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`FORD 1015
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`

`
`By Martin R. Wagner
`ICAD, Inc.
`
`Page 2 of 167
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`FORD 1015
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`

`
`Trademarks:
`ICAD
`
`The ICAD System,
`ICAD Design Language, IDL
`
`Shape Data, Ltd.
`Sun Microsystems, Inc.
`AT&T
`Siiicon Graphics, Inc.
`Adobe Systems, Inc.
`Oracle Corporation
`Computervision,
`a Prime Computer Company
`
`McDonnell Douglas
`Systems Integration Company,
`Manufacturing and Engineering Systems
`Bentley Systems Inc.,
`an Intergraph affiliate
`
`Dassault Systemes
`Autodesk, Inc.
`
`Parasol id
`SPARCstation
`UNIX
`IRIS
`Postscript
`ORACLE
`CADDS4X
`
`UNIGRAPHICS II
`
`MicroStation
`
`CATIA
`Auto CAD
`
`The trademark information listed above is,
`to the best of our knowledge, accurate and complete.
`
`ICAD, Inc.
`201 Broadway
`Cambridge, Massachusetts 02139
`(617) 868-2800
`
`Copywrite © 1990 by ICAD, Inc. All rights reserved. This book may not be
`reproduced in whole or in part, by mimeograph or any other means, without
`permission. For information address: ICAD, Inc., Attn. Marketing
`
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`Table of Contents
`
`1 Introduction
`About Understanding The !CAD System
`About ICAD
`Learning to Use The ICAD System
`2 Knowledge-based Engineering and The ICAD System
`What is Knowledge-based Engineering?
`Typical Knowledge-based Engineering Applications
`3 Example of an Engineering Problem
`Introduction
`About Mold-base Design
`4 Modeling an Engineering Problem Using ICAD
`Introduction
`Planning an ICAD Product Model
`Writing Defparts and Generating Design Instances
`Writing Engineering Rules
`Creating the Product Structure
`Rule Dependencies in the ICAD Product Model
`Modularizing the ICAD Product Model
`Modeling with Simple Geometric Primitives
`Additional !CAD-supplied Geometric Parts
`Developing Complex ICAD Product Models
`End-user Interfaces for an ICAD Product Model
`Summary of Chapter 4
`5 Integrating ICAD Into an Existing Engineering Environment
`Introduction
`Inputs to The ICAD System
`Outputs from The ICAD System
`Integration Tools and Strategies
`Summary of Chapter 5
`6 Appendix
`Glossary
`
`1-1
`1-3
`14
`
`2-1
`2-17
`
`3-1
`3-2
`
`4-1
`4-4
`4-9
`4-20
`4-29
`4-45
`4-49
`4-56
`4-62
`4-66
`4-71
`4-75
`
`5-1
`5-9
`5-13
`5-20
`5-25
`
`6-1
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`Chapter 1
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`Introduction
`
`1-1
`
`About Understanding The /CAD System
`
`Who Should Read Understanding The /CAD System
`
`Understanding Tlie ICAD System is for all members of the engineering and
`manufacturing team, including managers, who are considering using The ICAD
`System. The ICAD System, ICAD's knowledge-based engineering product, is used
`to develop knowledge-based engineering applications. Understanding The !CAD
`System introduces and defines the terminology of The ICAD System, examines
`some of the techniques used to develop an application using The ICAD System,
`and discusses some of the strategies used to integrate such an application into
`an existing engineering environment.
`Understanding The !CAD System answers the following questions:
`
`• What is The ICAD System, and what differentiates it from other computer(cid:173)
`aided-engineering design tools?
`
`• What types of engineering problems can be automated using The ICAD
`System?
`
`• What are the capabilities of The ICAD System and how can.they be used to
`create solutions to complex, large-scale, real-world engineering problems?
`
`• How can an ICAD knowledge-based engineering application be integrated into
`an existing engineering and computing environment?
