Standards Integration Using Ontologies: Application to Turning Tools

Laurent Deshayes1, IFMA, Lami, Clermont Ferrand, France

Michael GruningerDPG Group, MSID Division, National Institute of Standards and Technology2

Mail Stop 8263, 100 Bureau Drive, Gaithersburg, MD 20899, U.S.A.ldeshaye@nist.gov, gruning@nist.gov, sfoufou@nist.gov

Sebti Foufou3

LE2i Laboratory, University of Burgundy, B.P. 47870, Dijon France.sfoufou@u-bourgogne.fr

Abstract

Standards form an important aspect of manufacturing knowledge as they reflect consensus on the semantics of terms for a wide variety of industries. Standards integration concerns the explicit representation of the overlapping sets of concepts in standards and the differences in their semantics to ensure that these standards are used consistently together. Standards conformance determines whether the interpretation of the standardized terms used by software applications is consistent with semantics of the terminology used in the standards. This paper proposes a general architecture to design ontologies for checking standards integration and conformance by using standards from systems integration and manufacturing. The ontology architecture is divided in core and definitional extensions that includes the use of the Process Specification Language (PSL) standard. The manufacturing example concerning turning tools is used to illustrate the problem. Finally this paper offers some short examples of first order logic propositions that were implemented in Prolog. Queries for standards integration and standards conformance to check the consistency of a user code with the standardized information are discussed in a final section.

Keywords: Product manufacturing, turning tools, standards integration, ontologies, first order logic.

1 He is Currently guest researcher at MSID Division, NIST, Gaithersburg, MD 20899.

2 Commercial equipment and materials are identified in order to adequately specify certain procedures. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.

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Content

1 Introduction.............................................................................................................................................2 Problem of standards integration and conformance.................................................................................2.1 Need for explicit semantics for manufacturing resources...............................................................2.2 Required semantics in standards.....................................................................................................2.3 Semantic representation review......................................................................................................3 The four semantic levels for standards integration and conformance......................................................3.1 The four levels................................................................................................................................3.2 Properties required by ontologies...................................................................................................4 Example: standard conformace and integration for turning tools............................................................4.1 The four levels for cutting tool standards.......................................................................................4.2 Fundamental concepts....................................................................................................................4.3 Standards codification system, brief review...................................................................................4.4 Example of ontologies....................................................................................................................5 Conclusion...............................................................................................................................................

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IntroductionManufacturing of mechanical parts is an important element of the product life cycle whose cost can be consequent if information about the company’s manufacturing capabilities is not considered as soon as possible in the product development. The way manufacturing processes information is exchanged can also drastically affect production costs. It was shown in [2] that early design choices influence almost 70 % of the manufacturing costs. To be able to reduce such costs, companies need standardized information exchange that allows to represent manufacturing capabilities as precisely as possible. In addition, knowledge for manufacturing engineering is a very complex set of information resources that generally crosses several engineering domains of competency. For example, when someone uses a standardized code to describe a resource, the interpretation of this code depends completely on the implicit inferences made by the operator. Standards are, in some way, consensual models created to reduce as much as possible this implicit information. In manufacturing engineering, most of these standards are decades old and are mainly based on mathematical or empirical models that presume sophisticated interpretation by highly skilled people. Most of these standards include natural languages definitions and drawings illustrating the relevant information; for most experts, the lack of such pictures impedes the interpretation of the standardized information. A clear representation of implicit information in standards is intended to avoid defining and creating redundant standards and to add more expressiveness to these models in order to facilitate their use by automated information systems. This difficulty is even more widespread today due to the globalization of partners in collaborative enterprises.The ISO 10303 [3], informally known as the STandard for the Exchange of Product model data during the product life cycle, STEP [3], is certainly the most advanced standardized model designed to address interoperability in manufacturing. Although some work has been done to develop data (STEP) models for manufacturing processes [4, 5], it has been recognized that this approach is at present limited to the modeling of product structure information that is sufficiently well defined, such as geometry, dimensions and tolerances [6-8]. For this type of information, the risks of ambiguity are relatively limited. However, the integration of heterogeneous information systems that span different engineering disciplines requires a uniform representation of knowledge that is difficult to encode and implement.

As discussed in [9] the next step for system’s integration is to precisely and formally represent the semantics of data models. For example, in order to integrate two software applications, substantial difficulties can arise in translating information from one application to the other, because these applications may use different terminology and representations of the domain. Even when applications use the same terminology, they often associate different semantics with the terms. This clash over the meaning of the terms prevents the seamless exchange of information among the applications. What is needed is a way to unambiguously and explicitly specify the terminology of the applications. To address the challenges of semantic integration and reusability, various groups within industry, academia, and government have been developing sharable and reusable models known as ontologies [10-13 + OWL]. The purpose of ontologies within engineering is to make explicit, for a given domain, the knowledge contained in engineering software and in business procedures [14].

