The Brimacombe Memorial Symposium, Poster Proceedings,( Oct. 1-4,2000, Vancouver ) pp.255-264
Knowledge management for pre-production processes
Yoshiyuki Nagasaka
Faculty of Business Management
Osaka Sangyo University
3-1-1 Nakagaito, Daito-shi
Osaka, Japan 574-8530
ABSTRACT
Most of pre-production processes in manufacturing consist of many non-routine
tasks and depend on the peculiar characteristic techniques of skilled workers. Not only
explicit data but also tacit knowledge is important. Although skillful engineers are
decreasing, the engineering quality of pre-production processes must be kept and
improved more and more. Thus, it is necessary to share and inherit important information
naturally.
In this study, a software package for the knowledge management of preproduction processes has been developed by considering practical requirements. The
objectives of the software are to achieve a more efficient and reasonable manufacturing
design as well as to inherit traditional technologies. An activity model is also considered.
The activity model includes task models structured as a tree and is related to background
information. For instance, a drawing does not adequately indicate to know why and how
the shape, dimensions and materials are determined.
Here, design background
information is stored in the database and linked to each item or geometric object in the
activity model. It is helpful to verify the design conditions and extract the best practice
later. This software is shown to be useful in practical applications.
INTRODUCTION
Most companies understand that information technologies are useful in improving
quality and productivity (1). For instance, a database is very useful for retrieving suitable
data. Groupware is convenient in constructing a collaboration environment. CAD is used
to achieve efficient drawings and CAM is popular for accurate manufacturing. Moreover,
some computer simulations are practically used to predict physical phenomena of
production processes (2-4). If these digital technologies are used well, it is possible to
optimize pre-production processes, but how to use them is different depending on the
company or engineer. The know-how for the specific production process is still
important.
Recently knowledge management has attracted much attention, because
knowledge has become one of the most important management resources. It is said that
there are two types of knowledge : explicit and tacit knowledge (5). Operation manuals,
documents on technical standards and drawings belong to explicit knowledge. Tacit
knowledge such as know-how, paradigms and customs cannot not be represented or
shaped very easily. However, sometimes tacit knowledge must be changed to explicit
data in order to make each clear in business applications. Here, we must consider how
important tacit knowledge can be efficiently transformed into explicit knowledge. If
possible, the members in business can use such knowledge in the same manner. This
situation is then helpful for creating new ideas.
The modeling of business activities is very important for knowledge management.
In this study, a knowledge management tool for pre-production processes has been
developed by considering an activity model (6). Generally, pre-production processes
include a lot of non-routine work and depend upon inherent technologies of the person in
charge. There is a great deal of tacit knowledge. It is necessary to transform the tacit
knowledge into explicit knowledge by using a natural way of sharing and inheriting
important information. The objectives of this study are to achieve a more efficient and
reasonable pre-production design as well as to inherit traditional technologies.
PROBLEMS AND BACKGROUND
The cycle of knowledge in business is well known as shown in Figure 1. Tacit
knowledge such as know-how and paradigm spreads by daily communications.
Sometimes tacit knowledge is expressed in documents and figures. Such explicit
knowledge can be summarized and combined together. Namely, different shaped
explicit knowledge is generated. This explicit knowledge is very helpful in creating new
ideas in the next step. If tacit knowledge is continuously and widely changed into
explicit knowledge in a company, the engineers can retrieve useful information more
easily.
2
Tacit
Tacit Knowledge
Knowledge
↓
↓
Tacit
Knowledge
Tacit Knowledge
Tacit
Tacit Knowledge
Knowledge
↓
↓
Explicit
Knowledge
Explicit Knowledge
Explicit
Explicit Knowledge
Knowledge
↓
↓
Tacit
Tacit Knowledge
Knowledge
Explicit
ExplicitKnowledge
Knowledge
↓
↓
Explicit
Knowledge
Explicit Knowledge
Figure 1 - Cycle of knowledge in business
The current problems for pre-production processes are summarized as follows.
(a)
(b)
(c)
(d)
(e)
Know-how is not expressed explicitly.