`
`In a sense, Understanding Tlie !CAD System is a technical overview of The
`ICAD System. Since the concepts of using The ICAD System are new and
`unfamiliar to most engineers, the essential features of The ICAD System are not
`described on a feature-by-feature basis as with most technical overviews, but
`rather as they apply to a particular application.
`We show in detail how The ICAD System is used to create an engineering
`application that automatically designs mold bases for plastic injection molding.
`Although the concepts of knowledge-based engineering and The ICAD System
`are described in the context of a mold-base design, these same concepts are
`applicable to many engineering domains, and have been used successfully for
`many different kinds of products in many different industries.
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`About Understanding The /CAD System
`
`Chapters
`
`Understanding The ICAD System is divided into the following chapters:
`
`"Introduction"
`
`Discusses the purpose of Understanding The ICAD System,
`gives a brief history of ICAD, Inc., and describes the support
`that ICAD gives its customers to help them become
`successful users of The ICAD System.
`"Knowledge-based Engineering and The ICAD System"
`Provides an overview of knowledge-based engineering and
`lists some of the benefits realized using such a system. This
`section includes a definition of knowledge-based engineering,
`a comparison of knowledge-based engineering with other
`computer-aided engineering technologies, and a discussion of
`different kinds of applications that have been developed
`successfully using The ICAD System.
`"Example of an Engineering Problem"
`Describes the problem of designing a mold base for plastic
`injection molding. The rest of the document shows how The
`ICAD System applies to this problem.
`"Modeling an Engineering Problem Using ICAD"
`Describes the capabilities of The ICAD System by showing
`how they are used to develop a mold-base application.
`"Integrating ICAD Into an Existing Engineering Environment"
`Shows how an application created using The ICAD System
`can be integrated into an engineering environment that
`includes various analysis systems and CAD systems.
`Includes a glossary of concepts and terminology used by
`ICAD.
`.
`
`"Appendix"
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`Introduction
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`1-3
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`About ICAD
`
`ICAD Inc. develops and markets The ICAD System, an advanced knowledge-based
`engineering software package for mechanical product and process design
`automation. At the end of 1989, ICAD Inc. had installed more than 300 ICAD
`systems in manufacturing and engineering firms throughout the world. The
`company's list of customers includes a number of leading manufacturing
`companies in many different industries, such as automotive, aerospace, industrial
`equipment, consumer products, etc.
`In 1984 the founders of ICAD Inc. began the development of The ICAD System
`under a consulting contract with a major CAD company to provide a system that
`would automate the design of heat exchanger units for a major industrial
`equipment manufacturer. The manufacturer recognized that although all heat(cid:173)
`exchanger designs were based on similar engineering principles, each new
`individual design had to be completely redeveloped.
`The manufacturer had attempted automating the design of heat exchangers
`using a traditional CAD/CAM system and a FORTRAN program that added a
`parametric design capability. As they began programming the design process,
`they recognized this would require a much greater programming effort than
`originally anticipated.
`ICAD's founders addressed this issue by developing The ICAD System, which
`uses a knowledge-based engineering approach and object-oriented programming
`techniques. The company's founders shared the vision that new software
`technology provided an opportunity to re-think the conventional approach to
`computer aided design, which is based on computer representation of drawings.
`Their experience with CAD systems convinced them that to do more than help
`edit drawings, the system would require a complete model containing all the
`factors that determine the design, including company standards, procedures, and
`processes. With such a model, a computer system can integrate the entire design
`and manufacturing process, constructing correct designs on demand.
`The early version of The ICAD System successfully automated the design of heat
`exchangers. Since that time, many other applications in different industries have
`been automated successfully as well. ICAD's comprehensive approach to
`engineering automation has enjoyed market acceptance, enabling the company to
`grow rapidly.