Despite being written by people with a common background, the definitions and relations within the standard have subtle inconsistencies, which are exacerbated when attempting to use data from multiple standards or to implement the standard within manufacturing software systems. Furthermore, manufacturers frequently define their own extensions to the standard in order to satisfy domain-specific needs. Ontologies can alleviate some of these difficulties in three ways. First, they provide a precise representation for standards integration with applications along the product life cycle. Second, as a consequence of standards integration, ontologies are also able to represent implicit information contained in standards, such as drawings or natural language expressions, using languages that are interpretable by computers. Finally, the precise description of the semantics of standards can form the basis of new techniques for standards conformance checking. Ontologies can also be applied to identify user defined extensions of standardized information and allow manufacturers to explicitly represent their specific interpretations or extensions.

In this paper, we discuss the problem of standard integration and conformance for manufacturing software

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applications and propose a four level architecture to solve this problem. The paper presents also a reflection on the properties required for Ontologies to efficiently solve for standards integration and conformance checking problems. Problem of standards integration and conformanceA great number of standards for manufacturing consist in a list of well defined concepts and relations used to describe a particular domain or information about the product during its manufacturing. This is intended to avoid confusion about concepts and to facilitate interoperability throughout the product life-cycle. Nevertheless much more implicit information is often necessary for manufacturing applications to achieve adequate interoperability. This implicit knowledge is generally represented by means of figures or drawings which are part of the standard, and at the software application level users need to have a deep understanding of the concepts that engineers used to design standards. In particular even when data models are used they are not enough to explicitly specify the implications induced by the semantic of the model. Such implications need more sophisticated modelling tools using logical architectures. In our study, the integration of standards is intended to be used by a class of inference problem which require the understanding of implicit knowledge involved by terminologies. The representation of implicit knowledge is also intended to facilitate a stronger standard integration into today’s Product Life-cycle Management (PLM) tools.Need for explicit semantics for manufacturing resources

Standards form an important aspect of manufacturing knowledge as they reflect consensus on the semantics of terms for a wide variety of industries, but they are often too generic to directly apply to specific engineering applications. Consequently, they typically require additional user-defined extensions to properly capture the specific engineering knowledge of a company’s institutional experience. Since such extensions are unavoidable in practice, it is necessary to provide a flexible approach that can explicitly and modularly restrict the relations and definitions of domain-specific concepts. The representation of implicit knowledge within standards addresses two industrial needs: standards integration and standards conformance.

Standards integration concerns the explicit representation of the overlapping sets of concepts in standards and the clear characterization of the differences in their semantics to ensure that these standards are used consistently together. Standards conformance determines whether the interpretation of the terminology used by software applications is consistent with semantics of the terminology used in standards. In practice both standards integration and conformance need engineering knowledge that over-crosses several manufacturing domains. Thereby, mechanisms to incorporate domain knowledge are required to answer queries in a broader manufacturing level. These mechanisms include the representation of: implicit knowledge used by standards, and the extensions defined by users of these standards.

Resources selection can considerably affect costs and part quality. Information describing manufacturing resources is well defined into a great number of standards. Since these resources are closely related to the process, describe them precisely as well as their implication according to the process in which they are used is necessary for computer aided process planning (CAPP) systems. For example, a shop operator is always looking for the best cutting tool geometry with the longest tool life, the most flexible fixturing system etc. But several thousands of tools and tooling components are available on the market such as tool supports, inserts, tool holders, and assembly components. For these resources several efforts have been done in order to unify and standardize their description. Since 1995 the ISO’s technical committee (TC) 29 (working group 34) is working on the development of the ISO 13399 [17] which defines a dictionary and data models for cutting tools. But the main difficulty of such work is to find a real consensus in knowledge representation between worldwide companies. For example, tools for performing turning operations (turning tools) present the most standardized geometries, and still present a lot of conflicts in exchanging their characteristics; this is mainly due to the fast developments done by the cutting tool industry which is much faster than the standards. This is an important issue which makes the WG 34 to redefine almost constantly their data models. In addition, most of the development of cutting tool is experience-based, i.e., based on experimental observations, and generally they are designed to solve very specific customer needs. This clearly shows that to better automate tools selection and then drastically reduce process preparation times, it is necessary to represent as precise as possible and in a computerized format some of their implicit

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knowledge.

In addition at the time of establishing manufacturing process planning [18], because of the possible introduction of a very wide range of technologies, it is not always easy for the system analyst to elaborate a process plan using the latest or more economic technology. This is the reason why an expert analyst having a big experience in shops is generally required to solve complex process problems. The use of precise definitions of standardized knowledge as well as part of specific knowledge into software application may reduce the time spent to look for the most optimum process plan and the most adequate technology, making the company more competitive. Required semantics in standards

Manufacturing processes are characterized by sophisticated domain knowledge and a large amount of heterogeneous information across organizations and even between services of a same company. In recent decades, standards have been developed for describing resources of manufacturing processes in order to facilitate their classification, to harmonize their dimensions and clearly define properties applicable to diverse manufacturing companies. More recently, these standards are also being used with information systems [17], which was not the initial objective addressed by most of manufacturing standards. This perhaps explains why it is still difficult for these codes to be completely interpretable by computers and integrated with any STEP application protocols, even though these standards facilitate codifications.

