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Executive Summary

Manufacturing resources are the equipment which enable industry to turn raw materials into marketable products. Computer-interpretable representations of manufacturing resources are employed within a variety of manufacturing software applications, including software to perform manufacturing process planning, manufacturing simulation, tool selection, manufacturing cost estimation, and machine tool programming. Manufacturing enterprises often rely on multiple software systems, purchased from different vendors, each of which requires access to different representations of the manufacturing resources used by that facility. This situation results in resource data stored and maintained multiple times in multiple formats for different applications within a givenfacility. This in turn causes much duplicate work for maintaining the information, redundant data stores of manufacturing resource data which may or may not contain the most recent and accurate information, and longer lead times for implementing new systems which require this data. System integration or sharing of resource data between systems or engineering functions is not possible without information loss in the current environment.

A single representation for manufacturing resource information that is common to a variety of software applications and engineering functions would reduce or eliminate these problems. This common representation would shorten product cycle time by enabling system integration and sharing of resource data, reduce software operating costs by eliminating costly maintenance of multiple data stores, increase usability and applicability of existing corporate databases, lower manufacturing costs through less duplication of effort and more efficient engineering functions, and increase product quality by allowing ready access to the facility's most current and accurate manufacturing resource data. Common representations of manufacturing resources can also enable the manufacturing resource vendors themselves to offer documentation of their products via mechanisms consistent with state-of-the-art computing and networking technologies, including integrated databases, CD-ROM disks, on-line services, or electronic vendor updates.

This specification presents results from a focused effort to comprehensively identify the characteristics of a limited set of manufacturing resources to form the basis for a common representation. The document contains technical requirements to describe the information categories, attributes, and relationships for use in development of a common representation. The resources so characterized include milling and turning machine tools, cutting tools appropriate to the processes of milling, drilling, boring, reaming, tapping, turning, grooving, etc., and the tool assembly components required to mount the cutting tools to the machines. The methodology used to determine these characteristics is principally based on a thorough examination of manufacturing software usage of manufacturing resource data, existing manufacturing resource standards, tooling vendor representations, and related work performed in industry and academia. The resulting manufacturing resource characteristics are organized in a hierarchical fashion and include thorough descriptions of all resource attributes.

These manufacturing resource requirements are intended to serve as the starting point for a future standardized manufacturing resource representation. The authors fully expect that this initial specification will change and grow based on further review and future implementation experience. It is requested that this document be reviewed and analyzed by several different audiences from differing perspectives, including manufacturing resource vendors, manufacturing software vendors, and mechanical parts manufacturers. Future plans include widespread review of the information contained in this specification, development of a formal representation of these requirements in the form of an information model, implementation of a prototype manufacturing resource database, validation and demonstration of the proposed resource data structure, and pursuit of a standardized manufacturing resource representation.

Introduction

This effort was identified as an industry need by the Rapid Response Manufacturing (RRM) program. RRM was established in early 1992 to "provide the effort needed to effectively enable engineers to reduce the time required to design and manufacture products in response to rapidly fluctuating market demands by one-half." [7] The objective of the program is to shorten time-to-market, improve quality-to-cost, and enhance product reliability. The RRM program is performed by a consortium of companies, composed of both manufacturing facilities and software vendors, and is coordinated through the National Center for Manufacturing Sciences (NCMS). This program is sponsored through the Department of Commerce Advanced Technology Program (ATP) administered by the National Institute of Standards and Technology (NIST). Activities of the RRM consortium include developing new processes, adding new functionality to CAD/CAM/CAE software applications, and improving system and process integration among various engineering functions and software applications.

The NIST RRM Project is sponsored as an intramural project through the NIST ATP office to support the objectives of the RRM consortium. The RRM Intramural Project is managed and executed through the Manufacturing Systems Integration Division (MSID). The RRM Intramural Project supports RRM program efforts by leveraging NIST skills and technologies to ensure the advancement of RRM capabilities, collaborating to develop and adopt key technologies, and providing a standardization focus to the results of the RRM consortium. Specific activities of the RRM Intramural Project are determined by research and technology needs identified by consortium member companies.