Process planning standards are not sufficient.
Inheritance of know-how is difficult.
It is not easy to have stable high quality.
It takes a lot of time to draw up a plan and make many documents.
Manufacturing engineers should engage in creative activities as much as possible,
but the time of creative activity is generally limited to under 20% of a working day. They
spend more time looking for necessary information and have many of meetings.
Generally speaking, process planning depends on the peculiar characteristic
know-how of the engineer because each engineer has different tacit knowledge. In other
words, there is a problem because the ideas for new process planning are limited
depending on the experience or communication of the engineer. This is due to the fact
that it is not easy to extract enough explicit information from a drawing and documents.
Accordingly, background information on each decision should be gathered in the database.
Modeling is a very useful technique for
changing tacit knowledge into explicit
knowledge. Figure 2 shows the four models at
minimum needed for pre-production processes :
geometric, mathematical, data, and activity
model.
Geometric model
Activity model
Database
A Geometric model can be generated by
Mathematical model
Data model
using three-dimensional CAD. It can include
some properties such as volume, thickness and Figure 2 - Models for pre-production
specifications of machining. We can consider processes
the manner of production with a geometric
model. Mathematical models of physical phenomena are used for computation. For
example, a heat conduction model including latent heat during solidification is
represented as finite difference equations that can be implemented on a computer. A
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geometric model is usually divided into many small finite elements that are applied to the
mathematical model. A mathematical model is very useful for engineers who want to
know what happens in manufacturing processes. In addition, a data model is necessary in
business to store and control lots of data related to products. We must know a customer's
name, delivery time limit and other requirements. During pre-production processes,
additional data such as cost estimation and manufacturing schedules are stored and
controlled. On the other hand, an activity model is important in expressing purposes,
tasks, entities, methods and so on (6). An activity model is similar to a business model.
A business model is constructed with business objects. Thus, a business model is the
representation of a thing active in the business domain, including at least its business
name and definition, attributes, behavior, relationships and constraints (7).
REQUIREMENTS FOR AN INFORMATION MANAGEMENT SYSTEM
Considering the problems mentioned above, we can summarize the requirements
for a knowledge management system of pre-production processes as follows. Both a data
and an activity model should be included in the system.
(a) Data in various forms like figures, images and CAD drawings can be easily
accumulated and retrieved.
(b) Pre-production activities should be clearly represented and linked to the
database of background information (7) .
(c) Necessary data must be gathered with less operation load.
(d) Important information should be unitarily and centrally controlled for the
company. In addition, other types of information should be organized and
distributed to individual persons in charge or groups of some members.
The database should include product data and background information. Namely,
the system must accept different data formats such as numerals, texts, formulas,
spreadsheets, graphs, images, CAD data and rule bases. It is important to achieve data
consistency using a database management system. Moreover, some convenient tools are
necessary to transform the data written on paper into digital data and to store background
information. An appropriate methodology for quick retrieval is also necessary. A
concept mining engine is considered to be one of the most powerful tools for searching
for proper information represented in a natural language. On the other hand, it is effective
to give the shortest answers to some questions to achieve a final goal.
First, the database should be helpful for individual engineers. Secondly, it should
be utilized as shared information for several engineers in the same company. Common
information such as a design standard should be managed intensively. However, the
knowledge base including decision-making processes may be stored individually. After a
while, effective data for individuals should be shared with the same group members. The
preparation of a network environment is indispensable for this purpose.
4
MULTIMEDIA DATABASE
A multimedia database is constructed. The database includes product data and
background information, namely, not only a lot of entities such as production process
conditions, cost data and customers information but also their attributes, attribute values
and relationships. Because we must store various data in a computer, the system must
accept different data formats such as numerals, texts, formulas, spreadsheets, graphs,
images, CAD data and rule bases, as shown Figure 3. It is important to achieve data
consistency so that a database management system is necessary. If there is still much
information written on sheets of paper, a convenient tool is prepared to transform the data
drawn on paper into digital data. For instance, this tool can easily change a graph drawn
on a sheet of paper into digital data, as shown in Figure 4.