The semantic modelling in standards takes several forms, more or less interpretable by computers. The most commons are drawings, definitions or more exactly data specification, and some of them, use data structures. Drawings are certainly the most important source of implicit knowledge representation in standards. Fig. 1 shows examples of cases where adding illustrative drawings helps to clarify the standard semantics. A subset of tool style symbols, from ISO 5608 [15], is presented. The tool style is represented by a symbol and defines three characteristics of the tool: the type of cutting process that can perform a tool style, the value of the cutting edge angle, and the type of shank. Thanks to the figures of column two, one can understand much more easily what the information means and can even know more about the context, or process, in which each tool style may be used or still the kind of machining features that each tool style is able to produce. For example the semantic conveys by a tool style of symbol D is that it can perform side turning kind of operations whose features require an angle less than or equal to 45º. It can also be used to perform chamfers whose generally require an angle of 45°. Zhao [19] showed how such knowledge is important for CAD systems to predict feasibility of design solutions. The use of this information in CAD system can, in addition, be more closely integrated with CAPP systems. See ISO 14649-12?

This is the reason why more recent standards oriented their definitions using data structure tools such as EXPRESS language, or even the XML markup. Fig. 2 shows a data structure modelled in EXPRESS-G for turning tools and extracted from the ISO/CD 14649-121 [ ]. One will notice that relations between concepts are much well defined and more interpretable by computers. Notice also that most of the concepts are optional data within the domain of computerized numerical controllers, i.e., only the cutting_edge_location is absolutely required. Within other domains, such as cutting process modelling, all others geometrical aspects of the cutting tool are required. Of course the context has to be required when information models are built. But if the context, or better said the implications of a terminology used within a context, is not well defined, sharability and integrability of standards are more difficult and often leads to information duplication. This makes the information more difficult to extract. For example code 1 and code 2 in figure 1 are codes defined within the ISO 5608 and ISO 1832 respectively. As shown in. each code contains the cutting tool dimensions information such as specified in Fig. 2. As a result, no correspondence is done between the code and the dimension's entities of the model presented in figure 2. More, the implicit semantic we outlined before, in Fig. 1 is now represented by two entities: the end_cutting_edge_angle and the side_cutting_edge_angle that are defined in the same standards, while the ISO 3002 will define them respectively as the working cutting edge angle and the working minor cutting edge angle. This was done in order to define better the positioning of the cutting edges and their angle values. Nevertheless terms used in ISO 14649 and ISO 3002 presents slightly different implications difficult to represent even for the expert. Therefore more expressiveness is required to avoid redundant information across manufacturing domains and make explicit ,very subtle, relations between concepts.

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To bring more structure to such information chaos, Semantic Web [] made is apparition into manufacturing applications. XML is the cornerstone of the semantic web, and so far, more recently developed standards begin to specify data using XML specification. This is the case of the ASME B5.59 that provides specification for data require by machine tool performance tests. Here is one example of an XML representation of some information of a machine tool performance test:

<TEST><ID>BB0676</ID><TEST_CLASS>CIRCULAR</TEST_CLASS><DATE>06-25-2005</DATE><TIME>15:05:00</TIME><DURATION>200</DURATION><MACHINE>

<ID>TurningCenterB123</ID><MANUFACTURER>Truchot</MANUFACTURER><MODEL>ATC</MODEL><SERIAL_NUMBER>SP129PTRG</SERIAL_NUMBER>

</MACHINE>....<STANDARD>ASME

<NUMBER>B5.59</NUMBER><YEAR>2005</YEAR>

</STANDARD>...

</TEST>

In this part of the ASME B5.59 XML structure, the TEST is clearly identified by its ID, TEST_CLASS, DATE, TIME, DURATION, MACHINE and STANDARD. It gives more semantic to the data collected for machine tool performance tests. Nevertheless, for the manufacturing engineer, more specified semantic is required to have a clear, unambiguous understanding of each "Tag". For example, what represents the TIME tag? Is it the time for my entire test, including tooling preparation or not? More, if we look up into the MACHINE description, the tag MODEL is used, then a researcher developing machine tool models could conclude that this tag describe a mechanistic model that is used to model the machine tool behaviour… Of course it was the machine tool model we specified! To make such distinction, natural language tables defining for each tags are still required such as (from ANSI B5.59):

MODEL : the machine model

ID: A site-specific unique alphanumeric designation for the machine. The ID can be used to point to information equivalent to other elements in <MACHINE>. To enable a unique identification of the tested machine, either <ID> must be specified or <MANUFACTURER>, <MODEL> and <SERIAL_NUMBER>.

