Integration of a group technology classification and coding system with an engineering database

Integration of a Group Technology Classification and Coding System with an Engineering Database Richard E. Billo, Rob Rucker, Dan L. Shunk, Arizona State University, Tempe, Arizona

data processing activity. Data has been regarded as a vital corporate resource which must be organized so as to maximize its value. I One aspect of corporate databases which has recently received attention is the integrated engineering database. There is a consensus that the engineering database is a critical factor in successful automation of the manufacturing enterprise. It is of such importance that at least three different nonprofit organizations, i.e., Computer Aided Manufacturing International (CAMI), Integrated Computer Aided Manufacturing (ICAM), and Computer and Automated Systems Association (CASA), have chosen to represent the integrated engineering database as the cornerstone of their manufacturing automation strategy.* An engineering database (also termed "CAD database", "design database", "technical database", "design automation database") may be defined as a database containing geometric, physical, technological and other properties of "technical" objects, as well as the relationship between these properties, z In short, the engineering database defines the products. Typical information may include parts lists, part shapes, geometries, materials lists, engineering standards, etc. 2 The integrated engineering database provides a bridge between computer aided design and computer aided manufacturing. Along with storing geometric modeling information and providing data

Abstract Five tools that apply group technology concepts to an engineering database were investigated and compared. The purpose of the investigation was to select the tools with the best ranking in the areas of cost, flexibility, and ease of use. These tools were applied to engineering data from an aircraft structural composites classification and coding schema. The tools include (1) a vendor supplied GT software package, (2) a GT classification schema mapped onto a relational database, (3) a GT classification and coding schema mapped onto a relational database, (4) a vendor supplied GT software package interfaced with a relational database, and (5) a custom developed GT package which directly accesses a relational database. It was concluded from a comparison of five GT design tools that the custom developed GT package was the most advantageous design tool based on evaluation factors which included cost, flexibility, and user-friendliness.

Keywords: Group Technology, Relational Database, Integration, Engineering Database.

Introduction In recent years, the development of corporate databases has become an increasingly important

*D.A. Appleton. "Manufacturing Data Bases", Unpublisheddocument, D. Appleton Co., Manhatten Beach,California, 1982,p. 1.

37

Journal oJ ManuJacturing Systems Volume 6 No. I

for design analysis application programs, the same database may serve to provide data for such functions as tool and fixture design, NC programming and computer aided process planning. In order to achieve many of these CAD and CAM related benefits, the engineering database should be tightly coupled with group technology* (GT). Group technology is a manufacturing philosophy in which similar parts are identified and grouped together so as to take advantage of their similarities in design and manufacturing? A problem in attempting to apply group technology to an engineering database is integration. Currently, all group technology software packages are equipped with their own internal data storage structures. Like many application programs, the package data storage structures are specifically designed to support only the application at hand and do not interface easily with a general purpose, relational or network structured engineering database. There are two primary choices for resolving this problem: (1) develop an interface between the two systems, or (2) maintain duplicate databases. An alternative to these two options is a methodology that maps a group technology schema onto a general relational database structure. Once this is accomplished, a user can use the standard relational database query facilities to obtain "families" of information.

database management system (DBMS), advantages are achieved while disadvantages that are apparent with each when used separately are minimized. A major advantage is the replacement of two separate databases by a single database. This strategy falls within the scope of the ICAM project. Specifically, in the stated requirements for the factory of the future, ICAM discusses in great detail the need for a c o m m o n database to be used "enterprise-wide". 4 Other advantages include the tabular representation of data, relational capabilities, and the choice of a menu-driven or query language storage and retrieval system.

