Manufacturing Feature Library as a Manufacturing Information
Management System for Process Planning¹Hendry MULJADI, ²Keiichi KITAJIMA, ¹Hideaki TAKEDA, ²Koichi ANDO
¹National Institute of Informatics, ²Shibaura Institute of Technology¹2-1-2, Hitotsubashi, Chiyoda-ku, Tokyo, Japan, ²3-7-5, Toyosu, Koto-ku, Tokyo, Japan
hendry@nii.ac.jp
Abstract
A manufacturing feature can be defined simply as a geometric shape and its manufacturing
information to create the shape. For the generation of process plans in a manufacturing feature-based
process planning system, it is necessary to develop a manufacturing feature library that consists of predefined manufacturing features and the manufacturing information to create the shape of the features.
In other words, manufacturing feature library plays an important role for the extraction of
manufacturing features with their proper manufacturing information. However, to manage the
manufacturing information flexibly, it is important to build a manufacturing feature library that is easy
to manage. In this paper, the implementation of Semantic Wiki for the development of the
manufacturing feature library as the manufacturing information management system is proposed.

KEY WORDS : manufacturing feature, manufacturing feature ontology, feature library,process planning, Wiki, Semantic Wiki, RDF
1Introduction

Process planning plays an important role in the manufacturing cycle as it determines how a product is
to be manufactured. It is also important to emphasize that almost any industrial inquiry concerning the
manufacturing process such as floor space, due dates, lead time, work in process etc, addresses processplanning as a data source (Halevi, 2003). However, manual process planning is time consuming, labor
intensive and may involve human errors (Elmaraghy, 1993). In order to solve these problems,Computer Aided Process Planning (CAPP) as a means to support humans effectively to generate
process plans has been a research topic for over 35 years (Luttervelt, 2003).
In the context of CAPP system development, feature technology has emerged as the enabling
technology to convert CAD product data to manufacturing information (Han & Rosen, 1998). A
manufacturing feature can be defined simply as a geometric shape and its manufacturing information
to create the shape. Many different approaches have been developed to extract features from the CAD
product data (Subrahmanyam, 2002). However, most feature recognition methods only deal with theautomatic extraction of geometric shape from the CAD product data.
For the generation of process plans, it is necessary to deal with the extraction of proper manufacturing
information to create the shape. For the extraction of manufacturing features and their manufacturing
information, it is necessary to develop a manufacturing feature library that consists of pre-definedmanufacturing features and the manufacturing information to create the shape of the features(Kanamaru, Ando, Muljadi & Ogawa, 2004). The manufacturing information consists of the required
machine and tool data, the estimated cost and time data, etc (Scallan, 2004). However, managing
manufacturing information is not an easy task. A manufacturing feature library needs to be easily
modified or customized, since manufacturing technology is progressing and facilities available in anindustrial plant may not be the same as the other.

In this paper, the implementation of Semantic Wiki for the development of the manufacturing featurelibrary is proposed. The structure of this paper is as follows. Section 2 describes MewKISS, theSemantic Wiki engine used for the manufacturing feature library. Section 3 describes theimplementation of MewKISS for the development of the manufacturing feature library. Section 4states the conclusions drawn from this research.
2