TIME: local time at the start of the test

…More, some of the definitions require examples using pictures to make more understandable the concepts, See ASME B5.59 p59-76. Above definitions facilitate better understanding of the XML meta data (the Tags), but still provide an informal description of the semantic. In addition implications made by the ID tag require concepts from several manufacturing domains that make the modelling much difficult. When an expert from that domain is used to such information, everything is clear. But when automatic software agents try to extract the information from files obtained on a network, then confusions may be important. For example the concept "TIME" may have two different strong implications for machining scientist when used in the contexts of B5.59 standard and ISO 14649 (See Fig. 2). The time specified in figure 2

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represents the duration that a tool can perform a cut. Good! And the TIME specified in the ASME B5.59 specified the time at which a test begun … Fortunately, the context, ASME B5.59, is specified in its standard. The advantage is that this information can be presented to the user and conflict may be identified. In that sense the XML structure helps better to share in integrate standards. But it is not enough.

In other words: the basic stones are here to well define manufacturing data. But still people need to make the extra effort to structure better this information. Even if existing tools developed by the Semantic Web community may solve some of the chaos in manufacturing information sharing in the web, engineering application needs are quiet different since they need to have a clear formalism of the most subtle piece of knowledge. In other words it implies to go into more details than offers today's Semantic Web tools. Here we do not propose a complete solution of this problem. We propose to contribute by adding more structure to modelling manufacturing information. In future such structure may be part of a Manufacturing Semantic Web.

Semantic representation reviewOntologies are one way, extensively used recently, to represent semantics and implicit knowledge. Although there is a wide variety of ontologies, all approaches agree that there are two essential components of any ontology: 1) a vocabulary of terms that refer to the things (or concepts) of interest in a given domain; 2) some specification of meaning for the terms, grounded in some form of logic. What distinguishes the different approaches to ontologies is the degree and manner of specifying the necessary relationships among terms. An ontology allows representing a very rich variety of structural and non-structural relations such as generalization, inheritance, aggregation and the instantiation. It can supply a precise model for software applications. Ontologies are generally represented by using a wide variety of legible and understandable logical languages which are understandable both by human beings and machines [20]. Propositional logic is one way to model ontologies, but it lacks the expressive power to model concisely an environment with many objects and facts. First Order Logic (FOL) has much more expressivity and can represent much more complex relations between objects [ ]. The Ontology Web Language (OWL) is the language widely used by the semantic web community. In comparison to FOL, OWL is weightier and based on a taxonomic model [www.w3.org/2004/owl]. In this paper, we specify the ontologies using FOL, specifically the Knowledge Interchange Format [12, 21], which has been designed to support the interchange of knowledge among heterogeneous computer systems. Ontologies support interoperability by enabling the specification of semantics-preserving mappings between the terminologies of different applications that express the meaning of a term of one application in terms of the other application. Such mapping rules may simply link one term to another or may specify a complex transformation. A prime example of the use of a formal ontology to support semantic integration is the Process Specification Language [11, 22], which has been designed to facilitate correct and complete exchange of process information among manufacturing and business software systems (such as scheduling, process modeling, process planning, production planning, simulation, project management, workflow, and business process reengineering). The ontologies developed in the paper are consistent with extensions of PSL and some of them are even intended to be part of PSL extensions. Recent works intended to use PSL core, and definitional extensions for cutting processes modeling [23]. It also illustrates how PSL can be extended to particular manufacturing domains. This paper illustrates one of the approaches that can be used in that direction.

Because standards' development takes times, sometimes decades long, new information tools need to be incorporated that would avoid redundant standards by providing accurate and well defined formats understandable by both machines and humans.

The four semantic levels for standards integration and conformance

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Such as indicated in recent publications [31], product modelling architecture require ontology and interoperability standards in order to provide better functionality to PLM systems that are more and more developed by todays commercial applications. In [3] it was shown that in a close future better ontology architecture will be required. But, as many information technology modelling approaches of complex systems, a decomposition of the problem needs to be done. Here in place of developing a "big soup" of ontologies, it is proposed to provide a structured ontology. This is much preferable to solve our problem, i.e., standards integration and conformance for manufacturing resources and processes that may involve the definition and use of important number of concepts. Such as indicted in Figure 2, this manufacturing ontology architecture is divided into four main levels. Each level may have modules to decompose in more details the ontologies. All these modules are strongly interconnected with the product information architecture by being compliant to their standards. These four levels ontology framework is presented in this paper and illustrated in the next section through an example concerning the use of standards for turning tools codification system.

The four levels for manufacturing resources and process ontologyThe simplest way of designing ontologies would be to consider all terminologies within a unique layer and establish axioms to constraint the interpretation and implications involved by each concept. Experiences in designing knowledge bases for manufacturing systems [] shown that this approach is generally valid for a particular manufacturing problem. But, to be viable, each process needs to be re-implemented. At the time of generalizing a knowledge base modelling approach, complexity in solving a particular problem would reach in high complexities that are well known to be difficult to solve. (L.D. comment: here I have some references that I would like to use) In addition, as shown in [30], computing times for logic based reasoning systems is almost 10 times bigger than classical approaches. Such difficulties are explained by the important amount of overlapping manufacturing domains when terminologies are used to express knowledge [L.D.: Examplify]. In addition with the latest advances of product lifecycle management tools [Use S. Ray, Ram and Rachuri references], terminologies need to be formally represented in order to support reusability and sharability across information systems. Such as done by many standards committees for data exchange and sharing one way of reaching such goal is to build a modular architecture to:

• reduce the size of the problem,• be able to add additional extensions in future development, this is the approached used by STEP, but

also by PSL and demonstrated in [L.D. IJPD];• reduce overlapping concepts by using shared terminologies, that may be standardized;• facilitate queries that are emanating from different standards;• determine need for new standards.