Classification and Coding Schema Figure 1 displays a prototypical GT classification and coding schema as applied to advanced aircraft structural composites. The sole purpose of the schema is to serve as a basis for describing the various tools. It is not postulated to be completely accurate or implementable in a working manufacturing system. The schema is depicted as a series of subtrees representing classification into similar families of information. The percent symbol (%) placed at various locations throughout the tree signifies that "all" branches of the immediately following subtrees should be traversed. For example, in Figure 1 the "%" is placed at the main node (Aircraft Composites Classification). At this point, the user should traverse all three subtrees beginning first with "Part", then "Material", and finally "Configuration". As discussed above, the schema consists ot three major categories: Part, Material and Configuration. "Part" refers to a structural decomposition of the aircraft. For the present discussion, the parts that comprise the trailing edge of a flap will be the parts of interest and will be assumed to be made of composite materials. "Material" refers to the matrix and reinforcement fibers of which the part is manufactured. "Configuration" refers to the form, type and orientation of the materials that comprise the part. GT codes were assigned at the terminal nodes of the classification schema (see Figure 1). As the tree is traversed for classification of a part, the appropriate codes at the terminal nodes of each subtree are concatenated to form an 1l-digit (vari-

Problem Statement The purpose of the present research was to select or develop several tools that integrate a group technology classification and coding schema with a relational model of an engineering database and to conduct a comparative evaluation of the GT design tools. Specifically, the goal was to apply several alternative techniques for classifying, coding, and then retrieving part-related information to and from a relational database. This process was demonstrated through the use of a prototype group technology classification and coding system which depicts part families of aircraft structural composites. The approach of integrating group technology concepts and software with a relational database philosophy was selected for several reasons: by combining the two methodologies into an integrated

38

Journal of ManuJacturing Systems Volume 6 / N o . I

Part

Win? Box I Slat Box Flap Instatlat=on %

Wing FWD Fuselage FWD Int Fuselage AFT Int Fuselage AFT Fuselage

Enter Flap Number

t,00.

Inboard R~b "'A1 '" I Outboard Rib "A4" Actuator Fitting i "A3" 5par "'A2"

Empennage

Nacelle Fairmgs Wing Carry Thru, Polyester Epoxy Phenolic Silicone Melamine

"M11 "" "M 12" "'Mr 3" "'M 14"' "M15"

Nylon Poh(carbonate Styrene-Acrylo-Nitrde Acrylic Vinyl Acetal Polyethiene Fluorocarbon Polyprogylene Polyethertherketone

"M21 "' "M22" "'M23"

Rubber (Natural) Rubber (Artihcial) Urethane Olehmc Styremc

"M31 "' "M32" "M33" "M34"" "M35"

Aram~d (Keylar 49) Alumina Boron Carbon (Graph=te) Fibrous Glass Wires Ceramic Kevlar/Graphite

"Ft 1" "FI 2" "F 13'" "F 13"' "F15" "F 16'" "F1 T ' "F 18"

Ceramic Whiskers Metallic Whiskers Fibrous Glass, Chopped Flakes. Glass Metal Ground Minerals Hollow Spheres. Glass Mineral Fibers Spheres, Glass Spun Metal Wires

"F21" "F~" "F23"" "F24" "'F25-F26" "F2T" "F28" "F29'"

Thermoset

Thermoplastic

Matrix

Etastomer Aircraft Comp Classif. %

Vlaterial %

Continuous

"'M24""

"M25'" "M26"" "M2T" "M28" "'M29"M2A"

Reinforcement Fiber

Molded

Tape

"'T"

I Broad~ood Form

I Filament/tow I Woven I Nonwoven Rib/Skin I Honeycomb

I

;onfiguration %

Type

Orientation

"'B" "'F" "W'" "N" "R'" "'H"

Prepreg OrY Mold

"'1 '" -2" "'3"

Preferred Random Unidirectional Enter Ply Orientation

"p"R'" "'U"

i

I

Figure 1 Prototype of Aircrsft Structural Composites C l z s s i f i r a t i o n a n d C o d i n g System

39

Journal of ManuJacturing Systems Volume 6/No. I

able) hybrid code that completely represents the part of interest (see Figure 2). Length of the code varies, depending on whether the part is a singlelayered or multilayered composite.