`
`- - - · - - -
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`1-4
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`May 1990
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`Learning to Use The ICAD System
`
`!CAD provides you with the support you need to develop successful applications
`using The ICAD System. We provide various kinds of assistance and training to
`enable you to change from a newcomer to knowledge-based engineering design to
`an experienced !CAD Design Language designer. Our goal is capability transfer:
`we transfer our expertise to you so that you become an effective user of our
`tools.
`
`• Intensive training
`
`The basic course, Intensive Introduction to the /CAD Design Language,
`includes both lectures and labs. In addition to learning the basics of The
`ICAD System, you learn techniques that help you select and execute a
`complex, real-world project in conjunction with your ICAD consultant. By the
`time the basic course has been completed, many customers have already
`completed a project with significant real-world savings. ICAD also provides a
`course on using the ICAD Surface Designer.
`
`• Expert consultants
`
`During training you are assigned a personal consultant to help you plan your
`application and break through learning barriers. ICAD's consultants are
`experienced mechanical engineers who have worked extensively on knowledge(cid:173)
`based engineering projects.
`
`• Comprehensive documentation
`
`The ICAD System is completely and thoroughly documented. The
`documentation includes a section on every ICAD Design Language feature
`including a description of the feature, a syntax diagram, and many complete,
`working examples of use. In addition, on-line help is available in the ICAD
`user interface, the ICAD Browser.
`
`• Extensive customer support
`
`Customer support is available via telephone, FAX, or electronic mail to answer
`any technical question or resolve any technical problem with installation, use
`of The ICAD System, or use of the hardware platform.
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`Chapter 2
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`Knowledge-based Engineering and The ICAD System
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`2-1
`
`What is Knowledge-based Engineering?
`
`Keywords: Knowledge-based engineering (KBE), product model, ICAD product
`model, rule-based system, concurrent engineering, parametric CAD systems,
`variational CAD systems, engineering-automation languages, expert systems
`
`Overview
`
`This section introduces the concept of knowledge-based engineering and includes
`the following topics:
`
`• A definition of knowledge-based engineering.
`
`• A comparison of knowledge-based engineering with the traditional design
`process.
`
`• An introduction to the product model, including typical engineering rules
`included in a product model.
`
`• A discussion of some of the benefits realized from using knowledge-based
`engineering.
`
`• A comparison of knowledge-based engineering with other technologies such as
`traditional CAD systems, modern parametric and variational CAD systems,
`engineering-automation languages, and expert systems.
`
`Definition of Knowledge-based Engineering
`
`The ICAD System is a knowledge-based engineering system. Knowledge-based
`engineering, sometimes referred to as KBE, is an engineering method in which
`knowledge about the product, e.g., the techniques used to design, analyze, and
`manufacture a product, is stored. in a special product model (in The ICAD
`System, the product model is called an ICAD product model).
`The product model represents the engineering intent behind the geometric
`design; it captures the how and why, in addition to the what, of the design. It
`can store product information -
`attributes of the physical product such as
`geometry, material type, functional constraints, etc. -
`as well as process
`information -
`the processes by which the product is analyzed, manufactured,
`and tested. Unlike a CAD model which mostly contains geometric information, a
`knowledge-based engineering product model contains all the information required
`by the design.
`Once engineering knowledge about the product is collected and stored as a
`product model, design engineers can generate and evaluate new designs quickly
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`What is Knowledge-based Engineering?
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`and easily by changing the input specifications for the product model, or modify
`designs by extending or changing the product model. This frees the engineer
`from time-intensive, detailed engineering tasks such as repetitive calculations
`and allows more time for creative design work.
`
`The Traditional Design Process Based on a Well-understood Design Strategy
`
`Consider the design of a crankshaft by an engineering team at an automotive
`company. The team is given requirements such as horsepower, number of
`cylinders, torque, and rpm, and is expected to design a new crankshaft that
`minimizes cost and maximizes fuel economy. Assume that collectively the
`engineers have a clear and well-understood strategy for designing crankshafts,
`that is, they have already designed many crankshafts. However, their collective
`experience is distributed among a group of people with varying ability and
`covering several engineering domains.