Figure 2 shows the four ontology levels, for manufacturing resources ontologies, we propose to consider for standards integration and conformance. The four levels are presented in the following paragraphs.Vendors ontology are terms developed and used by business applications or manufacturing resources providers. These terms are generally very specific to the kind of business they are doing. It is often the case that new terminologies are created by private companies and "sold" with their products, such as the concept of COM, developed by Microsoft and largely used in the visual basic programming community. Standards ontology are created by a consortium of companies that sell or develop very similar products and need to standardize their application in order: to sell uniformed interfaces, have international references for their products. Since a consortium of companies is developing those standards, terms and concepts are generally defined differently to the vendor level. Nevertheless they are the first manufacturing level presenting some "common" agreement on the usage, definition or interpretation of terms or manufacturing systems.Domains ontology are important as a support to check consistency between standards terminologies but also to provide tools to understand the implications made by standard's terminologies used in other standards. Sometimes, even if terms used in different standards are closely related, subtil implications can make difficult for the terminology to be reusable and interpretable.Core ontology are the most generic concepts that crosses domains. PSL extensions are example of core ontology. The frontier between these two last levels is not always easy to determine. Generally core 8

ontology are reached after long tests on the domain ontologies. This level, because of its genericity across manufacturing domains, is the most suitable for full sharability and reusability of manufacturing concepts.

Notice that at the time of designing those ontologies, the 4 levels need to be considered iteratively over time. In addition, each level may use some of the concepts developed in standards for product information modelling. Those standards may be extended in order to better conform manufacturing ontology to product modelling, or vice-versa. Such conformance is crucial to integrate these ontology along the product life cycle through PLM tools.

Properties required by ontologiesDiscussion: properties that may have ontologies for standard integration and conformanceBased on our example and previous analysis discuss that ontologies may be able to:

• support inferences the ontological layers, from vendor to core ontologies.• Be interpretable by computer based systems to make easier sharability and reusability over time;• Be organized in modules, so that additional extensions can be added without altering the existing

ontologies;• Be easily interpretable by human beings through iterative interfaces to facilitate implementations and

axioms capitalization (storage)

Example: standard conformace and integration for turning tools

The four levels for cutting tool standards

Fundamental conceptsTurning tools are defined as non-rotating (or stationary) cutting tools which hold (carry) the cutting edges. They are commonly used for external machining on turning centres, but may also be used for internal machining. Characteristics of cutting tools have been relatively well standardized. This study focuses only on insertable turning tools, although the approach can be generalized to other classes of resources. As shown in Fig. 2, an insertable turning tool is a turning tool in which the cutting edge is an interchangeable insert. It is generally composed of two parts (see Fig. 2a): the tool body head, which holds the insert, and the tool body shank, which mounts the turning tool to the tool block. Therefore a turning tool supports two kinds of components:

• The cutting insert that is an interchangeable cutting edge for a cutting tool. Within this context the insert is considered alone, as an individual component. Generally a cutting insert can be moved to another position in order to use another cutting edge. Therefore, a cutting insert can hold several cutting edges. The number of cutting edges available on a cutting insert mainly depends on its geometry. The insert is also referred to as the cutting component of indexable turning tools. In the case of the inserts shown in Fig. 2b, two cutting edges are available on the insert cutting face.

• Components used to assemble the insert on the tool holder, see Fig. 2b, 2c and 2d. A clamping system inside the insert hole also fixes the insert. A combination of hole and top clamping systems fixes more strongly the insert onto the tool holder. This requirement depends on the kind of process in which the tool is being used.

Although a turning tool can be a very complex assembly product, its global geometry has to be carefully described. For example, the turning tool geometry is used in CAM to automatically select cutting tools and produce the numerical program for the machine tool. In other terms, turning tool selection is based on the geometry to be manufactured. The concepts for turning tool geometry used in this paper are represented in Fig. 3 and have been selected from the standard ISO 3002-1 [24]. These concepts are: the turning tool 9