base structure; a vendor supplied GT software package interfaced with a relational database; and a custom developed GT package which directly accesses a relational database. Option 1: Standalone GT System. Many GT support packages are all-purpose tools that can be customized by end users to fit their personal information and decision making needs. Typically, these packages, such as the Decision Classification Information System (DCLASS), are sophisticated subroutine programs with their own database files. In addition, several packages are designed so that they can be called by other programs or, conversely, can call other programs or subroutines. These packages utilize hierarchical or tree structures to classify, store, and retrieve information efficiently and rapidly, to do calculations, and to aid in consistent decision making? The structure of the aircraft structural composites schema as displayed in Figure 1 represents a typical hierarchical s t r u c t u r e of a GT classification and coding schema. Major advantages of such GT software packages center around the ease of initial input and update of the classification schema, and user friendly menu structures for tree traversal. Additional advantages include the ability to retrieve information from partial GT codes, identification numbers, and part attributes. A major disadvantage of such software is their inability to communicate with a general-purpose engineering database. Another disadvantage is the high purchase price and maintenance fees of such softwares. Typically, for a mainframe version, GT packages range in price from $50,000 - $150,000. This cost appears particularly unattractive when compared to the $6,000 - $10,000 price range of a typical relational database management system

a. Fixed digit GT code for single-layer composites A2

M !2

I I I

Part

F24

:

~

I I

I I

Matrix

N 3-- P I I I

Fiber

I

Orientation

l Type Form

b. Variable digit GT code for multi-layer composites AI

M 12

Fi 1

I I I

I I I

I I I

Part

Matrix

Fiber

B !-I I I I I

0 45 0 90

I I I :

I

Orientation

JType Form

Figure 2 Description of a GT Code

Alternative Approaches Once a GT classification and coding system is developed, a means for automated processing and retrieval of information must be made available. Traditionally, this function has been accomplished through the use of a standalone GT application program with its own special-purpose file structure. A more desirable alternative, as will be shown, is to have a GT system that accesses a general-purpose, relational database. The following discussion first describes a typical standalone GT system with special purpose database, and then describes four alternate tools for classifying, coding and retreiving part-related information in which a GT schema is mapped onto a general-purpose database. These four G T / D B M S tools are listed as follows: a GT classification schema mapped onto a relational database structure; a GT classification and coding system mapped onto a relational data-

(RDaMS). Option 2: G T Classification Schema Mapped onto a Relational Database Structure. To avoid the problems discussed above, the GT schema can be mapped onto a relational database structure. This is accomplished by "flattening" the hierarchical structure into a two-dimensional matrix. Table 1 displays a matrix or relational table for the aircraft structural composite schema. The table consists of the "part number", "part name", and a series of attributes that describe the composite part. Data has been added to the table for demonstration purposes. Rather than using menus, the user may load or retrieve data