This specification presents initial results from an RRM Intramural Project effort to develop a proposed representation of manufacturing resource data. This document contains technical requirements to describe the information categories, attributes, and relationships for use in development of a common representation. This effort was identified as a high priority research need by the RRM consortium and supports the RRM program objective by proposing a representation of manufacturing resources which may be adopted as a common basis for information exchange. This RRM Intramural Project effort (termed Phase 1 for the timeframe of FY94/95) intends to develop and validate information models for the representation of manufacturing resources, with a longer-term goal of future standardization.

Problem Statement

In the domain of mechanical design and manufacturing, information sharing between computer aided engineering (CAE) applications is typically synonymous with product design data exchange. Other information elements which are relevant to and necessary for the functions performed by CAE applications are frequently overlooked. For example, information describing machine tool capabilities is necessary for manufacturing planning and simulation purposes; information describing specific process characteristics is useful for analysis and cost estimation purposes. It is clear that CAE applications need such information, and it is equally clear that each CAE vendor maintains such information in subtly different ways. Moreover, the originating sources of such information (e.g., machine and cutting tool manufacturers) frequently do not provide equivalent characterizations of their products, thus compounding the problem.

Several efforts have been initiated within industry to develop information constructs (e.g., databases, information models) that describe manufacturing resource (MR) data. MR data may include information describing machines and other production tools, material handling equipment, cutting tools, inserts, tool holders, tool adaptors, collets, fixtures, material inventories, factory layout, and so on. The existing efforts have typically resulted in company-specific data structures and system implementations. The implementations are frequently applicable to only a single CAE application within the organization, with much duplicated effort required to implement systems for additional application areas.

Complete, validated, and publicly available information models that describe MR data could be used as the basis to codify the types, characteristics, and relationships between the MR data needed to support work performed with CAE applications. The acceptance of such MR information models could lead to more efficient implementations of CAE applications, eliminate multiple redundant stores of MR data, and allow more seamless application system integration. The development of validated MR information models could also serve as a catalyst to standardize these models in the future by providing proven results and a working strawman to appropriate standards organizations. Availability of standard MR information models would allow CAE application vendors and research organizations to concentrate on application-specific problems as opposed to acquisition, representation, and maintenance of MR data. Standard MR information models could also be used by manufacturing resource providers (e.g., machine tool vendors) to disseminate specifications for their products via mechanisms consistent with state-of-the-art computing and networking technologies, including integrated databases, CD-ROM disks, on-line services, or electronic vendor updates. Finally, standard MR information models would also facilitate the establishment of electronic MR "data books" and catalogs for use throughout the manufacturing industry.

Document Purpose

This document provides the detailed information requirements that a limited, "first-approximation" MR information model should satisfy for a given domain of machine tools, cutting tools, and tooling components. As such, it is expected that this document will be reviewed and analyzed by several different audiences from differing perspectives. CAE software vendors should consider these requirements in light of whether sufficient information is captured to support the execution of their applications. CAE software users should consider these requirements with a similar perspective to that of the vendors, but with additional consideration as to whether sufficient information is captured to support specialized applications developed "in-house", as well as whether the amount of information described could be maintained in a cost-effective manner. Manufacturing resource vendors (e.g., machine and cutting tool vendors) should consider these requirements from the standpoint of whether they would be willing to provide the information specified for their products. Finally, since this project intends to use these requirements as the primary basis for the development of an EXPRESS ¹ data specification, those readers knowledgeable in information modeling practice should consider whether there is sufficient detail in the requirements to develop a complete model.

The content of this document is structured as follows. The Technical Discussion section describes the resource data scope addressed by this project and the specific methodology and sources used for obtaining and analyzing the raw data during development of the MR data requirements. The Documentation Method for MR Requirements section describes the structure of the resource data tables, provides examples to illustrate how the requirements are documented, and defines the terminology and conventions used throughout the tables. The Manufacturing Resource Technical Requirements section forms the bulk of this document and contains the actual tables of manufacturing resource requirements. A brief Conclusion, a statement of the Future Plans for the information contained in this document, and a detailed Bibliography follow.

