IGES Export Settings tips - Any CAD System

Technote 82
Product: Advanced Milling, FreeForm Machining
Date: 06/94
Version: Up to v11.5

Problem:
General information about working with IGES files.

Steps in Conversion Process:

1. Pre-processing on the CAD System
   • Explode subfigures
   • Convert offset surfaces to spline surfaces
   • Select only the surfaces that need to be exported to SmartCAM
2. Export to IGES from CAD System
   • Convert surfaces to IGES entity 128 spline surface types
   • Convert spline curves as IGES entity 126 (B-spline)
   • Output XYZ data (model space curves) in addition to UV data (parameter space curves) for trimmed surfaces
   • Export all surfaces as IGES entities 142/144 (Curve on Parametric Surface/Trimmed Surface), as the first preference
   • Export all surfaces as IGES entities 141/143 (Boundary Entity/Bounded Surface), as the second preference
3. Import into SmartCAM
   • First Preference for Import Settings:

     U, V Count = 1, 1
     Tolerance = .01 inches
     

   • Second Preference for Import Settings:

     U, V Count = 0, 0
     Tolerance = 0.1 inches
     This would be faster, but would not be able to tell difference between surface patches and so surface picking may be difficult.

   • Third Preference for Import Settings:

     U, V Count = 3, 3
     Tolerance = .005 inches
     This would be slower, but more descriptive on complex surfaces.

   • Create a log file. Use the log file to review import error messages.
4. Post-Processing in SmartCAM
   • Checking and Debugging the Model:
     • Use Dynamic View to review entire model, see that surfaces look connected or look like the engineering drawing.
     • Use View - Render Image for a shaded view of model, to visually inspect import.
     • Review import log file for errors or lost surfaces.
     • Review release notes for known limitations in IGES transfers.
   • Test the surface:
     • Property Chg - Surfaces to change the number of display grid curves and see if surface still looks good.
     • Use Render Image to visually inspect surfaces.
     • Use Surface Machine - Straight and verify toolpath follows the surface.
   • Replace bad surfaces with new ones or edit surfaces:
     • Mesh Edit - Generate Mesh to get a meach that covers the surface.
     • Mesh Edit - Extract - Trimming Curves to get wireframe elements from boundary edges.
     • Group Trim the mesh back to the trimming curves.
     • Create - Surface - From Mesh to create the new surface.
   • Review computer hardware setup, in case of a crash or out of memory error. Does computer meet minimum RAM and virtual memory requirements?