40

Journal of Manufacturing Systerns Volume 6/No. 1

Table 1 Relational Table for Aircraft Structural Composites Schema

PARTNO

PARTNM

MATRIX

REINF

FORM

TYPE

ORIENT

LI832073

ACTUATOR

EPOXY

GLASS

LI832063

ACTUATOR

POLYETH

GLASS

NONWOVEN

MOLD

PREFERRED

NONWOVEN

MOLD

RANDOM

LI832053

ACTUATOR

POLYETH

LI832043

INBD RIB

EPOXY

GLASS

NONWOVEN

MOLD

PREFERRED

KEVLAR

RIB/SKIN

PREPREG

0 45 0 45

LI832033

INBD RIB

EPOXY

LI832023

INBD RIB

EPOXY

KEV/GRPH

RIB/SKIN

DRY

0 45 0 45

KEVLAR

RIB/SKIN

DRY

0 90 0 90

LI832013

INBD RIB

EPOXY

KEV/GRPH

RIB/SKIN

PREPREG

0 90 0 90

In this example, the user refined the query by adding the condition that the reinforcement fiber must be Kevlar. Table3 lists the result of this query. The table now lists only two parts versus the four of the previous figure. The reader may observe that from the present query, the result has been refined so that the only difference between the two parts is the ply orientation (see Table 3). A major advantage of a GT classification relational database structure lies in direct access of information. If an end-user accesses the database frequently and knows the R D B M S query language, then s / h e may prefer this method of access versus the long and repetitive process of the menu-driven structure that makes up most standalone GT systems. In addition, refinement of families of parts is made easy through the query language of the R D B M S . Also, the data is stored in a generalpurpose database and is available for use for other applications. Finally, due to the listing of end results in tabular form, the direct comparison of families of parts is made easy by simple observation of rows of data. D r a w b a c k s of the currently described system are that the user must know or take time to learn the R D B M S query language. This can be quite a task especially for those who use the database infrequently or where j o b assignments are of short duration. A n o t h e r shortcoming of this system is the

through the use of a query language (e.g., structured query language) embedded within the R D B M S . To retrieve information on families of parts, the user enters a command consisting of the attributes for which he is interested. F o r example, to retrieve all inboard ribs made of an epoxy resin, the c o m m a n d may be as follows: S E L E C T all FROM

gttab

W H E R E partnm EQ inbd*rib A N D matrix EQ epoxy The result of this query is shown in Table 2. F o u r part numbers match this query request. Upon close examination of the attributes of these four rows of information, the user observes that the parts are nearly identical, except for differences in ply orientation and reinforcement fiber (see Table 2). If the user wishes to refine the list of retrieved information, s/he may do so by placing additional " A N D " clauses at the end of the query. The following c o m m a n d illustrates this technique: S E L E C T all FROM

gttab

W H E R E partnm EQ inbd*rib and matrix EQ epoxy and reinf EQ kevlar

Table 2 Result of Query 1

PARTNO

PARTNM

MATRIX

REINF

FORM

TYPE

ORIENT

Lf832043 LI832033 LI832023 LI832013

INBD RIB INBD RIB INBD RIB INBD RIB

EPOXY EPOXY EPOXY EPOXY

KEVLAR KEV/GRPH KEVLAR KEV/GRPH

RIB/SKIN RIB/SKIN RIB/SKIN RIB/SKIN

PREPREG DRY DRY PREPREG

0 0 0 0

41

45 45 90 90

0 0 0 0

45 45 90 90

Journat oJ ManuJacturing S.vstems Volume 6: No. I

Table 3 Result of Query 2

PARTNO

PARTNM

MATRIX

REINF

FORM

TYPE

ORIENT

L1832043

INBD RIB

EPOXY

KEVLAR

RIB/SKIN

PREPREG

0 45 0 45

LI832023

INBD RIB

EPOXY

KEVLAR

RIB/SKIN

DRY

0 90 0 90

possibility of long and cumbersome queries due to the large number of attributes typically necessary to describe a part. Option 3: G T Classification and Coding Schema Mapped onto a Relational Database. A modification of the above tool would be to assign a GT code that represented the attributes of the database. Table 4 displays a table that contains a GT code as well as the attributes that describe the composite part. As an alternative to entering long and complicated retrieval commands developed from part attributes, the user can retrieve the same information by executing a relatively short command consisting of the GT code that represented the attributes of interest to him. For example, to retrieve all inboard ribs (GT code: AI) made of an epoxy resin (GT code: MI2), the command is as follows:

contained the characters "A 1", representing inboard ribs, and "M 12", representing epoxy. If the users wishes to refine the retrieved list, s/he may do so by attaching additional codes to the GT code. The following command illustrates this technique: SELECT all FROM

WHERE gtcode EQ AI*M12*FII* In this example, the user refined the query by adding the code for Kevlar as the reinforcement fiber. The result of the query is illustrated in Table 6. To aid the user in learning code assignments, a "help" file can be placed in the RDBMS for easy access and usage. GT coding provides an advantage to the frequent database user by allowing faster retrieval through shorter c o m m a n d entry. In addition, retrievals can be further expedited by placing an index on the "GTCODE" column. A major drawback of the currently described relational database tool is that the user must know the GT code assignments for each attribute. Although an online "help" file can be made readily available, the infrequent user may find this method of query to be burdensome. Option 4: Vendor Supplied GT Software Package Interfaced with a Relational Database. The above described retrieval process can be auto-