holders whose codification is defined in ISO 5608 [15]; the indexable insert whose codification is defined in ISO 1832 [16]; the tool cutting edge is the bold dark edge and performs the cut, i.e., a part of this edge is in contact with the material; the minor cutting edge which does not perform any cut and does not have to be in contact with any material; the tool cutting edge angle, denoted by tcea, is the angle between the assumed direction of feed motion4 (or tool motion) and the tool cutting edge; the tool included angle, denoted by ia, is the angle between the cutting edge and the minor cutting edge; and, the tool minor cutting edge angle, denoted by tmcea, is the angle between the assumed direction of feed motion and the minor cutting edge5. Standards codification system, brief reviewThe two standards considered in this study, ISO 5608 [15] and ISO 1832 [16], define codes for the turning tool holder and insert respectively. The role of these codes is to classify those resources, and to represent concisely the properties of tool holders and inserts. Figure 4 shows an example of three codes, one for inserts and two for tool holder. The insert code and the first tool holder code are based on their respective standards, while the second tool holder code is a code given by a tool provider catalogue. The standardized codes are defined according to the syntax recommended by the standards: each ISO code is composed of compulsory and optional symbols. For inserts, compulsory symbols are the first height symbols and for tool holders the first nine ones. For the entire code to be valid (conform to the standard), its symbols have to be placed following a specific order and respecting a precise syntax. Each symbol represents particular properties of the resource. For example, the second symbol of the tool holder code, Fig. 4, means that the cutting edge is oriented at 90° according to the assumed direction of feed motion. This code also means that only end cutting operations can be made with such a tool holder. Tool holder properties concern tool dimensions, tolerances, and the insert’s holding methods. For inserts, symbols generally represent dimensions such as nose radius, cutting edge length, tolerances, insert shape, and included angles. These codes are detailed in ISO standards [14, 15], in specialized handbooks [25], and tool manufacturer catalogues.A turning tool is the assembly of a tool holder and an insert which are the crucial components to select since the cutting tool geometry, which will perform the work, depends on this assembly. Mounting relations (whether a given insert can be mounted on a given tool holder) can be easily verified using the ISO. For example the tool holder identified by the code in Fig. 4 is mountable with inserts because its symbols C, N, 16 and R (optional) correspond respectively to the same symbols in the code identifying the insert (dark symbols). Such relations can be easily modelled using constraints in database systems, as it is done with existing cutting tools databases. Nevertheless, information such as the possible cutting processes that can be done with a particular cutting tool and even its exact geometry is not explicitly represented.The selection of tool holder and insert does not determine whether or not the tool holder code conforms to the standard ISO 5608; furthermore, it does not allow the automatic selection of cutting tools based on part geometry analysis in CAM or CAPP environments. For example the problem of standard conformance is represented in Fig. 4 with the tool holder code provided by a tool manufacturer. For practical reasons, the place for some symbols has been changed and even some of them have additional meanings according to the standard’s description. The five compulsory symbols conform to the ISO 5608, while the next ones are user defined symbols. Such differences cannot be fully represented in actual system without costly modelling approaches. Ontologies are able to identify such differences, by checking if the code conforms to the standard, and by considering the tool provider semantic in the code in order to better automate previous manufacturing stages.Example of ontologiesShow some of the ontologies, and what are the inferences that can be done with such ontologiesm and that cannot be done with more classical approaches (OWL. Data base, XML…)

4 In turning operations, the feed motion is the motion of the tool according to the part and is generally expressed in mm/rev

5 Notice that tcea and tmcea are defined according to the turning tool space which is the space used in practice for manufacturing parts.

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ConclusionIntegration and conformance are two necessary components for the correct application of standards. In manufacturing, standards represent the consensual concept definitions within a particular domain; consequently specific knowledge proper to some organizations is not represented. This may lead to semantic conflicts in the application of the standards extensions to the standard to satisfy their particular engineering needs. The next generation of integrated systems will need a more rigorous foundation of semantics than is currently provided by data models and architectures. The approach used in this paper has demonstrated how such a first-order logic representation can be used to provide such a foundation for the semantics of terminology in standards for cutting tools.