MewKISS

2.1 Extending MediaWiki
MewKISS is an abbreviation for MediaWiki with Simple Semantics. The word “KISS” is written withfull capital letters to stress that the proposed Semantic Wiki is developed by following the KISS
principle that stresses simplicity. The word “KISS” is originally an abbreviation for “Keep It Simple,
Stupid!” or “Keep It Short and Simple”.
MediaWiki is the Wiki software used for the development of MewKISS. MediaWiki has the category
management function that allows a Wiki page under the namespace (“Category:”) to be used as a
metadata. Metadata is simply defined here as data about data (Takeda, 2004). This function allows
user to create class-sub-class relation and class-instance relation of Wiki pages. However, themetadata cannot be processed nor manipulated easily by computer applications.
Using the existing category management function as a reference, MediaWiki is extended. The
extension has enabled MediaWiki to write labeled links. In other words, the extension has enabledMediaWiki to write Resource Description Framework (RDF) statement, which consists of subjectpredicate-object triple. RDF is a language to express metadata about information resource on the Web
proposed by the WWW Consortium (W3C) (Miller, Swick & Brickley, 2004). RDF has a simple data
model that is understandable by human and is easy for computer applications to process andmanipulate.
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 is used, the Wiki engine willstore the RDF triple into a table in the Wiki database.
Fig.1 shows the example of the Wiki syntax writing on a Wiki page. The Wiki page on which thesyntax is written will become the source page of the RDF triple. Figure 2 illustrates an RDF triple thatis stored in the new table of the Wiki database. Figure 3(a), (b), (c) show how the labeled link relations
are displayed on the source page, target page and property page respectively. Displaying labeled link
relation allows users to navigate the relation between pages easily. And since the original MediaWiki
can be used for a collaborative content management, MewKISS can be used as a collaborative andintegrated content and metadata management system (Muljadi & Takeda, 2005).

Fig.1 Wiki syntax to write the labeled link: [[Term:target_page|property]]ChildHomer<subject>

Bart<predicate><object>

Fig.2 RDF Triple(a) Display of the source page->property page->target page(b) Display of the target page(c) Display of the property page<-property page<-source pagesource page->target pageFig.3 Display on the Wiki pages

2.2 Mapping to other Semantic Web Applications
Enabling MediaWiki to write labeled links with simple syntax allows users to create and manage
relations between Wiki pages easily and flexibly. The writing of labeled links allows users to writeand edit RDF triples even though users have no knowledge about it.
Fig.4 shows the overall structure of MewKISS. By converting the RDF triples stored in the MewKISS
database into XML-encoded RDF data format, the RDF triples can be exported to RDF database suchas Sesame. Using Sesame, users can explore the exported RDF triples (see Fig.5), make queries etc(Broekstra & Kampman, 2004). Sesame can also bridge MewKISS to other Semantic Web
applications. In other words, metadata created in MewKISS environment can be mapped to other
Semantic Web applications.

SESAMEWeb Server (Apache 2)labeledlink
process

RDF
ImportRDF
ExportWiki Engine(MediaWiki 1.5.x)

MySQL

MewKISS

Table for triples

Fig.4 The overall structure of MewKISS

Other
Semantic Web
Applications

(a)

(b)
Fig.5 Exploring the RDF repository
3

Manufacturing Feature Library

3.1 The Structure of the Manufacturing Feature Library
For the development of the manufacturing feature library, manufacturing feature ontology is created as
the structure of the library (see Fig.6). This lightweight ontology is created as follows.
(1) Level 0: Ontology name(2) Level 1: Manufacturing features such as step, slot etc are listed up. The manufacturing features
used in this research are based on the library proposed by CAM-I (Butterfield, Green, Scott &Stoker, 1988).
(3) Level 2: Sub-classes of the manufacturing features classes in level 1 are created by describing the
manufacturing methods to create the shape of the parent classes.
(4) Level 3: Sub-classes of the classes in level 2 are created by describing the tool types required forthe manufacturing method. Some feature classes in level 2 may have no sub-class.

(5) Instances of the lowest classes are created. Each instance contains specific manufacturing
information, such as machine type, tool type, machining speed.
Since manufacturing technology is progressing and facilities available in an industrial plant may differ
to other plant, the classes of the manufacturing feature ontology may need to be changed or updated.
In other words, an easy-to-modify environment is necessary to develop and manage the manufacturingfeature library.

