DEVELOPMENT OF A FEATURE LIBRARY FOR THE EXTRACTION OF
MANUFACTURING FEATURE AND MANUFACTURING INFORMATION
Hendry Muljadi1, Hideaki Takeda1, Koichi Ando2
1
National Institute of Informatics, Japan2
Shibaura Institute of Technology, Japan

ABSTRACTIn a manufacturing feature-based process planningsystem, for the generation of process plans, it is necessary
to develop a feature library that consists of pre-definedmanufacturing features and the manufacturing
information to create the shape of the features. This paper
describes the development of a feature library for aprocess planning system. The feature library is developed
to enable the automatic extraction of manufacturingfeatures with their proper manufacturing information thatwill lead to the generation of process plans. In this paper,
the implementation of Wiki for the development of thefeature library is proposed.
1. INTRODUCTION
Computer Aided Process Planning (CAPP)
integrates the automation of product design with that ofmanufacturing by linking the design representation ofComputer Aided Design (CAD) systems with the
manufacturing process representation of Computer Aided
Manufacturing (CAM) system. In order to allow the CAD
system to interface with the CAPP system, featuretechnology has emerged as the enabling technology toconvert CAD product data to manufacturing information.
Many different approaches have been developed to extract
features from the CAD product data (Subrahmanyam2002).
In a manufacturing feature-based process planningsystem, for the generation of process plans, it is necessary
to develop a feature library that consists of pre-definedmanufacturing features and the manufacturing
information to create the shape of the features (Kanamaru
et al 2004). The manufacturing information consists of therequired machine and tool data, the estimated cost andtime data, etc (Scallan 2004). Considering the rapid
progress of manufacturing technologies, a feature libraryneeds to be developed in a way that is easy to modify or
to customize.
On the other hand, in the context of collaborationon the web, Wiki has proven itself to be an easy to modify,
user-friendly interface. For example, the community of
Wikipedia.org, the free content encyclopedia is becoming
larger and larger. There have been more than 600,000
people who gave their contributions, either by creating or
editing articles in Wikipedia. Wiki is a discussion
medium, a repository of ideas and a tool for collaboration.
It is a simple publishing system that is easy to learn andquick to use (Leuf et al 2001). In Wiki, people can createor edit a Wiki page using a simple syntax to write content.
So, it is normal to make an assumption that an extended
Wiki will be useful for the development of a featurelibrary which can be easily modified.

In this paper, the modification of MediaWiki, theWiki software used for the Wikipedia, and theimplementation of the modified MediaWiki for thedevelopment of the feature library is described.
The structure of this paper is as follows. Section 2
discusses the need to consider the designer’s intention for
the realization of the automatic extraction of
manufacturing features with their proper manufacturing
information. In section 3, the structure of the featurelibrary to enable the automatic extraction of
manufacturing features with their proper manufacturing
information is described. Section 4 describes themodification of MediaWiki and the implementation of themodified MediaWiki for the development of the featurelibrary. Section 5 states the conclusions drawn from theresearch.
2.

CONSIDERINGTHE
DESIGNER’SINTENTION
FOR
THE
AUTOMATICEXTRACTIONOFMANUFACTURING
FEATURES
WITH
THEIR
PROPERMANUFACTURING INFORMATION
A manufacturing feature can be defined simply as ageometric shape and its manufacturing information tocreate the shape. However, most feature recognition
methods only deal with the automatic extraction ofgeometric shape from the CAD product data, and do notdeal with the automatic extraction of proper
manufacturing information to create the shape.
For the extraction of proper manufacturing
information to create the shape of the manufacturingfeatures, it is important to understand the designer’s
intention. For example, a thru-hole feature may require acylindrical grinding to create the shape, while the otherthru-hole feature may require threading to create theshape, depending on why the designer designed thegeometric shape.
In this research, the designer’s intention isrepresented by the functions of the face elements that
construct the features. The face element is defined as ageometrical entity that is bounded by a set of edges. The
functional data of the face elements can be described as
basic function, mechanism utilized for realization of thebasic function, and condition and direction of the motion.
The detail explanation of the functional data elements isgiven in other reports (Yoshikawa et al 1987) (Ando et al1989). Table 1 shows the contents of the functional
properties of face elements that are used in this research.
Fig.1 shows an object with a screw thru-hole. Table
2 shows the representation of function of the faceelements that construct the screw hole. The basic function
is fixation of motion. The mechanism utilized forrealization of the basic function is bolt-only. The
condition and direction of the motion is stationary-object.
Fig.2 illustrates that by dealing with the geometrical
data and the functional data of the product design data, theautomatic extraction of manufacturing features with theirproper manufacturing information can be realized(Muljadi et al 2004).
Table 1. Contents of functional properties
Basic
Function

Mechanism utilized
for realization of thebasic function

Transmissionof motion

1: friction-mech.
2: gear-mech.
3: link-mech.
4: cam-mech.