Technical Discussion

MR information model development requires identification of the common set of MR data which supports the functions performed by a variety of CAE software applications. Many techniques can be employed to identify this set of MR data, including (1) analyzing what MR data is needed by specific CAE applications by investigating the detailed operation of those applications, (2) analyzing existing industry-developed MR databases, (3) assessing the information provided by MR vendors in their product specifications, and (4) reviewing existing national and international standards where appropriate. In fact, this project has utilized all of these approaches. However, if no bounds were set on the scope of these investigations, the requirements gathering phase of this project could be endless. With that in mind, the project has set bounds on the investigation as determined by the manufacturing environment the data is intended to support.

Resource Data Scope

Several factors influenced the determination of a scope for the MR data analysis. An essential factor was the manufacturing methods of interest to the NCMS RRM consortium members. In their joint efforts, the consortium members were largely focused on improving the design to production cycle time for parts produced by milling, drilling, and/or turning. The materials for the consortium's part families included aluminum, carbon steel, Kovar (nickel-based steel), and titanium. Based on these constraints, the following manufacturing resource types were deemed to be "in-scope:" ²

Machine Tools
N-Axis milling machines - processes: mill, drill, bore, ream, tap, saw
N-Axis turning machines - processes: turn, bore, thread, groove, face, profile, cut-off
Combination milling/turning machines
Cutting Tools
mills, drills, taps, countersinks, counterbores, reamers, boring tools, lathe tools
including solid cutting tools, insertable tools, and brazed tools
Inserts
Cutter Assembly Components
clamps, screws, shims, chipbreakers, interchangeable pilots, etc.
Tool Holders
Arbors
Adaptors
Collets
Bushings
Tooling Assemblies
Tooling Assembly Components
collet nuts, spacers, retention knobs, arbor retaining bolts, etc.
Cutting Tool Materials

The simplifying assumption was made that the starting state of the work-in-process would be "ready-stock," meaning that no blanking or stock preparation processes would be considered. Based on these constraints and assumptions, the following manufacturing operations/technology areas were deemed to be "out-of-scope:"

Grinding	Laser Cutting
Casting	Water Jet Cutting
EDM	Welding
Extrusion Milling	Broaching
Band Sawing	Planing
Sheet Metal Parts & Processes	Modular/Proprietary "Quick-Change" Tooling ³

Another factor affecting the scope of the MR data analysis was consideration of how much of the product lifecycle or production process was to be considered, e.g., material resource planning, factory scheduling, off-line inspection, and so forth. It was decided that the manufacturing engineering activities within the production cycle to be considered would be limited to manufacturing cost estimating, manufacturing process planning, and NC program generation. This decision was based on several factors, notably the detailed use of manufacturing resource information that these processes require. Among the consequences of this decision are: 1) information relating to status of equipment for scheduling purposes is not covered, and 2) administrative information which might be used for accounting, inventory, or maintenance purposes is also not covered.

Finally, the scope of the information contained in this document is not intended to be specific to U.S. equipment, practices, or standards. Conscious effort has been made to ensure that a broad spectrum of international resource information has been taken into account. At the same time, the project cannot guarantee that every applicable U.S. or European or other manufacturing resource style, type, usage, or standard has been examined. The authors endeavor to seek widespread review of this document with the hope that further enhancements to the information covered will result.

Data Analysis Methodology

Multiple representations of existing MR data have been analyzed to review the current state-of-the-practice and to form a baseline from which to begin. MR data representations in resource vendor product specifications, manufacturing handbooks, technical journals, CAE application software documentation, industry-developed databases, as well as national and international standard documents have been examined in detail during the course of this effort. The project has also sought, and continues to seek, expertise from practitioners in the fields of manufacturing equipment production and use. In general, the project has acquired a large amount of "raw" information about manufacturing resources in the domain of interest. A great deal of effort was required to analyze the raw information such that commonalities could be identified and accurately compared.The sources of MR information and issues relevant to the particular analysis efforts are discussed in the following sections.