SELECT all FROM

gttab

gttab

WHERE gtcode EQ AI*M12* The command is entered such that the GT codes of the attributes of interest are concatenated. The asterisks (*) between codes represent "wildcards" meaning that any single character, combination of characters, or blanks may appear between the designated codes. Table 5 illustrates the result of the query. The RDBMS retrieved all parts that

Table 4 G T Coding Schema Designed into Relational Table

PARTNO

PARTNM

LI832073

ACTUATOR

LI832063 LI832053

GTCODE

MATRIX

REINF

FORM

TYPE

ORIENT

A3 Ml2 F23 N3--P

EPOXY

GLASS

NONWOVEN

MOLD

PREFERRED

ACTUATOR

A3 M27 F23 N3--R

POLYETH

GLASS

NONWOVEN

MOLD

RANDOM

ACTUATOR

A3 M27 F23 N3--P

POLYETH

GLASS

NONWOVEN

MOLD

PREFERRED

LI832043

INBD RIB

AI MI2 Fll RI--0 45 0 45

EPOXY

KEVLAR

RIB/SKIN

PREPREG

0 45 0 45

LI832033

INBD RIB

AI MI2 FI8 R2--0 45 0 45

EPOXY

KEV/GRPH

RIB/SKIN

DRY

0 45 0 45

LI832023

INBD RIB

Al Ml2 Fll R2--0 90 0 90

EPOXY

KEVLAR

RIB/SKIN

DRY

0 90 0 90

L1832013

INBD RIB

AI MI2 Fl8 RI--0 90 0 90

EPOXY

KEV/GRPH

RIB/SKIN

PREPREG

0 90 0 90

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Journal o f ManuJ~tcturing Systems Volume 6/No. 1

Table 5 Result of Query 3

PARTNO

PARTNM

LI832043

INBD RIB

L1832033

INBD RIB

LI832023 LI832013

GTCODE

MATRIX

REINF

FORM

TYPE

ORIENT

AI MI2 FII RI-- 0 45 0 45

EPOXY

KEVLAR

RIB/SKIN

PREPREG

0 45 0 45

Al MI2 Fl8 R2-- 0 45 0 45

EPOXY

KEV/GRPH

RIB/SKIN

DRY

0 45 0 45

INBD RIB

AI MI2 Fll R2-- 0 90 0 90

EPOXY

KEVLAR

RIB/SKIN

DRY

0 90 0 90

INBD RIB

AI Ml2 FI8 R I - - 0 90 0 90

EPOXY

KEV/GRPH

RIB/SKIN

PREPREG

0 90 0 90

mated by interfacing the GT software package with the RDBMS. With this technique, the end user identifies the attributes of interest by traversing the menu-driven tree structure of the GT software. As the attributes are chosen, the GT code is automatically assigned. After all menus have been traversed, rather than storing this information in the GT file structure, a subroutine which has been linked to the GT software is automatically executed, This subroutine down loads the GT code to an external file. The user then logs on to the RDBMS and executes a single procedural executive which unloads the GT code from the external file, automatically queries the database for similar codes and retrieves the information of interest. With this system, the GT software serves only to present the classification and coding schema to the user. All data is stored in the relational database. Unfortunately, however, queries are now a two step procedure. For example, the user must first start the GT package and traverse the menus. S/he must then exit the GT software package and begin the RDBMS executive so that the retrieval process can be completed.

as in the standalone GT system, users classify, code and retrieve information by traversing a series of menus representing the classification schema. However, queries are now processed through both the GT and database procedures in a continuous procedure, thus eliminating the distraction in Option 4 of switching back and forth between software packages. Appendix A lists a sample terminal session to retrieve an inboard rib of an aircraft flap using the RDBMS menus. Using this custom GT tool, users now have the advantages of the previously described tools without the disadvantages described in Option 1 thru 4. For example, a user can retrieve information either by traversing menus, entering GT codes, or using the RDBMS query language. Unlike the standalone GT system with its special-purpose database, information is now stored in a general-purpose relational database, thus making it possible to serve multiple purposes.

