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FORWARD

Unigraphics is one of the world's most advanced and tightly integrated

CAD/CAM/CAE product development solutions. Spanning the entire range of product

development, Unigraphics delivers measurable value to enterprises of all sizes. It

enables making complex product design simpler, thus delivering products to market

faster.

The Unigraphics software integrates knowledge-based principles, industrial design,geometric modeling, advanced analysis, graphic simulation, and current engineering. It

is built atop the industry-standard Parasolid modeling kernel. The software has

powerful hybrid modeling capabilities by integrating constraint-based feature modeling

and explicit geometric modeling. Besides parts of standard geometry, it enables the

design of complex free-form shapes like airfoils and manifolds. It also enables the

merging of solid and surface modeling techniques into one powerful tool set.

This write-up is intended for beginning users of Unigraphics. However, users of

previous versions of Unigraphics may also find this tutorial useful for them to learn the

new user interface and functions. The user will be guided from how to start a

Unigraphics session to using it for various modeling and design applications.

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CHAPTER 1 - INTRODUCTION

The modern manufacturing environment can be characterized by the paradigm

of delivering products of increasing variety, smaller lots and higher quality in the

context of increasing global competition. Industries cannot survive worldwidecompetition unless they introduce new products with better quality, at lower cost and

with shorter lead time. There is intensified international competition and decreased

availability of skilled labor. With the dramatic changes in computing power and wider availability of software tools for design and production, engineers are now using

Computer Aided Design, Computer Aided Manufacturing and Computer Aided

Engineering systems to automate their design and production processes. These

technologies are now used everyday for engineering tasks. Below is a brief descriptionof how computer aided design (CAD), computer aided manufacturing (CAM) and

computer aided engineering (CAE) technologies are used during the product realization

process.

PRODUCT REALIZATION PROCESS

The product realization process can be divided into design and manufacturing. The

design process starts with identification of a new design need that is identified after themarketing personnel gets feedback from customers’ demands. Once the relevant design

information is gathered, design specifications are formulated. Next, a feasibility study

is done with relevant design information. Detailed design and analyses then follow.Detailed design includes design conceptualization, prospective product drawings,

sketches and geometric modeling. Analysis includes, stress analysis, interferencechecking, kinematic analysis, mass property calculations and tolerance analysis, design

optimization, etc. The quality of the results obtained from these activities is directlyrelated to the quality of analysis model chosen.

The manufacturing process starts with the shop-floor activities beginning from production planning, which uses the drawings from the design process and ends with

the actual product. Process planning includes activities like production plan, material

orders, and machine selection. There are varied tasks like procurement of new tools, NC programming and quality checks at various stages during production. Process

planning includes planning for all these activities too. Parts that pass the quality control

inspections are assembled, functionally tested, packaged labeled and shipped tocustomers.

A diagram representing the Product Realization Process is shown below.

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Brief History of CAD / CAM development

The roots of today’s CAD/CAM technologies go back to the beginning of civilization

when graphics communication was acknowledged by engineers in ancient Egypt.

Orthographic projection practiced today was invented around 1800s. The realdevelopment of CAD/ CAM systems started in 1950s. CAD/ CAM went through four

major phases of development in the last century. 1950s was known as the era of

conceiving interactive computer graphics. MIT’s Servo Mechanisms Laboratorydemonstrated the concept of numerical control (NC) on a three axis milling machine.

Development in this era was slowed down by the inadequacy of computers of that

period for interactive use. During late 1950s the Automatically Programmed Tools

(APT) was developed and General Motors began to explore the potential of interactivegraphics.

1960s was the most critical research period for interactive computer graphics. Asketchpad system was developed by Ivan Sutherland, which demonstrated the

possibility of creating drawings and altercations of objects interactively on a CRT

(cathode ray tube). The term CAD started to appear with word ‘design’ extending

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beyond basic drafting concepts. General Motors announced their DAC-1 system and

Bell Technologies announced their GRAPHIC 1 remote display system.

During the 1970s, the research efforts of 1960s in computer graphics had begun to befruitful, and important potential of interactive computer graphics in improving

productivity was realized by industry, government and academia. 1970s is

characterized as the golden era for computer drafting and the beginning of ad hocinstrumental design applications. National Computer Graphics Association (NCGA)was formed and Initial Graphics Exchange Specification (IGES) was initiated.

In 1980s new theories and algorithms evolved and integration of various elements of design and manufacturing was developed. The major research and development focus

was to expand CAD/CAM systems beyond three-dimensional geometric designs and

provide more engineering applications.

In the present day, CAD/CAM development is focused on efficient and fast integration

and/or automation of various elements of design and manufacturing along with the

development of new algorithms. There are many commercial CAD/CAM packagesavailable for direct usages which are user friendly, very proficient and competent.