The reader is referred to the Bibliography for a comprehensive list of references.

Documentation Method for MR Requirements

The challenge for this project has been to collate the "raw" resource data into a format which captures the needs of the intended users (e.g., manufacturers, CAE applications, tooling vendors), is self-consistent, is comprehensible, and does not contradict common industry nomenclature. The documentation methods described in this section reflect the work that this project has performed to address that challenge. This section can be viewed as an overview of the proposed data structure and a tutorial on how to read the manufacturing resource tables. Excerpts from the tables are used to illustrate various points. In some instances, it may be beneficial to refer directly to the manufacturing resource tables to understand specific concepts.

The authors have assumed that the reader has a working knowledge of machine tools, cutting tools, and related components. Resource descriptions are brief. Each description is intended to clearly indicate which familiar aspect is being described, not necessarily to educate the reader about what that aspect is or why it is important. However, the authors do want to ensure that the reader can understand how the requirements are being presented in this document. To that end, the following sections describe how the requirements have been documented and provide the reader with the basic information necessary to interpret the requirements.

Manufacturing Resource Taxonomy and Relationships

The manufacturing resources identified in this requirements specification are grouped into categories sharing similar characteristics. In general there are two groups of resource information: tooling assembly (i.e., cutting tools, inserts, tool holders, etc.) information and machine tool information. Within each of these two broad groups, there are multiple categories defining resource information according to the details of those resources. The categories are represented as tables; each table contains three major components. The first is the table name - it describes what kind of manufacturing resource is being defined. The second major component is the first column of the table - it is a list of the attribute names used to characterize the resource. The last major component is the second column of the table - it provides the definitions/descriptions for the attributes in the corresponding rows.

We have adopted the mechanism of inheritance from the world of object-oriented computer programming to minimize the size of the tables necessary to define all of the resources within the scope of this project. Classifying resources into a hierarchical structure enables the identification of subtables, which inherit resource attributes from their "parent" table. There can be multiple levels of subtables; each inherits all of the resource attributes from the table at the next level higher in the hierarchy. Along with its name, each table is identified with a table number that conveys its location in the hierarchy and identifies its parent table (if one exists). Conversely, each parent table has a special attribute present in the first row of the table. This subtype attribute enumerates the names of the subtables which inherit the attributes defined for this (parent) table.

Figure 1

depicts an excerpt from the resource tables. The table identification number "IIIA1" indicates that the TWIST_DRILL table is a subtable of another table. In this case, the table one level higher in the hierarchy is numbered "IIIA", i.e., the DRILL table. Therefore, TWIST_DRILL inherits all of the attributes defined in the DRILL table. The subtype attribute in the first row of the TWIST_DRILL table in Figure 1 indicates that there are two subtypes of TWIST_DRILL, namely CORE_DRILL and STEP_DRILL. The table numbering scheme used in this document results in the CORE_DRILL and STEP_DRILL tables having table numbers "IIIA1a" and "IIIA1b", respectively. CORE_DRILL and STEP_DRILL inherit all of the attributes from their parent table, i.e., TWIST_DRILL. Since these subtables inherit all of the attributes from both DRILL and TWIST_DRILL, only the attributes which are specific to CORE_DRILL and STEP_DRILL are defined in tables "IIIA1a" and "IIIA1b".

The hierarchical organization for tooling assembly and machine tool resource tables is illustrated in Figures 2 and 3, respectively.

The figures show the connections between "parent" tables and their subtypes. The tables furthest to the left in the diagrams have no parent tables, while the tables furthest to the right have several "ancestors" and thus inherit attributes from each of the them. The figures also illustrate the table numbering scheme by clustering the table names under the appropriate levels.