References[1] Merchant, E., 2003, "Twentieth Century evolution of machining in the United States – an interpretative review," Sadhana, 28, Part 5, pp. 867-874.[2] Boothroyd, G., Dewhurst, P., and Knight, W., 1994, Product design for manufacturing and assembly, Second edition, New York: M. Dekker, p. 698.[3] ISO 10303-1:1994, Industrial automation systems and integration Product data representation and exchange Part 1: Overview and fundamental principles. [54] Description methods: architecture and development methodology reference manual.[4] Deshayes L., Dartigues C., Ghodous P. & Rigal J.F. 2003, Distributed and standard system for cutting data management. CERA journal, 11/1:27-36.[5] Wolff, V.; Rigal, J.-F; Ghodous, P.; Martinez, M., 2001, "Design and Machining data integration. International conference on emerging technologies and factory automation," IEEE, pp. 483 – 491.[6] ISO 10303-203, 1994, Product Data Representation and exchange – AP 203 : Configuration controlled design, International Organization for Standardization.[7] ISO 10303-214, 2001, Industrial automation systems and integration – Product data representation and exchange – Part 214: Application protocol: Automotive mechanical design process. International Organization for Standardization, Geneva.[8] ISO 10303-224, 2001, Industrial automation systems and integration – Product data representation and exchange – Part 224: Application protocol: Mechanical product definition for process planning using machining feature. International Organization for Standardization, Geneva.[3] Ray, S., 2002, “Interoperability standards in the semantic web”, Journal of Computing and Information Science in Engineering, ASME, 2, pp. 65-69. [10] Gruber, T. R., 1993, "Towards principles for the design of ontologies used for knowledge sharing," International workshop on Formal Ontology, Padova, Italy.[11] Gruninger, M. and Menzel, C., 2003, "Process Specification Language: Principlesand Applications," AI Magazine, 24:63-74.[12] Menzel, C., Hayes, P., 2003, "SCL: A Logic Standard for Semantic Integration,"Semantic Integration Workshop, Second International Semantic Web Conference,Sanibel Island.[13] Ciocoiu, M., Gruninger M., and Nau, D., 2001, "Ontologies for integrating engineering applications," Journal of Computing and Information Science in Engineering, 1, pp. 45-60.[14] Uschold, M., Gruninger, M., 1996, "Ontologies: Principles, Methods, and Applications. Knowledge Engineering Review," 11, pp. 96-137.[15] ISO 5608, Turning and copying tool holders and cartridges for indexable inserts – Designation, ISO 5608, 1995, p. 14[16] ISO 1832, Indexable Inserts for cutting tools – Designation, ISO, 1832 Geneva, 1991, 18 p.[17] ISO 13399, 2004, Cutting tool data representation and exchange – ISO 13399, Geneva.[18] Marchand F., 2000, An integrated information model for process manufacturing files (Un modèle d'information intégré pour les dossiers de fabrication), PhD thesis dissertation, Ecole Centrale de Paris,

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195 p. [19] Zhao, Y., Ridgway, K., Al-Ahmari, A. M. A, 2002, “Integration of CAD and a cutting tool selection system,” Computers & industrial Engineering, 42, pp. 17-34[20] Russel S., Norvig P., 2003, Artificial Intelligence A Modern Approach, second edition, ISBN 0-13-790395-2, 1080 p., pp.194 - 319[21] Genesereth, M.R., Fikes, R. E., 1992, Knowledge Interchange Format, Version 3.0, Reference Manual, Logic Group Report Logic-92-1, Computer Science Department, Stanford University, Stanford, California[22] Gruninger, M. and Kopena, J. (2005) Semantic Integration through Invariants,to appear in AI Magazine[23] Deshayes L., El Beqqali, O., Bouras, A., 2004, "The use of Process Specification Language for cutting processes," Accepted for publication in the International Journal of Product Develoment (IJPD).[24] ISO 3200, Basic quantities in cutting and grinding – part 1 : Geometry of the active part of cutting tools – General terms, reference systems, tool and working angles, chip breakers, ISO 3200/1, 1982, 52 p.[25] Nelson, D. H, Schneider, G. Jr, 2001, Applied manufacturing process planning : with emphasis on metal forming and machining, Prentice Hall, 720 p.[26] F. Noël, D. Brissaud, and S. Tichkiewitch, 2003, "Integrative design environment to improve collaboration between various experts," Annals of the CIRP, 52,, N. 1, pp. 109-112.[27] Urban, S., D., Rangan, R., 2004, "From Engineering Information Management (EIM) to Product Lifecycle Management (PLM)," Journal of Computing and Information Science in Engineering, 4, pp. 279-280.[28] Goble, Lou, The Blackwell guide to philosphical logic, Blackwell publisher, 2001, 510 p.[29] Deshayes, L., Welsch, L., & al, 2005, “Smart Machining Systems: Issues and Research Trends”, accepted for publication in proceedings of the 12th CIRP life cycle engineering seminar, Grenoble, France, 3-5 Avril 2005 [30] Kusak, A., Intelligent Manufacturing Systems, Prentice Hall, ISBN 0-13-468364-1, pp. 61-65.[31] S. J. Fenves, R. Sudarsan, E.R. Sriram and F. Wang, "A Product Information Modelling Framework for Product Lifecycle Management", IJPLM, …

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LIST OF FIGURES AND FIGURES

Fig. 1: The semantic conveyed by drawings for tool style defined in [15]Fig. 2: An example of insertable turning tool

Fig. 3: Characteristics of turning tool geometry [16]

Fig. 4: Standardized insert and tool holder codes as well as differences with an industrial tool holder code

Fig. 5: Ontology architecture

Fig. 6: Design constraint and dimensions (in mm) of the mechanical part

Fig. 7: Characteristics of the turning operation for machining surfaces E and F

Fig. 8: Primitive axioms for turning tool ontology

Fig. 9: Definitions for ISO 1832 ontology

Fig. 10: Definitions for ISO 5608 ontology

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Tool style symbol

Drawing Process type Cutting edge angle

Shank type

D side cutting 45o Straight shank

F end cutting 90 offset shank

G side cutting 90o Offset shank

Fig. 1: The semantic conveyed by drawings for tool style defined in [15]

