Standards for CAD Data Exchange

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

Product Design (CAD) Engineering and Analysis (CAE) Customer Requirements Product Databases Manufacturing Databases Materials Planning Procurement Installation and Distribution Fabrication, Assembly & Test Operations Product Information Management Product Design Manufacturing Engineering Supply Management Customer Suppliers Marketing Process Planning Neutral I/F Product Data Management CAD data is used throughout the organization

Typical Situation Major company uses CATIA Major supplier uses I-DEAS Small supplier uses AutoCAD Small supplier uses 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-DEASUnigraphics 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 CAPPPP&CCAM 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) 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 Architecture Mechanical 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 unit Preprocessor Discipli ne model Product data Post processor Product data Discipline model