`Using traditional design methods in conjunction with CAD technology, the team
`integrates the input specifications with the constraints and stated goals. All the
`collective previous experience of designing crankshafts is manually incorporated
`into the new design. While the CAD system can help design the product
`geometry, it provides little help for calculating the engineering design attributes
`such as the required bearing load based on the number of cylinders, horsepower,
`and torque, or for taking into account other factors such as material constraints,
`cost considerations, and manufacturability.
`Once a preliminary design is created, it is frequently analyzed using one of the
`many available FEA (Finite Element Analysis) programs and modified
`accordingly. Finally, the team generates drawings and reports that document the
`crankshaft design.
`Even with all of engineering team's experience, the process of developing a
`single design is laborious, repetitive, and subject to error. If the input
`specifications change at any time, the entire process must be repeated. For these
`reasons, a new crankshaft design typically takes from four to six months to
`complete.1
`This scenario is typical of the traditional design process, in which engineers use
`CAD software to create, manipulate, and display geometry-based product-design
`data interactively. Traditional CAD systems allow engineers to process designs
`faster than when designs were done completely by hand, but go only part of the
`way toward providing a completely flexible tool for adapting to changes in a
`product design. No matter how sophisticated the software tools are, systems that
`use only geometric data to describe a product are limited in their ability to
`automate the design and engineering process since they provide no means of
`capturing the engineering expertise behind the design.
`
`1According to a current ICAD customer.
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`Knowledge-based Engineering and The ICAD System
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`2-3
`
`What is Knowledge-based Engineering?
`
`The following diagram illustrates this traditional design process. Since the
`repetitive, detailed engineering tasks are not automated -
`they need to be done
`by humans -
`they create a bottleneck that slows down the design cycle. While
`the engineers use CAD systems to manage the geometric information and
`generate drawings, other design knowledge, including catalogs, databases, and
`engineering standards, must be managed separately without integrated tools.
`Finally, since this design process is really a loop which repeats until a
`satisfactory design is found, the effect of the bottleneck is multiplied by the
`number of times the loop is repeated.
`
`Start +
`
`Data/information sources
`
`Existing
`Designs
`~--.......i... __ __. Engineering
`----1 Tables
`
`___ _, Standard
`Parts
`
`----1 Catalogs
`
`CAD
`System
`
`Geometry
`
`Inputs
`_...-----+
`Input Specifications
`Constraints
`Change Input
`Refinements
`specifications and
`reconsider constraints. L----..----(cid:173)
`e e
`I No
`' ' Engineering knowledge
`
`Entlre loop must be
`repeated.
`
`Generated manually
`
`Finished
`
`Bills of
`Material
`
`Cost
`Analysis
`
`Design Outputs
`
`Annotated
`Drawings
`
`Generated from
`CAD system
`
`..
`
`NC Tool ~
`""-•P•m•h . . ...wi....:::..JJ
`
`The traditional design process. The design bottlerieck - the time-consuming, repetitive parts of the
`design process - is shown by using heavy lines. Based on inputs and engineering data and
`information, the engineer generates geometric outputs on a CAD system and manually creates
`non-geometric outputs such as BOMs and cost analyses.
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`What is Knowledge-based Engineering?
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`The Same Design Process Using a KBE System
`
`Suppose this engineering team had previously used The ICAD System to develop
`a product model of a crankshaft that automates much of the routine and detailed
`engineering work. 2 If a new request for a crankshaft comes in, a design
`engineer on the team just feeds the new input specifications directly into the
`product model. The model asks the engineer some key questions about the
`application, and then generates a design that incorporates all of the input
`specifications, meets the constraints, and maximizes fuel economy while
`minimizing production costs. The design is sent to a FEA automatically, and the
`design engineer can easily modify the design either by changing the answers to
`some of the key design questions or by modifying the input specifications.