Constraint of
motion1: rigidity-mech.
2:ball-bearing-mech.
3: sliding-mech.

Fixation of
motion1: bolt-and-nut
2: bolt-only
3: friction-mech.
4: bearing-fit
5: key-fit
6: rivet-fit
7: shrinkage-fit

Condition anddirection of the motion
1: liner
2: smooth-liner
3: very-smooth-liner
4: round
5: smooth round
6: very smooth round
1: liner
2: weak-radial
3: strong-radial
4: weak-thrust
5: strong-thrust

1: stationary-object
2:revolutionary-object

Screw Thru-Hole

Fig. 1 An object with a screw thru-hole
Table 2. The representation of function of the faceelements that construct the screw hole
Basic
Function

Mechanism utilized
for realization of thebasic function

Condition anddirection of the motion

Fixation of
motionbolt-only

stationary-object<Design System>
Geometrical Data
Functional Data

Manufacturing Featureswith the Proper
Manufacturing Information
to Generate the Shapes

Fig.2 Geometrical data and functional data for the
automatic extraction of manufacturing features with theirproper manufacturing information
3.

THE STRUCTURE OF THE FEATURELIBRARY
As mentioned in the previous section, for the
automatic extraction of manufacturing information tocreate the shape of the manufacturing features, it isimportant to understand the designer’s intention, which isrepresented by the functions of the face elements that
construct the features. For the development of the featurelibrary, the use of function feature ontology is proposed. A
function feature is defined here as a geometric shape andits functions as intended by the designer.
Fig. 3 shows the ontology of function features, themanufacturing feature ontology, and the relation between
the two ontologies.
For the creation of the function feature ontology,
first, features such as thru-slot, step etc are listed up. This
research uses the list of features proposed in (Butterfield
et al 1988). Then sub-classes of these features are createdby describing the required function of the face elementsthat construct the features.
For the creation of the manufacturing feature
ontology, first, manufacturing features such as thru-slot,
step etc are listed up. Sub-classes of these manufacturingfeatures are created by describing the generalmanufacturing methods to create the parent classes.
Sub-classes of these sub-classes are created by describing
the more specific manufacturing methods to create the
manufacturing feature. For example, a round thru holefeature can be manufactured by drilling, milling etc. So,
the sub-classes of the round thru-hole feature will be“milled thru-hole” feature class, “drilled thru-hole”
feature class etc. The sub-classes of the “drilled thru-hole”
feature class will be “threaded drilled thru-hole” feature,“precise drilled thru-hole” feature etc.
The relation between the classes in the lowest levelof the manufacturing feature ontology and the function
feature ontology represents how the manufacturingfeatures should be manufactured to fulfill the required
functions of the face elements that construct the
manufacturing features. For example, a “threaded drilledthru-hole” class of the manufacturing feature ontology canhave a relation with the “round thru-hole with both faceelements
require:Basicfunction:
fixation.
Mechanism:bolt-only. Motion: stationary-object” class ofthe function feature ontology, since threading is the
manufacturing method used to create the round thru-holewith the intended functions.
Instances of the classes in the lowest level of the
manufacturing feature ontology should also be created,
where each instances should have its own uniquemanufacturing information. The creation of the instancesof the manufacturing feature classes can be done byconsidering the specific size of the manufacturingfeatures.
By developing a feature library based on the
proposed structure, the feature library can be useful forthe automatic extraction of manufacturing features with
their proper manufacturing information. For example,
when a round thru-hole feature is extracted by a feature
recognition method, and the functional properties of theface elements that construct the round thru-hole featurelead to the extraction of the “threaded drilled thru-hole”
feature class, a proper manufacturing information can beextracted automatically from the instance of the
manufacturing feature class.
The automatic extraction of manufacturing featureswith their proper manufacturing information is aManufacturing
Feature Ontology