Photograph
CAD
Table
ねずみ鋳鉄品規格表 -ＪＩＳ Ｇ ５５０１主要肉厚範囲[mm]
供試材の鋳放
引張試験
たわみ
かたさ
し直径[mm]
[kg/mm2]
最大荷重[kg]
[mm] [Hb]
種類
記号 以上 以下
以上 以上
以上 以上
ねずみ鋳鉄品１種
ＦＣ１０4
50
30
10
700 3.5 201
ねずみ鋳鉄品２種
ＦＣ１５4
8
13
19
180
2 241
8
15
20
17
400 2.5 223
15 30
30
15
800
4 212
30 50
45
13
1700 6 201
ねずみ鋳鉄品３種
ＦＣ２０4
8
13
24
200
2 255
8
15
20
22
450
3 235
15 30
30
20
900 4.5 223
30 50
45
17
2000 6.5 217
ねずみ鋳鉄品４種
ＦＣ２５4
8
13
28
220
2 269
8
15
20
26
500
3 248
15 30
30
25
1000 5 241
30 50
45
22
2300 7 229
ねずみ鋳鉄品５種
ＦＣ３０8
15
20
31
550 3.5 269
15 30
30
30
1100 5.5 262
30 50
45
27
2600 7.5 248
ねずみ鋳鉄品６種
ＦＣ３５15 30
30
35
1200 5.5 277
30 50
45
32
2900 7.5 269
Image
Table
Equation
Database
Graph
Graph
Equation
Movie CAD
ESH=(2HC-P2)/2C
PKC=3.5H-2.5H2+C
Text
knowledge
Decision table
A decision table including calculated index
Tolerance M aximum size
Defect level M onthly production
(1111)
≧level3
≦20
(111)
(1112)
≧800
＞20
Normal
(1121)
≦level2
≦30
(11)
(112)
(1122)
＞30
(1211)
＜800
≦30
(1)
(12)
(121)
(1212)
＞30
Severe
30
(2111)
≦
(2)
(21)
(211)
(2112)
＞30
Memo
M aterial of core box
Wood (11111)
Resin (11121)
Resin (11211)
M etal (11221)
Resin (12111)
M etal (12121)
Resin (21111)
M etal (21121)
Riser Design
・
Objectives of riser
Risers feed shrink of
molten metal during
solidification. Pouring time (s)
Figure 3 - Summary of multimedia database.
Weight (kg)
Figure 4 - A tool to convert graphs written on paper to numerical data
In this system, information on manufacturing, cost, process planning, order
information, customer and cooperative corporation are considered as entities. Besides
data such as the product number, product name and material name expressed with
numerals and text, drawings and photographs of a product, a mold design and jigs as well
as spreadsheets, graphs, formulas, memos related to the pre-production processes are
5
considered as attributes. An RDB (relational database) has been adopted to implement
this data model. For drawings, photographs, spreadsheets, graphs, formulas and rule
bases, the filenames are stored as a general multimedia database. Some anchors can be
set to be in CAD or image data and linked
Memo
to other data such as comments and
May 1, 1999
photographs, as shown in Figure 5.
Heat treatment was performed.
Photograph
Although a rule base may not be
able to cope with all of the knowledge, it is
considered necessary to be the most
fundamental and practical expression
approach for a knowledge base. A
convenient tool for creating decision tables
in the end user computer environment has
also been developed for typical expert
diagnostic systems. Figure 6 shows an
example of the decision tree used to select
material for a core mold. In the system,
decision tables ( such as TableⅠ) can be
created with MS-Excel and automatically
transformed into decision trees. The user
can directly modify either the decision
table or the decision tree. After a
decision table is fixed, a GUI (Graphical
user interface) for questions and answers
is executed as shown in Figure 7 . Each
question and answer can be easily linked
to other information such as pictures and
graphs stored in the database.
日付：平成８年５月１日
・鎖線部高周波焼き入れを実施する
・機械加工後残るように
From 1173 K to oil temperature.
