presentation developed by Dr Ian Campbell Loughborough Design School

1. Data Exchange Between
CAD/CAM Systems

2. • Design projects require data to be shared between
suppliers
• Different companies often used different CAD systems
• All CAD systems have their own database formats
• They are mostly proprietary and often confidential
• Data is stored in different ways e.g. 1.0,2.0,3.0 or
X1.0,Y2.0,Z3.0, etc.
• Data conversion between systems becomes necessary
Why do we need Data Exchange?

3. Number of Direct translators = 2 (N-1)
Alternative approaches
System A
System DSystem C
System B
Future System

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Alternative approaches
System A
System DSystem C
System B
Future System

5. • IGES (Initial Graphics Exchange Specification)
•1980 US NIST, National Institute of
Standards and Technology
• DXF
• VDA – German Automotive Industry
• SET – Airbus
• PDES – American fore-runner of STEP
• STEP
• STL
• VRML
Data Exchange Formats

6. 3D - IGES
• The Initial Graphic Exchange Specification
(IGES) format, is the most used neutral
format to transfer data between
heterogeneous CAD systems.
• Users can perform bi-directional data
exchange between dissimilar systems with
direct and automated access to IGES files.

7. IGES file structure
• Start section
– Comment, filename, data name, etc
• Global section
– System environment information
• Directory Entry section
– Data index and data attribution
• Parameter Data Section
– Real data value(coordinate, parameter value)
• Terminate Section

8. 2D - DXF/DWG
• DXF/DWG : DXF formats were
developed by AutoDesk.
• After creating drawings, designers can
export data in DXF/DWG formatted files
and import the 2D geometric data
contained in a DXF/DWG file into other
drawing tools.

9. DXF File Structure
• Header Section
• Tables Section
• Block Section
• Entities Section

10. STL
• STL format was developed by 3D Systems as
a neutral format to input geometric data into
their 3D printing systems
• It represents the geometry as a series of
triangular facets
• It is now being used for other purposes
besides 3D printing
• It is simple to create but has little overall
structure

11. VRML
• VRML (Virtual Reality Modeling
Language) format is also a facetted
format
• It can represents other aspects besides
geometry, e.g. colour
• It is widely used for graphics
visualisation purposes

12. STEP
• STEP AP203 / AP214 format (Standard for
the Exchange of Product model data)
• It supports geometry and assembly structures
and handles topology (shells, solids) on
export and import.
• STEP files are human readable
• Other STEP APs are available, e.g.
electronics data

13. • Who is the data for?
• What level of data is required (2D/3D, solids/surfaces)?
• What will the data be used for?
• How long will the data be kept?
Questions to Ask about Data Exchange