Function Feature
Ontology
Function Features

Manufacturing Featuressub-classStep

sub-classRound Thru-Holesub-classRound thru-hole with both
face elements require:
Basic Function : Constraint
Mechanism : Rigidity
Motion : Weak Radial

Round Thru-Hole

Step

Stepped-HoleStepped-Holesub-classRound thru-hole with both
face elements require:
Basic Function : fixation
Mechanism : Bolt-only
Motion : Stationary-object

relation

MilledThru-Hole

DrilledThru-Holesub-class

Threaded
DrilledThru-Hole

PreciseDrilledThru-Holeinstance

instance
Threaded Drilled
Thru-Hole1
Manufacturing
Information:
machine, tool, etc

Threaded Drilled
Thru-Hole2
Manufacturing
Information:
machine, tool, etc

Fig.3 The structure of the feature librarysignificant step for the realization of the automatic
generation of process plans.
4.

THE WIKI-BASED FEATURE LIBRARY

4.1 SEMANTIC EXTENSION OF MEDIAWIKIMediaWiki is a Wiki software that is written in PHP
and uses MySQL database. It is being used to run the
Wikipedia and also other web-based encyclopedias anddictionaries. MediaWiki is a very useful tool for thecollaborative content management.
An extension of MediaWiki to enable the writing of
the labeled link has been proposed in other report(Muljadi et al 2005). This extension has enabled the Wiki
to write Resource Description Framework (RDF)
statement, which consists of subject-predicate-object
triple. RDF is a language to express metadata about
information resource on the Web proposed by the WWW
Consortium (W3C) (Miller et al 2004). RDF has a simple
data model that is understandable by human and is easy
for computer applications to process and manipulate.
The Wiki syntax to write the RDF triple is [[Term:target_page|property]]. The RDF triple is <source_page><property> <target_page>. Each time the Wiki syntax isused, the Wiki engine will store the RDF triple into a tablein the Wiki database. By directly querying the table, thelabeled link relation will be displayed as follows.
1) On the source_page: -> property -> target_page2) On the target_page: <- property <- source_page3) On the property: source_page -> target_page
Fig.4 illustrates the RDF triple construction and therelation of pages displayed on the Wiki pages in theextended MediaWiki. Fig.5 shows the overall structure of
the extended MediaWiki. The extended MediaWiki as anextension of MediaWiki has the benefit of having all thefunctions available in MediaWiki as a content
management system, and can be used as an editor of
metadata according to simple RDF statement. The RDF
triples which are stored in a table, can be exported to RDF
Database for mapping to other Semantic Web applications.
The running system of the extended MediaWiki isavailable at http://semanticwiki.jp.
The development of the Wiki-based feature libraryis based on the extended MediaWiki proposed in (Muljadi
et al 2005).
4.2 DEVELOPING A WIKI-BASED FEATURELIBRARY
For the development of the Wiki-based featurelibrary, further extension of MediaWiki is done. New
namespaces are created. Namespace (“FF:”) is created todeal with the function feature ontology, and namespace(“MF:”) for the manufacturing feature ontology. New
tables are also created in the Wiki database to deal with
the new namespaces.
For the creation of the function feature ontology,
the Wiki syntax [[FF:feature_subclass|subclass]] is used(see Fig.6). When the Wiki syntax is written on the parent
class page, the Wiki engine will store the RDF triple intoa table which deals with the namespace (“FF:”) in the
Wiki database. By directly querying the table, the labeledlink relation will be displayed as follows.
1) On the parent class page: -> subclass -> feature_subclass (see Fig.7).
2) On the feature_subclass page: <- subclass <- parent
class (see Fig.8).
3) On the subclass page: parent class -> feature_subclass(see Fig.9).

Writing the Wiki syntax[[Term: target_page|property]]
to construct RDF triple

Term:Bart
Edit Box[[Term: Homer|Father]]

The constructed RDF triple
Term:Bart

Term:Father

Term:Homer<source_page><property><target_page>

Display on the Wiki pages
Term:Father

Term:Bart-> Father -> Homer

Term:Homer<- Father <- Homer

Bart -> Homersource_page: -> property -> target_page

property: source_page -> target_page

target_page: <- property <- source_page

Fig.4 RDF triple construction and the display on the Wiki pages in the extended MediaWiki

RDF DBWeb Server(Apache 2)labeledlink
process

RDF
ImportOther
Semantic Web
Applications

RDF
ExportWiki Engine(MediaWiki 1.5.x)

MySQL
Semantic
Wiki

Table for triples

Fig. 5 Overall structuore of the extended

Fig.7 Display on the parent class pageFig. 8 Display on the feature_subclass pageFig.6 Writing the Wiki syntax[[FF:feature_subclass|subclass]]

Fig. 9 Display on the “FF:subclass” pageThe “FF:subclass” page can be used to see all theclass-sub-class relations of the function feature ontology.