鋳造すること
Mechanical properties;
・機械的性質
Yield strength; 92 kg/mm2
(1)引張強さ 95kgf/㎜
Impact strength; 3.5 kgf・m
(2)衝撃値 3.5kgf･m/㎝
Inspection
for outside was done.
・歪み取りを実施
…
・・・・・・・
欠陥名：鋳張り（脈状鋳張り）
May 9, 1999
鋳型 ：生型
Flash
発生日：５月１日
Green sand mold
備考 ：膨張すくわれも同時発生し
Several area with scab defects
ている
Figure 5 - Anchors linked to other data
Table Ⅰ - A decision table including
calculated index for Figure-6
Tolerance Maximum size Defect level
≧level3
≧800
≦level2
Normal
＜800
-
-
-
Severe
Monthly
Material of
production core box
≦20
Wood
＞20
Resin
≦30
Resin
＞30
Metal
≦30
Resin
＞30
Metal
≦30
Resin
＞30
Metal
Diagnosis
Knowledge
Questions
External appearance
Select the answer !
Diagnosis
Explanation
Fin , Flash
1. Fin , Flash
1. Fin , Flash
2. Shrinkage
3. Crack
4. Defect on surface
5. Short shot
6. Dimension error
7. Inclusion
Zoom up
down
Clipping
The defects occurred
on casting surface
near the boss.
Close
Explanation
Next
End
Figure 6 - An example of decision tree
Figure 7 - Example of diagnosis for
casting defects.
6
KNOWLEDGE MANAGEMENT TOOL BASED ON ACTIVITY MODEL
Activity Model
The activity model proposed in this study consists of task models that are
structured as a tree. Each task has design items to be fixed, and some background
information is related in the database is related to each design item. Documents, drawings
and computer files are created through several tasks. The values of design items are
components of the documents and drawings. We can easily find the foreground
information by looking at the results. However, it is usually very difficult to learn why
the value was fixed. The background information is important for determining how the
engineers make a decision. If the design background information is stored and linked to
each object in the drawing, it helps us to verify design conditions. The methodology in
implementing the activity model on a computer should be discussed.
A GUI has been designed for the activity model and is named "design palette" as
shown in Figure 8. There are three windows showing a task tree, design items and
background information. If a task is selected, design items to be determined are shown in
another window. Suitable values or comments must be input for each item. We fix the
values by navigating in the background information window. There may be several
candidates as background information such as a technical standard table, a numerical
equation, a drawing of similar
product and so on. The operator can
see all candidates and choose one of
Task tree
Design item Value
1.Pppp
them.
If there is no good
2.Qqqq
background information, he/she can
3.Rrrrr
fix the value as he/she wishes. Then,
he/she can install the method as new
Background information
1.Aaaaa
background information and link it
2. Bbbbb
1.Aaaaa
to the item. Even the name of
3. Ccccc
design items may be changed by the
operator. Namely, the operator can
modify and arrange the activity
Figure 8 - GUI for activity model
model dynamically.
A general business object includes entities and methods as a capsule (9). If you
see a business object, some of the entities should be inputted at the operation. Others may
only be referred to. Methods such as small calculation modules are usually used to fix
some values of the entities. The capsules must be designed and implemented beforehand.
Only system engineers can modify the capsules. Here, the background information
includes entities and methods to refer to. The entities and methods related to the design
item can be automatically determined with the correspondence of key words in this
system. In addition, a natural language treatment by using concept mining engine is used
to pick candidates for text data. However, the candidates may not be suitable information
for the design item. If the operator opens and sees the background information, the count
7
number increases. If the background information is actually used to fix the values of the
design item, another count number increases. The count numbers show how useful it is.
Sorting with the count numbers is useful for seeing which background information is
popular.
Let's look at the case of a die design. The die designer must fix geometric objects
in a drawing. The geometric objects mean risers, cores and runners as shown in Figure 9.
A class and attributes for each object are defined. Examples of attributes for the class of
riser are type, diameter, height and so on. If a specific riser is designed, an instance is
created. This kind of data generation for objects can be performed through the activity
model mentioned above. The task is to fix an instance. If a parametric model of geometry
can be defined for each class in CAD, a specific geometry is automatically drawn as a
representation of the instance.
