembly, tool-holder, tool parameter (which is shown in
figure 5) and other entities like shank, cutter-edges, etc.
Database Tables Construction
CREATE TABLE TOOL
(
tool_id
CHAR(21) NOT NULL,
tool_name CHAR(20) NULL,
supp_code CHAR(10) NULL,
picture
CHAR(50) NULL
);
CREATE UNIQUE INDEX IXTOOL ON TOOL
(
tool_id
ASC
);
CREATE TABLE TOOL_ASSEMBLY
(
insert_code
CHAR(10) NULL,
Screw_code
CHAR(10) NULL,
tool_id
CHAR(21) NOT NULL
);
CREATE UNIQUE INDEX IXTOOL_ASSEMBLY ON
TOOL_ASSEMBLY
(
tool_id
ASC
);
CREATE TABLE TOOL_HOLDER
(
holder_code
CHAR(13) NULL,
tool_id
CHAR(21) NOT NULL
);
CREATE UNIQUE INDEX IXTOOL_HOLDER ON
TOOL_HOLDER
(
tool_id
ASC
);
CREATE TABLE TOOL_PARAMETER
(
tool_diameter
DECIMAL NULL,
tool_length
DECIMAL NULL,
length_L4 DECIMAL NULL,
length_Lc DECIMAL NULL,
hold_diameter
DECIMAL NULL,
tool_model
CHAR(10) NULL,
tool_id
CHAR(21) NOT NULL
);
CREATE UNIQUE INDEX IXTOOL_PARAMETER ON
TOOL_PARAMETER
(
tool_id
ASC
);
Figure 6. IDEF1x SQL Commands
system can be easily refined into greater detail until the
model is as descriptive as necessary for the decisionmaking task at hand. The hierarchical nature of IDEF0
facilitates the ability to construct (AS-IS) models that
have a top-down representation and interpretation, but
which are based on a bottom-up analysis process. In fact,
In the implementation stage, the information model is
used to create the tables for the database. There are two
ways of creating the tables. The first option is to directly
create the table using table wizard facility in the DBMS.
The second option is export the IDEF1x model to the
SQL file and execute the commands in the file to create
the tables. The SQL commands shown in figure 6 below
are created by using the export facility in IDEF1x.
Figures 7 and 8 show the database table and its user
front-end respectively.
DISCUSSIONS
The primary strength of IDEF0 is that the method has
proven effective in detailing the system activities for
function modelling. The description of the activities of a
Figure 7. The Database Table
Figure 8. Database Front-End
one of the observed problems with IDEF0 models is that
they often are so concise that they are understandable
only if the reader is a domain expert or has participated
in the model development.
database system is capable of being scaled up to a larger
system such as those required by a CIM system.
The strength of IDEF1x lies in its roots and the weakness
of IDEF1x is that the modeller must be experienced in
order to create good models.
This research is conducted under IRPA project vote
number 72091 for the Faculty of Mechanical
Engineering, Universiti Teknologi Malaysia.
One of the problems of database development is the nonuniformity of SQL commands for different system. For
example, figure 9 below shows the difference between
IDEF1x and Oracle DBMS SQL commands for the same
set of instruction.
REFERENCES
IDEF1x SQL:
CREATE TABLE TOOL_ASSEMBLY
(
insert_code
CHAR(10) NULL,
Screw_code
CHAR(10) NULL,
tool_id
CHAR(21) NOT NULL
);
Oracle SQL:
CREATE TABLE TOOL_ASSEMBLY
insert_code
CHAR(10) NULL,
Screw_code
CHAR(10) NULL,
tool_id
CHAR(21) NOT NULL;
Figure 9. Differences in SQL Commands
CONCLUSION
This paper has described the requirements for a database
for supporting the machining of prismatic components.
The functional and information models were developed
using IDEF methodology. The database is generic and
will prove useful to researchers and companies who
intend to or are already implementing automated
machining systems. The system architecture is capable
of operating in a highly dynamic and frequently
changing manufacturing system environment. This
ACKNOWLEDGEMENT
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