Standards for CAD Data Exchange

• The CAD data is of four types• Shape• Non shape• Design• Manufacturing data

ProductDesign(CAD)

Engineeringand Analysis

(CAE)

CustomerRequirements

ProductDatabases

ManufacturingDatabases

MaterialsPlanning Procurement

Installationand

DistributionFabrication, Assembly & Test Operations

ProductInformation

Management

Product Design

Manufacturing Engineering

Supply Management

Customer

Suppliers

Marketing

ProcessPlanning

Neutral I/F

Neutral I/F

Product Data ManagementCAD data is used throughout

the organization

Typical Situation

Major companyuses CATIA

Major supplieruses I-DEAS

Small supplieruses AutoCAD

Small supplieruses Solid Edge

Partner uses Unigraphics

The Problem

• Every CAD system uses its own proprietary data format

• Design data must be converted from one format to the other

Direct Translation between CAD Systems

• Need a translator from every CAD package to every other

• For 4 CAD packages, need 6 translators

• For 6 CAD packages, need 16 translators!

I-DEAS Unigraphics

Pro/EngineerCATIA

Data Exchange Standards

• To address the problem, many standards for CAD data exchange have been developed

• CAD systems can import and export to many of these standard formats.

• To deal with all CAD systems, you must support I-DEAS, Unigraphics and CATIA ,Pro /E

• For small companies, this is very difficult.

A Better Solution

• A better solution is development of reliable data exchange standards, using a neutral interface

CAD 1 CAD 2 CAE 1 CAE 2

Neutral Interface

CAPP PP&C CAM CAQ

Neutral Interface

Requirements of an Interface

• The interface must be capable of handling all manufacturing data

• There should be no information loss• The system must be efficient to be capable of

handling the realtime requirements of manufacturing

• The system should be open-ended to permit extensions or contractions

Requirements Continued

• The system should be adaptable to other standards

• The system must be independent of the computer and architecture used

• Test procedures must be provided to verify effectivety.

Interfaces

CAD/CAD CAD/CAM

Standardization Organization

National & European International ISO

IGES

PDDI

SET

VDA/FS

CAD*I

CIM-OSA

EDIF

PDES ANSI (USA)

AFNOR (France)

DIN (Germany)

ESPRIT (EEC)

ESPRIT (EEC)

Product Data Structure

STEP

( A full data model)

USA Electronics Industry ???

Evolution of Data Standards

Initial Graphics Exchange Specification (IGES)

• IGES defines neutral database in the form of a file format, which describes an IGES model of modeling data of given product

• IGES model can be interpreted by dissimilar CAD/CAM systems.

• Supports many 2D and 3D CAD entities• Has gone through several versions since 1980• Widely supported

Data Exchange using IGES

Native Database Preprocessor IGES

Archival data base

Post processor Native Database

Combined in compressed ASCII format

File structure and File format• Put IGES• Get IGES

Flag section(Optional)

Start section

Global Section

Directory Entry section

Parameters Data section

Terminate section

Testing

• Reflection Test• Transmission Test• Loopback Test

Problems with IGES

• Many incompatible “flavours”• Unreliable translation, particularly for complex

geometry• No formal information modelling basis• Insufficient support for conformance testing

PDES

• PDES is an exchange for product data in support of industrial automation.

PDES ArchitectureMechanical products

Electrical Products

AEC Products

Application N Applicati

on Layer

Generic entities

App. specific entities

Logical Layer

File format and data structure

Physical Layer

Product data exchange using PDES

Archival product data

Three layer architecture

Data exchange unitPreprocessorDiscipline model

Product data

Post processor

Product data

Discipline model