Some of the commercial packages in the present market are: -

• Autocad, Mechanical Desktop, etc. are some low end CAD software’s which

are mainly used for 2D modeling and drawing.

• Unigraphics, Pro-E, Ideas, Mechanical Desktop, CATIA, Euclid, etc. These are

higher order modeling and designing software’s which are costlier and veryefficient. The other capabilities of these software’s are manufacturing and

analysis.

• Ansys, Abaqus, Nastran, Fluent, CFX – These packages are mainly used for

analysis of structures and fluids. Different software’s are used for different proposes, like Fluent is used for fluids and Ansys is used of structures.

• Alibre, Cyber-Cut, CollabCAD, etc. are the latest CAD/CAM software’s which

focus on collaborative design. Collaborative design is computer aided designingof multiple users working at the same time.

Definition of CAD / CAM / CAE

Computer Aided Design – CAD

CAD is the technology concerned with the use of computer systems to assist in the

creation, modification, analysis, and optimization of a design. Any computer program

that embodies computer graphics and an application program facilitating engineeringfunctions in design process can be classified as CAD software.

The most basic role of CAD is to define the geometry of design – a mechanical part, a product assembly, an architectural structure, an electronic circuit, a building layout, etc.

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The greatest benefits of CAD systems are that it can save considerable time and reduce

errors caused by otherwise having to redefine the geometry of the design from scratch

every time it is needed.

Computer Aided Manufacturing – CAM

CAM is the technology concerned with the use of computer systems to plan, manage,

and control the manufacturing operations through computer interface with the plant’s

production resources.

One of the most important areas of CAM is numerical control (NC). This is the

technique of using programmed instructions to control a machine tool that cuts, mills,

grinds, punches or turns raw stock into a finished part. Another significant CAMfunction is in the programming of robots. Process planning is also a target of computer

automation.

Computer Aided Engineering – CAE

CAE is the technology concerned with the use of a computer system to analyze thefunctions of a CAD created product, allowing designers to simulate and study how the

product will behave so that the design can be refined and optimized.

CAE tools are available for a number of different types of analyses. For example,

kinematic analysis programs can be used to determine motion paths and linkage

velocities in mechanisms. Dynamic analysis programs can be used to determine loads

and displacements in complex assemblies such as automobiles. One of the most popular methods of analyses is using a Finite Element Method (FEM). This approach can be

used to determine stress, deformation, heat transfer, magnetic field distribution, fluid

flow, and other continuous field problems that are often too tough to solve with anyother approach.

Scope of This Tutorial

This tutorial is written for students and engineers who are interested in learning how touse Unigraphics for design of mechanical components and assemblies. Learning the use

of this software will also enable the user to gain knowledge on CAD/CAM systems in

general, which will be valuable to learning how to use other CAD systems such asIDEAS, PRO-E, CATIA, etc. by themselves if they desire so.

This tutorial provides a step-by-step approach for the users to learn the Unigraphics

package. The topics will include – Getting Started with Unigraphics, Form Features,

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Operations on Form Features, Introduction to Drafting, Introduction to Sketch, Free

Form Modeling and Assemblies.

Chapter 1 gives the overview of CAD/CAM/CAE. Here the product realization cycle is

discussed along with the history of CAD/CAM/CAE and definitions of each.

Chapter 2 includes the fundamental Unigraphics essentials from starting a session withWindows or UNIX, and being familiar with print, save, exit a session, etc. It also gives

a brief description of Coordinate System, Layers, various tool boxes and other

important commands, which will be used in later chapters.

The actual designing and modeling of parts begins with Chapter 3. It describes different

features such as reference features, swept features, primitive features, etc. and howthese are used in design with Unigraphics.

Chapter 4 is a continuation of Chapter 3 where various kinds of operations are

performed on features. The different kinds of operations include trim, blend, Booleanoperations and many more.

The user will learn the method of creating a drawing from a model in Chapter 5. In thischapter, we will demonstrate how to create a drawing by adding views, dimension the

part drawings, and modify the various attributes in drawing such as text size, arrow size

and tolerance.

Chapter 6 presents the concept of sketch. It describes the creation of sketches along

with the geometric and dimensional constraints. This chapter is very important since the present day components are very complex in geometry and difficult to model only with

features.

Chapter 7 introduces free-form modeling. The method of modeling curved and smoothsurfaces will be demonstrated.

Chapter 8 teaches the concepts of Assembly modeling and its terminologies. Itdescribes the Top-Down modeling and Bottom-Up modeling concepts. We will use

Bottom-Up modeling to assemble components into a product.

The examples which are used in each chapter are so designed that they will be finally

assembled in the last chapter. Due to this distinctive feature, user should save all the

models that he/she has generated in each chapter.

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