Option 5: Custom Developed G T Package. To

Five GT tools have been described for purposes of classification and retrieval of engineering data. Application of these tools has demonstrated the general advantage of utilizing group technology in concert with a relational database for effective database management. Table 7 summarizes the advantages and disadvantages of each tool. Although any decision as to the choice of the most appropriate G T / D B M S tool must be based on the needs of the enterprise, Option 5 which utilizes a custom devel-

Concluding Remarks

avoid the problem discussed above, custom designed GT software that stores and accesses information directly into and from a relational database was developed. By placing query commands within procedural executives available with RDBMS, a program was written that emulated the menus of the GT software package. This made it possible to incorporate the aircraft structure composites classification and coding schema into the RDBMS. Just

Table 6 Result of Query 4 PARTNO

PARTNM

L1832043

I N B D RIB

L1832023

I N B D RIB

GTCODE

MATRIX

REINF

FORM

TYPE

ORIENT

AI MI2 FII RI-- 0 45 0 45

EPOXY

KEVLAR

RIB/SKIN

PREPREG

0 45 0 45

AI MI2FII R2-- 0 90 0 90

EPOXY

KEVLAR

RIB/SKIN

DRY

0 90 0 90

43

Journal oJ ManuJa('turing S.vstems Volume 6, No. I

Table 7

GT Software Tools Comparison of Advantages and Disadvantages Tabular Represent of Data

Retrieve Fr. Code, Part # or Attrib.

Mechanisms

Easy Schema Maintenance

Single Gen. Purpose Database

Mult. Query

Low Cost

High Degree User Friendliness

Total Number Advantages

Standalone GT System

N

Y

N

Y

N

N

Y

2 of 7

Relational Classification System

Y

N

N

Y

Y

Y

N

4 of 7

Relational Classification & Coding System

y

y

N

Y

Y

Y

N

5 of 7

Interlace B / W GT System and R D B M S

Y

N

Y

Y

N

N

N

3 of 7

Custom GT "Front-End"

y

y

y

N

Y

Y

Y

6 of 7

Y = Yes N=No

oped GT "front end" mapped onto a relational database, proved most advantageous in this study based on cost effectiveness, efficiency, and user friendliness. However, there is a major disadvantage to the custom GT package relative to GT schema maintenance. In the Option 5 model, the GT schema was made part of the software program itself. This can lead to cumbersome "update" problems. This disadvantage could be resolved by placing the GT menus directly into the relational database tables or into an expert system that interfaces directly with the R D B M S . In this way, a GT schema developer would need only to update the relational tables or expert system rules while leaving the software unchanged.

= =>2 (1) (2) (3) (4) (5) (6) (7) (8) (9)

PART WING FWD FUSELAGE FWD INTERNAL FUSELAGE AFT INTERNAL FUSELAGE AFT FUSELAGE EMPENNAGE NACELLE FAIRINGS WING CARRYTHRU

(1) (2) (3)

WING BOX SLAT BOX FLAPINSTALLATION

==>1 WING

= => 3 FLAP INSTALLATION ENTER FLAP NUMBER > 3

(1) (2)

EDGE LEADING TRAILING

(1) (2) (3) (4)

TRAILING EDGE INBOARD RIB OUTBOARD RIB ACTUATOR ATTACH FITTING SPAR

(1) (2) (3)

MATRIX THERMOSET THERMOPLASTIC ELASTOMER

(1) (2) (3) (4) (5)

THERMOSET POLYESTER EPOXY PHENOLIC SILICONE MELAMINE

==>2

Appendix A Sample Terminal Session to Retrieve an "Inboard Rib" o f an Aircraft Flap Using R D B M S Menus

==>3

: : > RUN GRPTCH (1) (2) = =>2 (1) (2)