Figure 2 depicts the organization of the tables characterizing tooling assembly resources. Considering the CORE_DRILL example again, Figure 2 shows that CORE_DRILL is a subtype of TWIST_DRILL, which is in turn a subtype of DRILL, which is a subtype of TOOL_BODY. In this document a notation has been adopted to designate the path to a particular table, e.g., TOOL_BODY:DRILL:TWIST_DRILL:CORE_DRILL denotes the path to the CORE_DRILL table. In order to refer to a specific attribute in a table, the name of the attribute is appended to the path but separated by a period, e.g., TOOL_BODY:DRILL:TWIST_DRILL:CORE_DRILL.CHAMFER_ANGLE denotes the "Chamfer Angle" attribute in the CORE_DRILL table.

A resource table may rely on linkages (or references) to other tables to fully characterize the resource of interest. A typical example is the characterization of TOOL_ASSEMBLY. Given that a complete tool setup usually involves a combination of holders, adaptors, the cutting tool itself, and possibly other tooling components, it is not surprising that the characterization of this information requires a mechanism allowing one resource table to reference others. Figure 4 illustrates an example of a tool assembly consisting of a retention knob, collet chuck adaptor, collet, twist drill, and a collet nut. Together this example would comprise what is denoted in the cutting tool resource tables as TOOL_ASSEMBLY.

To carry through with this example, Figure 5 illustrates how the TOOL_ASSEMBLY table is linked to CUTTING_TOOL, TOOL_HOLDER, and TOOL_ASSEMBLY_COMPONENT tables. Since DRILL and all other tools are subtypes of CUTTING_TOOL, the TOOL_ASSEMBLY table need only refer to CUTTING_TOOL to allow any tool to be included in the assembly.

The notation used in this document to specify a linkage from one table to another is <Reference to TABLE_NAME> as shown in the first attribute of Figure 6. Note that Figure 6 depicts another excerpt from the resource tables. The <Reference to TABLE_NAME> notation designates the attribute CUTTING_TOOL_INFORMATION to be a link from the TOOL_ASSEMBLY table to the CUTTING_TOOL table.

When there is the potential for multiple tables of the same type to be linked to a specific table, a different linkage mechanism is used. The sample tool assembly shown in Figure 4 requires two tool holding components, i.e., the collet chuck adaptor and the collet itself. These components are represented by the COLLET_CHUCK_ADAPTOR and COLLET tables, respectively. COLLET_CHUCK_ADAPTOR is a subtype of ADAPTOR, which is in turn a subtype of TOOL_HOLDER; COLLET is a direct subtype of TOOL_HOLDER. Thus, the two holding components can be linked to the TOOL_ASSEMBLY table via a reference at the TOOL_HOLDER level as illustrated in Figure 5. Similarly, the retention knob and collet nut of Figure 4 are both examples of TOOL_ASSEMBLY_COMPONENTs. This dictates the need for multiple references from TOOL_ASSEMBLY to TOOL_ASSEMBLY_COMPONENT.To allow for the linkage of multiple tables of the same type, the LIST OF <Reference to TABLE_NAME> notation is used in this document as shown in the second and third attributes of Figure 6.

There are situations where a characteristic of a resource has been identified during the requirements gathering process, but it has been determined that the attribute may not be required for some applications or uses. For example, a particular tool holding configuration may not include any of the auxiliary components from the TOOL_ASSEMBLY_COMPONENT tables. To accommodate such cases, the OPTIONAL keyword is applied to the TOOL_ASSEMBLY_INFORMATION attribute in Figure 6 to indicate that no value for the attribute is required.

References are used in several tables to establish connections between resources and the other resources they may use. The linkage approach is intended to minimize redundancy in table characteristics, while at the same time reflecting how resources relate to one another in practice. Figure 7 identifies the resource tables comprising a tool assembly and the structure of the references between tables as defined in this document. This figure identifies the tables containing links, along with the referenced tables. The arrows between the boxes are oriented such that the head of the arrow points at the table being referenced. When a variable number of table references may be required, the arrow head is labeled with the word LIST, otherwise the arrow is unlabeled to indicate that a single table reference is called for. Arrows drawn with a broken line indicate that the table reference is OPTIONAL; arrows drawn with a solid gray line indicate that the table reference is CONDITIONAL, i.e., dependent on the value of another attribute or some other information. The notation ONE OF in Figure 7 indicates that one of the options is required.