Fig.10 illustrates the page relations in the
manufacturing feature ontology. For the creation ofclass-sub-class relations in the manufacturing feature
ontology, the Wiki syntax [[MF:feature_subclass|subclass]] is used. When the Wiki syntax is written on theparent class page, the Wiki engine will display the labeledlink relations in the same way as in the function feature
ontology. The “MF:subclass” page can be used to see all
the class-sub-class relations of the manufacturing feature
ontology. For the class-instance relation in the
manufacturing feature ontology, the Wiki syntax [[Term:
instance_page|property]] can be used. Feature size etc canbe used as the property. When the Wiki syntax is written
on the manufacturing_feature_class page, the Wiki engine
will display the labeled link relation as follows.
1) On the manufacturing_feature_class page: -> property-> instance_page2) On the instance page: <- property <- manufacturing_
feature_class3) On the property page: manufacturing_feature_class ->Instance_page

sub-classsub-classsub-classsub-classsub-classinstance

sub-classinstance

Fig.10 Page relations in the manufacturing feature ontology

To write the manufacturing information such asmachine types on the instance page, the Wiki syntax[[Term:machine_name|machine]] is used. Fig.11 andFig.12 show the Wiki syntax writing and the display on
the instance page respectively.
To make the relation between the lowest sub-classof the function feature ontology and the lowest sub-classof the manufacturing feature ontology, the Wiki syntax[[MF:manufacturing_feature_class|related]]
isused.
Fig.13 shows the Wiki syntax writing on thefunction_feature_class page. When the Wiki syntax iswritten on the function_feature_class page, the Wiki
engine will display the labeled link relation as follows.
1) On the function_feature_class page: -> related ->manufacturing_feature_class (see Fig.14)
2) On the manufacturing_feature_class page: <- related<- function_feature_class (see Fig.15)
3) On the related page: function_feature_class ->manufacturing_feature_class (see Fig.16)
The “MF:related” page can be used to see all the
relations between the lowest sub-class of the function
feature ontology and the lowest sub-class of the
manufacturing feature ontology.
The Wiki-based feature library is able to construct
the function feature ontology, the manufacturing feature
ontology, and the relation between the two ontologies. It
also can be used to manage the manufacturing
information to create the manufacturing feature. The
Wiki-based feature library can be easily, visibly andcollaboratively modified. And since the page relation canbe represented in an RDF triple representation, the page
relation can be processed automatically by computer
applications. Thus, the Wiki-based feature library can beused to enable the automatic extraction of manufacturingfeatures and their proper manufacturing information.

Fig.11 Writing the manufacturing information on the
instance pageFig.14 Display on the lowest sub-class of the function
feature ontology

Fig.12 The display on the instance pageFig.15 Display on the lowest sub-class of the
manufacturing feature ontology

Fig.13 Writing the Wiki syntax[[MF:manufacturing_feature_class|related]]

Fig.16 Display on the “MF:Related” page

5 CONCLUSION
This research can be summarized as follows.
1) The feature library consists of the function feature
ontology and the manufacturing feature ontology. The
relation between the classes in the lowest level of the
manufacturing feature ontology and the function
feature ontology represents how the manufacturingfeatures should be manufactured to fulfill the required
functions of the face elements that construct the
manufacturing feature. By developing the featurelibrary based on the proposed structure, the extractionof manufacturing features with their proper
manufacturing information for the generation ofprocess plans is made possible.
2) MediaWiki is modified for the development of thefeature library. The Wiki-based feature library is able
to construct the function feature ontology, themanufacturing feature ontology, and the relation
between the two ontologies. It also can be used to
manage the manufacturing information to create the
manufacturing feature. The Wiki-based feature libraryis a very simple system, and as one tries to modify thefeature library, one may enjoy the visible modificationof the feature library. And since the page relations are
written in RDF triples, the page relations can beprocessed automatically by computer applications.
Thus, the Wiki-based feature library can be used toenable the automatic extraction of manufacturingfeatures and their manufacturing information.
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