`Finally, the result already contains the document set for the crankshaft, e.g., the
`drawings, reports, and manufacturing plans. A more extensive ICAD product
`model could also produce a tooling plan. New inputs can be used to regenerate a
`new design easily. With the product model, generating a new crankshaft design
`can be done in two days by a single design engineer, as opposed to four to six
`months with traditional methods.
`the repetitive
`In this scenario, the bottleneck of the traditional design process -
`tasks that had to be done by an engineer -
`is eliminated. All such tasks are
`managed by the product model. The design loop can be repeated efficiently as
`many times as necessary.
`The following diagram illustrates the design process using a product model. The
`center of the design process is the product model, which manages all the routine
`engineering tasks. The role of the engineer is to provide the input specifications
`and make the important design decisions. Catalogs, databases, standards books,
`etc., are all integrated into the product model. Outputs are all generated
`automatically by the product model.
`
`2The effort involved m developing a product model is discussed later m this
`section.
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`Knowledge-based Engineering and The ICAD System
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`2-5
`
`What is Knowledge-based Engineering?
`
`Change input
`specifications and
`reconsider constraints.
`Entire loop must be
`repeated.
`
`(
`
`No
`
`Data/information sources are
`integrated into the ICAD
`product model.
`
`Existing
`Designs
`-----i.. __ __. EnglnGering
`__ __.Tables
`
`__ __.. Standard
`Parts
`------' Catalogs
`
`Interaction between users and
`ICAD product model during the
`creation of a new design instance
`
`Start
`
`i
`l
`L--------
`
`Inputs
`Input Specifications
`Constraints
`Refinements
`
`ICAD
`Product
`Model
`
`l
`
`Yes l
`
`Finished
`
`Bills of
`Material
`
`Cost
`Analysis
`
`Product
`Geometry
`
`Design Outputs
`
`Annotated
`Drawings
`
`NC Tool ~
`.._P!!!!a!!!!th!!!!!!!!!!!!!!!!!.l ~
`
`The design process using a KBE product model. The repetitive parts of the design process
`are managed by the product model, which eliminates the design bottleneck.
`
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`2-6
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`.. May 1990
`
`What is Knowledge-based Engineering?
`
`Clearly, there is a certain amount of effort involved in developing the product
`model. In practice, development time varies by application and by required level.
`of detail; typically, it takes slightly more time to develop a product model than it
`does to create a single design using the traditional design process. 3 The time
`benefits of developing a product model compared with using traditional design
`techniques are shown in the following diagram.
`
`Time
`
`Traditional design process
`using CAD system
`
`Design process
`using a KBE
`product model
`
`Number of
`Designs
`
`Time benefits of using KBE compared with the traditional design process. The squares represent
`new designs.
`
`Note that even a partially-developed product model shows substantial time
`benefits since the bottleneck can be widened incrementally.
`
`Using KBE for a Design Process Based on a New Design Strategy
`
`Consider another engineering team that is working on a new, more efficient
`crankshaft based on some recent theoretical or experimental research. Since this
`is a new type of crankshaft, they are developing a completely new strategy for
`
`3Interestingly, the more complex the design, the less time it takes to develop an
`ICAD product model relative to the time it takes to produce a single design
`iteration using traditional design techniques.
`
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`What is Knowledge-based Engineering?
`
`designing such a crankshaft. There are still many benefits to using a knowledge(cid:173)
`based engineering approach even though the design strategy is not well
`understood.
`Using a traditional design process, the team develops an initial design strategy
`which they use to generate an initial crankshaft design. This first design is not
`completely successful, so they change their design strategy and produce a new
`iteration. However, it takes almost as long to produce the second iteration as the
`first, since most of the calculations for important factors such as bearing width,
`joint configuration, counterweight layout, etc., have to be completely redone.
`Finally, after many time-consuming design iterations, the team arrives at the
`final design.