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Fig. 2: A cutting tool model in EXPRESS-G from ISO 14649-121 [ ]

15

Fig. 2 The four semantic layers for manufacturing standards integration and conformance

16

Fig. 2: An example of insertable turning tool

17

Fig. 3: Characteristics of turning tool geometry [16]

Cutting edge

Minor cutting edge

Assumed direction of feed motion

Tool holder

Indexable Insert

ia tcea tmcea

Cutting face

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Fig. 4: Standardized insert and tool holder codes as well as differences with an industrial tool holder’s code

19

Fig. 5: Ontology architecture

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Fig. 7: Characteristics of the turning operation for machining surfaces E and Fb) Turning tool path and constraint on turning tool angles due to the machining feature

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An insertable turning tool is the assembly (mounting) of an indexable insert and of a tool holder (forall (?x ?y) (implies (turningTool ?x ?y ) ( and (toolHolder ?x)

(insert ?y ) (mounting ?x ?y)))) The tool cutting edge angle, tcea, is the angle included between the cutting tool edge and the feed rate direction.

(forall (?x

?y ?w ) (iff (tcea ?x ?y ?w) (exists (?v ?z) (and (turningTool ?x ?y)

(cuttingEdge ?x ?y ?z) (feedDirection ?x ?y ?v) (angleBetween ?z ?v ?w))))

) The included angle is the angle included between the cutting tool edge and the secondary tool edge.

(forall (?x ?y ?w) (iff (ia ?x ?y ?w) (exists ?z ?v) (and (turningTool ?x ?y) (cuttingEdge ?x ?y ?z)

(minorCuttingEdge ?x ?y ?v) (angleBetween ?v ?z ?w))))) The tool minor cutting edge angle, tmca,

is the angle included between the secondary cutting tool edge and the feed rate direction. (forall (?x ?v ?y) (iff (tmcea ?x ?y ?v) (exists (?w ?z)

(

and (turningTool ?x ?y ) (minorCuttingEdge ?x ?y ?w) (feedDirection ?x ?y ?z)

(angleBetween ?z ?w ?v)))))

The first symbol of the insert code defined in the standard ISO 1832 is the insert shape. (forall (?x ?y) (implies (ISO_1832_1 ?x ?y) (and (insertShape ?x ?y)

(insert ?x)

))) An insert shape is a property of an insert and includes the information about the number of cutting edges, included angle, and description shape. (forall (?x ?y) (implies (ISO_1832_1 ?x ?y)

(exi

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(1)(2)

(3)(4)

Fig. 8: Primitive axioms for turning tool ontology(5)(6)(7)(8)

Fig. 9: Definitions for ISO 1832 ontologysts (?u ?v ?w) (and (numberCuttingEdges ?x ?u) (insert_ia

?x ?v) (descriptionShape ?x ?w))))) For all insert ?x, the insert includ

ed angle can be 80 if the insert shape of ?x is C, or 55 if the insert shape of ?x, or… (forall (?x ?y) (implies (ISO_1832_1 ?x ?y) (or (and (Insert_ia ?x 80)(InsertShape ?x C))

(and (Insert

_ia ?x 55)(InsertShape ?x D)) (and (Insert_ia ?x 75)(InsertShape ?x E)) (and (Insert_ia ?x 120)(InsertShape ?x H))))) An insert code has a first symbol of value C if and only if,

according to the

standard ISO 1832, the number of cutting edges is two, the included angle value is 80° and if the insert shape is rhombic. (forall (?x ?y) (iff (ISO_1832_1 ?x C)

(and (numberCuttingEdge ?x 2) (insert_ia ?x 80) (descriptionShape ?x rhombic))))

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The third symbol of the tool holder code defined in the standard ISO 5608 is the tool style. (forall (?x ?y) (implies (ISO_5608_3 ?x ?y) (and (toolStyle ?x ?y)

(toolHolder ?x)))) Tool style is a property of a tool holder and includes the information about the tool cutting edge angle, shank type and cutting processes which can be performed with the tool style.

(forall (?w) (implies (ISO_5608_3 ?x ?y)

(exists ( ?u ?v ?w) (and (toolHolder_tcea ?x ?u) (shankType ?x ?v) (cuttingProcess ?x ?w)))))

For all tool holder code ?x the third symbol ?y for tool holder implies that the tool holder requires to perform a side cutting activity or a end cutting activity or both. (forall (?x ?y)

(implies (ISO_5608_3 ?x ?y)

(or (requires sideCutting ?x) (requires endCutting ?x) (and (requires sideCutting ?x)

(requires endCutting ?x))))) A tool holder code has a third symbol of value A implies that, according to the standard ISO 5608, the cutting edge angle value is 90°, the shank type is straight, and

that the SideCutting operation re

quires this code. (forall (?x ?y) (implies (ISO_5608_3 ?x A) (and (toolHolder_tcea ?x 90)

(shankType ?x straight) (requires sideCutting ?x))))

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(9)(10)(11)(12)

Fig. 10: Definitions for ISO 5608 ontology

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