IGES File Format

Definition & Context

IGES (Initial Graphics Exchange Specification) is a vendor-neutral file format for exchanging CAD geometry between different systems. It predates STEP and is now considered legacy, but is still encountered with older data or tools that export nothing else. IGES carries wireframe, trimmed NURBS surfaces, and — through manifold B-Rep entities — limited solid data.

Because IGES stores geometry only (no features, history, materials, or assembly structure), an IGES import arrives as static “dumb” surfaces or bodies. Virtually every CAD system (SOLIDWORKS, NX, CATIA, Inventor, Rhino, Fusion) reads and writes it through its import/export dialog, where you choose to bring data in as solids, surfaces, or curves and set a stitching tolerance.

Why It Matters

IGES matters mainly as a fallback: when a supplier or legacy system can only provide IGES, knowing its limits (surface gaps, dropped solids, no PMI) tells you what repair to expect after import. For new work, STEP AP242 is almost always the better neutral choice.

Knowing when not to use IGES is as important as knowing how — for solid exchange it frequently drops features and leaves un-stitched surfaces that must be healed before downstream CAM or analysis.

Best Practices

• Prefer STEP AP242 for new solid/PMI exchange; reserve IGES for tools that support nothing else
• On export, use trimmed-surface representation and set the tolerance to match the receiving system
• On import, enable stitch / “try forming solid” and check for naked edges before modeling on the result
• Send units and tolerance alongside the file, since IGES carries no reliable metadata

Common Pitfalls

• Expecting solids to survive — IGES often imports as disconnected surfaces that need stitching
• Unit mismatches (mm vs inch) silently scaling the model; confirm units on both ends
• Tolerance too loose leaves boundary gaps; too tight bloats the file and slows import
• Assuming features or parameters transfer — they do not; the import is static geometry

References & Further Reading

• https://help.solidworks.com/

Related Concepts

Explore more Multi-platform topics in our Multi-platform knowledge base, or browse the full terminology index.

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Enterprise Production Implementation & GstarCAD 2027 Workflow

• Database Serialization & Binary Fidelity: Ensure all entities and symbol table records associated with IGES File Format are authored on standardized ISO 13567 layers rather than Layer 0 or Defpoints, and verify lossless round-trip persistence in native DWG (AC1032) format.