`However, if the team uses a knowledge-based engineering system such as The
`ICAD System to develop a product model that represents their initial design
`strategy, the first design can be generated from the product model. Subsequent
`changes to the design strategy can be made by directly modifying the product
`model, which can then be used to generate new design iterations. Much of the
`work done on the previous design iteration can be automatically carried over to
`the new design iteration. This leads to substantial overall time savings.
`Likewise, since each design iteration takes less time, many more iterations can
`be generated before the design is finalized, which leads to a better quality
`design.
`
`Creating a Product Model by Developing a Rule Base
`
`A product model captures the design strategy required to produce a particular
`product from a specification -
`in essence, it is the set of engineering rules used
`to design the product. For this reason, a knowledge-based engineering system is
`often called a rule-based system, and the product model is often called the rule
`base. This set of rules includes standard engineering rules and experiential
`"rules of thumb" that constrain the design, information about manufacturing and
`cost constraints, catalogs of standard materials, parts, and costs, and techniques
`to maximize quality while minimizing cost and production time. You are not
`limited to rules involving geometry; in fact, you can incorporate any knowledge
`about a product design into a product model, including knowledge about the
`processes used to manufacture the product.
`The product model takes an input specification, applies the engineering rules,
`and generates a product design. This product design can include various outputs,
`such as reports of engineering results, data for engineering analyses, 3D
`geometric models that can be downloaded to a CAD system, structured bills of
`materials, and manufacturing instructions.
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`May 1990
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`What is Knowledge-based Engineering?
`
`Product models often include the following kinds of engineering rules:
`
`• Rules that automatically create the part's geometry from the input specifications.
`
`A rule might relate the diameter of an axle to the torque and length. Also, a
`length of shaft within an axle could be sized to fit between two load-bearing
`components whose size and position are based on engineering constraints.
`
`• Rules that calculate engineering properties about the part.
`
`A rule might calculate the maximum load a particular beam can handle based
`on the shape of the beam and its material. Alternately, the selection of beam
`size and material could be based on the required maximum deflection.
`
`• Rules that choose a configuration based on some condition.
`
`A rule might choose one configuration for a component within an axle if the
`axle is above a particular size or weight, and another configuration if the axle
`is below the size or weight.
`
`• Rules that optimize cost, performance, and quality.
`
`A rule might specify that the material used to construct a crankshaft be the
`least expensive material whose properties allow it to meet some input
`constraints.
`
`• Rules that extract information from external databases.
`
`A rule might look up the advertised strength of a material from a material
`table. Typical applications extract standard parts from catalogs, material
`properties from material tables, and design features from feature libraries.
`
`• Rules that communicate with and analyze the results of external engineering
`analysis programs.
`
`A rule might send a particular beam description to an in-house beam analysis
`program for analysis. Other rules might use the results of the analysis as a
`basis for changing aspects of the beam design.
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`2-9
`
`What is Knowledge-based Engineering?
`
`There are a few important qualities of rules in a knowledge-based engineering
`system that make them particularly well suited for typical mechanical design
`problems:
`
`• Rules allow the direct implementation of standards.
`
`Corporate and regulatory standards and "design rules" form a significant part
`of common engineering practice. These rules can be implemented directly in
`the product model, resulting in product designs that always conform to these
`standards.
`
`• Rules record design intent.
`
`Product models provide a clear reason for every dimension, design decision,
`and configuration. This information is invaluable to the designer and to those
`who review the design.
`
`• Rules do not have to be exact.
`
`Many real-world problems do not have exact theoretical solutions, yet "rule-of(cid:173)
`thumb" techniques for handling these problems are well developed.
`
`Benefits of Using a KBE System
`
`Our customers have realized many benefits from using ICAD's knowledge-based
`engineering system. These include:
`
`• Reducing time to market by automating repetitive designs.
`
`Although most new products are variations of current products, each new
`product design starts from scratch. However, similar products share many of
`the same routine engineering tasks; they are designed from similar
`components using similar engineering techniques, and are analyzed and
`produced in similar ways. Engineers must repetitively perform tedious (and
`sometimes inaccurate) calculations and look up numerous table and catalog
`entries. Much time is spent repeating analyses that optimize product designs.
