What are the different CAD file types?

Here is a comprehensive and structured answer to that FAQ, organized to be highly scannable and SEO-friendly for a mechanical engineering audience.

When answering "What are the different CAD file types?", it helps to break the answer down into three main categories: Neutral (Universal) Formats, Native (Proprietary) Formats, and 2D/Mesh Formats.

1. Neutral (Universal) CAD Formats

Neutral file formats are vendor-agnostic, meaning they are designed to be shared across different CAD systems without requiring the original authoring software. These are essential for cross-functional collaboration, design reviews, and working with external suppliers.

  • STEP (.step, .stp): The industry standard for 3D model data exchange. STEP files represent the full 3D boundary representation (B-rep) of a model, retaining precise geometric data. They are the most reliable format for sharing solid models between different CAD platforms.
  • IGES (.iges, .igs): An older universal format primarily used for sharing surface models. While still common, it has largely been superseded by STEP for solid modeling because IGES files are more prone to translation errors or "broken" surfaces.
  • Parasolid (.x_t, .x_b): A geometric modeling kernel used by many major CAD systems (like SolidWorks and NX). Exporting to Parasolid is highly effective when transferring files between systems that share this specific kernel.
  • JT (.jt): A lightweight 3D model format widely used for visualization, collaboration, and digital mockups, particularly in the automotive and aerospace industries.

2. Native (Proprietary) CAD Formats

Native formats are created by and strictly associated with specific CAD software. They contain the complete feature tree, parametric data, and design history of the model.

  • SolidWorks: .SLDPRT (Part), .SLDASM (Assembly), .SLDDRW (Drawing)
  • Autodesk Inventor: .IPT (Part), .IAM (Assembly), .IDW (Drawing)
  • CATIA: .CATPart (Part), .CATProduct (Assembly), .CATDrawing (Drawing)
  • PTC Creo: .PRT (Part), .ASM (Assembly), .DRW (Drawing)
  • Siemens NX: .PRT (Used for both parts and assemblies)

3. 2D and Mesh Formats

These formats are either strictly two-dimensional or use a mesh of triangles to represent a 3D surface, rather than precise solid geometry.

  • DWG (.dwg) & DXF (.dxf): Originally created by Autodesk, these are the universal standards for 2D drafting, schematics, and floor plans. DXF is specifically designed for interoperability between different 2D CAD programs.
  • STL (.stl): The standard file format for 3D printing. STL files strip away parametric data and represent the model's surface as a mesh of triangles. They cannot easily be edited or reverse-engineered into solid CAD models.
  • OBJ (.obj): Similar to STL but capable of storing color and texture data. It is widely used in 3D graphics, visualization, and sometimes advanced 3D printing.

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