CAD File Formats

Complete Guide to Native and Neutral Exchange Formats

Native Formats

NAT
Native CAD Formats
Native formats are proprietary file formats specific to particular CAD software systems. Each CAD application creates and works best with its own native format, preserving all design intent, parametric features, and metadata.
  • .SLDPRT/.SLDASM - SolidWorks parts and assemblies
  • .CATPart/.CATProduct - CATIA V5/V6 components
  • .IPT/.IAM - Autodesk Inventor parts and assemblies
  • .PRT - Siemens NX, PTC Creo native files
  • .DWG/.DXF - AutoCAD drawing formats

✓ Advantages

  • Complete preservation of design intent and parametric history
  • Full access to all software-specific features and tools
  • Optimal performance and file size efficiency
  • Perfect compatibility within the same software ecosystem
  • Maintains assembly relationships and constraints

✗ Disadvantages

  • Limited cross-platform compatibility
  • Requires specific software licenses to access
  • Version compatibility issues between software releases
  • Vendor lock-in concerns for long-term data accessibility
  • Collaboration challenges in multi-CAD environments

Neutral Exchange Formats

NEU
Neutral Exchange Formats
Neutral formats are standardized file formats designed for data exchange between different CAD systems. They serve as a universal language for sharing 3D models, drawings, and technical data across diverse software platforms.

STEP

.step .stp

Standard for Exchange of Product Data - ISO 10303 international standard. Most widely used for precise 3D geometry exchange.

  • AP203: Configuration controlled design
  • AP214: Automotive design processes
  • AP242: Managed model-based 3D engineering

IGES

.igs .iges

Initial Graphics Exchange Specification - One of the earliest CAD exchange standards, still widely supported for legacy compatibility.

  • NURBS surfaces and curves support
  • 2D drafting entity exchange
  • Widely supported across platforms

STL

.stl

Stereolithography - De facto standard for 3D printing, representing surfaces as triangulated meshes.

  • ASCII and binary formats available
  • Simple triangular facet representation
  • Universal 3D printing compatibility

OBJ

.obj

Wavefront OBJ - Popular format for 3D graphics and visualization, supports geometry and material definitions.

  • Polygon mesh representation
  • Material and texture mapping support
  • Wide graphics software compatibility

Parasolid

.x_t .x_b

Siemens Parasolid Kernel - Precise geometric modeling kernel format used by many CAD systems.

  • Text (.x_t) and binary (.x_b) formats
  • High-precision geometric data
  • Native to many CAD applications

ACIS

.sat

Spatial ACIS Kernel - 3D geometric modeling kernel with precise solid modeling capabilities.

  • ASCII text format (.sat)
  • Solid and surface modeling
  • Used by various CAD platforms

3D PDF

.pdf

3D Portable Document Format - Adobe's extension allowing 3D model embedding in PDF documents for universal viewing.

  • No CAD software required for viewing
  • Interactive 3D manipulation
  • Cross-platform accessibility

JT

.jt

Jupiter Tessellation - Siemens' lightweight format for large assembly visualization and collaboration.

  • Lightweight visualization
  • Large assembly performance
  • Multi-level detail support

✓ Advantages of Neutral Formats

  • Universal cross-platform compatibility
  • Vendor-independent data preservation
  • Standardized data exchange protocols
  • Long-term data accessibility assurance
  • Facilitates multi-CAD collaborative workflows
  • Industry-standard compliance and certification

✗ Disadvantages of Neutral Formats

  • Loss of parametric design history
  • Potential geometry translation errors
  • Larger file sizes compared to native formats
  • Limited software-specific feature support
  • May require data validation after translation
  • Assembly intelligence often not preserved

Choose the Right Format for Your Workflow

Understanding CAD file formats is crucial for effective design collaboration and data management. Select native formats for design work and neutral formats for universal exchange.

Learn More About CAD Standards