`A knowledge-based engineering system helps to automate these routine
`engineering tasks for similar products by representing the knowledge of how
`to accomplish them as rules in a product model. This frees engineers to spend
`more time for creative designing.
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`What is Knowledge-based Engineering?
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`• Capturing engineering expertise.
`
`Some experience can be lost permanently when the key design people leave
`the company. A knowledge-based engineering system captures their design
`knowledge so that it is available in the future.
`
`• Facilitating concurrent engineering.
`
`Typically, different engineering disciplines work separately and sequentially on
`the same product design. Any change to the design requires each engineering
`discipline to reevaluate their portion of the design. A product model
`synthesizes the constraints and engineering rules from all engineering
`disciplines; it checks that a design change made by one engineering group
`does not contradict the engineering rules and constraints from the other
`group.
`
`• Providing a fully documented design process.
`
`In most companies, the "knowledge" of how to design and manufacture a
`particular process is scattered throughout the organization in the form of
`drawings of past designs, reports, design notebooks, engineering standards
`books, and the experience of a few key people. Often it takes much time and
`effort to reorganize this knowledge for a new design. This can cause many
`problems, including high engineering and manufacturing costs, slow response
`to customer requests, and bottlenecks caused by the unavailability of a few
`key people. A product model supplies a deterministic design process that
`generates consistent results.
`
`• Integrating catalogs and databases.
`
`Engineers spend too much of their time searching for entries in catalogs and
`laboriously incorporating the results into their designs. A product model links
`to catalogs and databases and looks up the appropriate entries automatically.
`
`• Generating drawings and reports.
`
`Another large part of engineering time is spent annotating CAD drawings and
`writing engineering reports such as bills of materials. A product model can
`include design rules that capture drawing intent as well as report
`specifications. These rules allow the product model to generate annotated
`drawings and reports.
`
`Page 21 of 167
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`FORD 1015
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`

`
`Knowledge-based Engineering and The ICAD System
`
`2-11
`
`What is Knowledge-based Engineering?
`
`• Integrating analysis tools into the design process.
`
`Frequently, the design engineer uses software analysis tools to assist in
`solving specific problems. These tools are not easily integrated into the
`traditional design process since they require input in a specific format.
`Generating input in that format is difficult and time consuming. A product
`model can generate the inputs to the analyses routines directly as part of
`generating a new design. In addition, a product model can read the results of
`the analysis routines and use them to alter the design, forming a closed
`analysis loop.
`
`• Integrating design and manufacturing.
`
`In many companies, manufacturing and engineering departments are
`physically separated and engineering design is often not integrated with
`manufacturing until the design is essentially complete. Any change to the
`design needed to meet manufacturing and process-planning constraints can
`require a long and costly redesign. Also, when engineering design and
`manufacturing analyses occur sequentially it is difficult to optimize the design
`for manufacturing, which adds to the cost of the product. A product model
`incorporates manufacturing constraints as well as engineering constraints, so
`that the product design is optimized for manufacturing. Both sets of rules can
`be developed concurrently by the design engineers and the manufacturing
`engineers, respectively.
`
`• Improving quality.
`
`Under pressure to bring new products to market quickly, quality
`improvements for new products are often left incomplete. Since· a product
`model accelerates the optimization process, higher quality products can be
`designed in the same amount of time or less than the time it takes to produce
`a design using traditional design methods. Increasing the number of design
`iterations almost always improves the design quality, since the designer now
`has the time and opportunity to produce "what if?" designs that experiment
`with the input specifications and design strategy. Additionally, many potential
`design mistakes are eliminated because of the consistency of generating a
`design from the same set of rules.
`
`• Lowering product costs.
`
`Unnecessary product costs are often incurred when design changes cannot be
`made quickly and easily. Design and manufacturing en