Input:Drawing
Input:Drawing of
of aa product
product
Output:Drawing
Output:Drawing of
of aa Die
Die
Spru
e
Die
Design
er
Runner
Gate
Product
Object
Finish
、
Finish allowance、
allowance、
、
Draft、
、
、
Draft、
、Riser、
Riser、
、
Runner/Gate、
、
、
Runner/Gate、
Core、
、Core、
、
Parting
Parting line
line
・・・
・・・
Class
Tasks
［
］
［Runner］
Runner］
］
Type
Type
Height
Height Attribute
Attribute
Width
Width
［
］
［Draft］
Draft］
］
Position
Position
Angle
Angle
Instance
Instance
Design items
No.
［
］
No.A0011［
A0011［
［Runner］
Runner］
］
L-1
L-1
3.5
3.5mm
mm Attribute
Attribute
4.5
4.5mm
mm
values
No.
［
］
No.A0012［
A0012［
［Draft］
Draft］
］
Upper
Upper
3.2
3.2
Figure 9 - Relations between object, class and attribute.
Knowledge Management Tool
An integrated system has been
developed in which the activity model,
Activity
multi-media database, and CAD are
Activity Model
Model
MMDB
(Task tree model)
combined as a knowledge management
tool (Figures 10 and 11).
Several
CAE
functions
have
been
developed
CAD
corresponding to the requirements
Figure 10 - Concept of a knowledge
mentioned above. (1) Improvement of
management tool.
drawing efficiency : automatic
parametric, semi-automatic drawing,
(2) Improvement of information retrieval efficiency : retrieval and registration of
multimedia database during CAD operation, (3) Clarification of design background
8
information and transfer: design
palette (registration of tasks, design
item
and
related
background
information), log file (recording of
design history).
･Parametric drawing Design value
･Note
<Design
CAD
Palette>
Task Detailed design item
Database
Design background
information
The procedure is described as
follow. An example of a die design is
Log File
(Design history)
shown in Figure 12. When a task
(runner, core, etc.) is selected, detailed Figure 11 - Schematic drawing of a knowledge
design items (type, height, diameter,
management tool.
etc. ) are inputted. Select an item to
fix its value. Several candidates among a lot of design background information are
prepared below in the design palette. If the necessary design values are fixed through a
technical standard, parametric drawings or notes are automatically inserted in a CAD
figure. The design palettes should be set initially by end users and can be modified at any
time. The activity model grows as the end user utilizes it. The log file of all operations is
very useful because it shows how the designer decides the design values, and how often,
and which design background information is used by all members. All contents of the
operation are accumulated as log information and determined values are saved as a part of
product information. If you can statistically compare the quality and cost of a casting
product with the design procedure, the best or a better practice may be found.
Selection of a task
Selection of an item
Input of final values
Parametric
drawing
Drawing by CAD
Reference of standard
Figure 12 - Example of parametric drawing.
The system developed here has already been applied to several practical cases.
Figure 13 shows examples of a practical design palette. In practical use, the first motive
of this system is to save the cost for pre-production processes by reducing completion
time. A lot of different types of data can be stored on a personal computer and the
necessary data can be found quickly. The data is useful for quality control. Some
documents are automatically completed and printed out with adoptive forms through the
9
operation of this system.
Some data in the database can
be related to report forms. It
is easy to arrange the report
form depending on the
requirements.
Questions
must be asked to the designer.
Even the engineer does not
remember everything about
why and how the values were
fixed. This system helps us
understand more about the
details of the drawing.
Task tree
Design item
Model　A
Model B
Back ground information related to each design item
Figure 13 - Design palette of practical work
SUMMARY
A knowledge management tool has been developed. This tool includes an activity
model related to a data model. We have designed the data model in consideration of
various data forms such as numerals, texts, formulas, spreadsheets, graphs, images, CAD
data and rule bases. Design background information was considered as very important
information in the successful transfer of technical know-how. As a result, we found that
this tool is very useful for practical use.
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4.
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