GROUP TECHNOLOGY CLASSIFY A PART RETRIEVEA PART

==>1

RETRIEVE RETRIEVEFROM CODE RETRIEVEFROM ATTRIBUTES

44

Journal of ManuJacturing Systems Volume 6/No. 1

==>2 (1) (2)

REINFORCEMENT FIBER CONTINUOUS MOLDED

(1) (2) (3) (4) (5) (6) (7) (8) (9)

MOLDED CERAMIC WHISKERS METALLIC WHISKERS FIBROUS GLASS, CHOPPED FLAKES. GLASS METAL GROUND MINERALS HOLLOW SPHERES, GLASS MINERAL FIBERS SPHERES. GLASS SPUN METALWIRES

==>2

==>2 PARTNO L1832073-001

PARTNAME ACTUATOR FITrlNG

GTCODE A3 M12 F23 N 3--R

MATRIX EPOXY

(table continued) REINF FIBROUS GLASS

FORM NONWOVEN

TYPE MOLD

ORIENT RANDOM

= = > ESC GROUP

(1) (2)

TECHNOLOGY

PROCESSA PART RETRIEVE A PART

= = > ESC

==>3 (1) (2) (3) (4) (5) (6) (7)

FORM TAPE BROADGOOD FILAMENT/TOW WOVEN NONWOVEN RIB/SKIN HONEYCOMB

(1) (2) (3)

TYPE PREPREG DRY MOLD

(1) (2) (3) (4)

ORIENTATION PREFERRED RANDOM UNIDIRECTIONAL ENTER PLY ORIENTATION

==>3

= =>3

References 1. J. Martin. Computer Data-Base Organization, Prentice-Hall, Englewood Cliffs, New Jersey, 1977, p. 2. 2. W. Eberlein, H. Wedekind. "A Methodology for Embedding Design Data Bases into Integrated Engineering Systems", J. Encarnacao, F.L. Krause. (editors), File Structures and Data BasesJor CA D, Elsevier Science, New York, 1982. 3. M. Groover, E. Zimmers. CAD~CAM, Prentice-Hall, Englewood Cliffs. New Jersey, 1984, p. 275. 4. ICAM Conceptual Design for Computer-Integrated Manufacturing: Factory of the Future Conceptual Framework, 1984, A F W A L / M LTC, Contract No. F33615-81-C-5119. 5. "DCLASS", DCLASS Technical Manual, CAM Software Research Lab, Provo, Utah, 1985.

Author(s) Biography Richard Billo is a Faculty Associate of Industrial and Management Systems Engineering at Arizona State University, Tempe, Arizona. He obtained a B.A. in Psychology from West Virginia University, a M.S. in Psychology from the University of the Pacific, and a M.S. in Industrial and Management Systems Engineering from Arizona State University. Mr. Billo is a consultant in the area of integrated systems design and group technology and is a member of AIIE. Rob Rucker is an Assistant Professor of Industrial and Management Systems Engineering at Arizona State University. He received a M.S. in Engineering Science and a Ph.D. in Industrial and Management Systems Engineering from Arizona State University. Dr. Rucker's interests are in the areas of computer aided processes in manufacturing, database design and information systems, decision analysis, artificial intelligence, simulation, and computer graphics. He is a member of AIIE, IEEE, ASME, and the Association for Computing Machinery (ACM). Dan L. Shunk is Director of the Center for Automated Engineering and Robotics and an Associate Professor, Industrial and Management Systems Engineering at Arizona State University. He is currently on the Board of Directors of SME's Computer and Automated Systems Association and was voted one of S ME's Outstanding Young Engineers in 1984. Previously, Dr. Shunk was Vice President and General Manager at GCA Corporation, Manager of Group Technology at International Harvester, and Manager of Manufacturing Systems at Rockwell International. He began his career as co-founder of the U.S.A.F. Integrated Computer Aided Manufacturing (ICAM) program. Dr. Shunk is an experienced practitioner and consultant in integrated system design, group technology and automated systems. He is a senior member of AIlE and SME.

45