Manufacturing Features

Level 0sub-class
Level 1sub-class

Step

Thru Slot

Open Pocket･･･

sub-classsub-classMilled Thru-Slot

Level 2sub-classsub-classElectrical Discharged Thru-Slot
sub-classsub-class
Level 3

End Milled Thru-Slotinstance

Instances

Plain Milled Thru-Slot

Side Milled Thru-Slotinstance

End Milled Thru-Slot1
Tool ：End Milling Cutter
Machine ：Machining Center

Plain Milled Thru-Slot1
Tool ：Plain Milling Cutter
Machine ：Machining Center

Fig. 6 Manufacturing feature ontology
3.2 Implementation of MewKISS
For the development of the manufacturing feature library, further extension of MewKISS is done.
Fig.7 shows the illustration of the manufacturing feature library. A new namespace (“MF:”) is created
to deal with the manufacturing feature classes. A new table is also created in the MewKISS databaseto deal with the new namespace. Each instances of the lowest class of the manufacturing feature ishandled as a page without namespace in the Wiki environment. The manufacturing information is also
handled as a Wiki page without namespace.
The Wiki syntax [[MF:feature_subclass|subclass]] is used to create class-sub-class relations of the
manufacturing feature ontology (see Fig.8). When the Wiki syntax is written on the parent class page,
MewKISS will display the labeled link relations as follows.
(1) On the parent class page: -> subclass -> feature_subclass.
(2) On the feature_subclass page: <- subclass <- parent class.
(3) On the subclass page: parent class -> feature_subclass. “MF:subclass” page can be used to checkall the class-sub-class relations existing in the manufacturing feature library (see Fig.9).
For the class-instance relation of the manufacturing feature ontology, Wiki syntax[[Term:instance_page|instance]] is used (see Fig.10). 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: -> instance -> instance_page2) On the instance page: <- instance <- manufacturing_ feature_class3) On the “instance” page: manufacturing_feature_class -> instance_page

On the instance page, relation with manufacturing information can be written using the Wiki syntax[[Term:manufacturing_information|property]] (see Fig.11). Metadata of the manufacturing
information can also be created easily using the similar Wiki syntax.
Thus, using the modified MewKISS, users can manage the relation between manufacturing featuresand manufacturing information, as well as the metadata of the manufacturing information easily.

Level 0sub-classsub-class

Level 1sub-classsub-class

Level 2sub-classsub-classsub-class

Level 3

instance
instance

instance

InstancesmachinemachineManufacturing
Information

Fig. 7 Illustration of the manufacturing feature library.

Fig.8 Writing the Wiki syntax: [[MF:feature_subclass|subclass]]

Fig.9 MF:subclass pageFig.10 Writing the Wiki syntax: [[Term:instance_page|instance]]

Fig.11 Writing the Wiki syntax: [[Term:manufacturing_information|property]]
3.3 Discussion
As shown in Section 3.2, the modified MewKISS provides an environment where users can manage
the relation between manufacturing features and manufacturing information in the manufacturingfeature library easily. The modified MewKISS also provides a collaborative environment where many
people can work together to manage the manufacturing feature library.
Displaying labeled link relation allows users to navigate the relation between pages easily. Thisnavigation support may assist users to collect manufacturing information for the generation of processplans.
And since users can write page relations in RDF triple representation, even though they have noknowledge about it, the page relation can be processed and manipulated by other Semantic Web
applications or other computer applications. In other words, by storing the metadata in RDF triples, themetadata can also be mapped easily to other applications. Further work needs to be done on how themapping to other Semantic Web applications may benefit the realization of automatic processplanning.
4

Conclusions

This paper described the implementation of Semantic Wiki for the development of manufacturingfeature library. By enabling the writing of labeled link, class-sub-class relation and the class-instance
relation of the manufacturing feature ontology, and the relation between manufacturing feature andmanufacturing information can be easily constructed in the modified MewKISS environment. And
since the page relation is written in RDF triple representation, the metadata can be mapped to otherapplications.
MewKISS provides a collaborative and easy-to-use environment for users to manage the
manufacturing feature library. User friendliness of a tool is very important to foster the participation ofskilled engineers to store their knowledge in the manufacturing feature library. Thus, themanufacturing feature library can be useful for the management of manufacturing information for thegeneration of process plans.
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