STEP is the most neutral format used to exchange data between CAD systems. STEP (STandard for the Exchange of Product model data) is an ISO standard (iso 10303) to represent 3D objects and related information. The development of STEP started in 1984 as a successor of IGES, SET and VDA-FS. The initial plan was to get a single edition but because of the complexity, the standard had to be broken into separate parts (APxxx). Today AP203 is still one of the most important parts of STEP and is supported by many CAD systems for import and export. In a second phase the capabilities of STEP got widely extended, primarily for the design of products in the aerospace, automotive, electrical, electronic, and other industries. This phase ended in 2002 with the second major release, including the STEP parts AP 202, AP 209, AP 210, AP 212, AP 214, AP 224, AP 225, AP 227, AP 232. In mid 2010 the development of the new major AP 242 was initiated. This edition will replace the most successful STEP AP203, AP214 and other APs in the mechanical design area. In particular it will contain major updates in the area of Geometric dimensioning and tolerancing, Kinematics, and Tessellation. CAD Interop distributes several solutions to view, exchange and validate STEP files. We offer custom solution to meet every unique need:

Système CAOKernelImport (1)Export (1)
 CADDS  Propriétaire IGES*, DXF IGES*, DXF
 I-DEAS  Propriétaire IGES, STEP*, Parasolid IGES, STEP*, Parasolid, JT
 Catia V4  Propriétaire IGES, DXF, STEP* IGES, DXF, STEP*
 Catia V5  Propriétaire IGES, DXF, DWG, STEP* IGES, DXF, DWG, STEP*
 UG NX  Parasolid IGES, DXF, DWG, STEP, JT*, Parasolid, STL IGES, DXF, DWG, STEP, JT*, Parasolid, STL
 Pro/Engineer Wildfire  Granite IGES, DXF, DWG, STEP, ACIS, Parasolid, Granite*, STL, VDA IGES, DXF, DWG, STEP, PDF, ACIS, Parasolid, Granite*, STL, VDA
 Pro/Engineer Creo  CreoDirect IGES, DXF, DWG, STEP*, ACIS, Parasolid, Granite, STL, VDA IGES, DXF, DWG, STEP*, PDF, ACIS, Parasolid, Granite, STL, VDA
 SolidWorks  Parasolid IGES, DXF, DWG, STEP, ACIS, STL, Parasolid*, PDF, VDA IGES, DXF, DWG, STEP, ACIS, STL, Parasolid*, PDF, VDA
 Inventor  ACIS IGES, DXF, DWG, STEP, ACIS*, STL, Parasolid, Granite, PDF, VDA IGES, DXF, DWG, STEP, ACIS*, STL, Parasolid, Granite, PDF, VDA
 Solid Edge  Parasolid IGES, DXF, DWG, STEP, JT, ACIS, Parasolid, STL IGES, DXF, DWG, STEP, JT, ACIS, Parasolid*, STL, PDF

(*) recommended neutral file format for 3D geometry interoperability
(1) Only major neutral file formats are listed. Some CAD systems may have some limitations with specific format.

The standard STEP AP 242 (ISO 10303 AP242) “Managed model based 3D engineering" is the merging of  2 ISO standards:

  • Aerospace's STEP AP203 "Configuration controlled 3D design"
  • and Automotive's STEP AP214 "Core data for automotive mechanical design processes"
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CSG Model

Constructive solid geometry (CSG) is a modeling technique used in CAD systems to create a complex geometry by combining parametric features and Boolean operations. CSG presents a solid or surface that appears visually complex, but is actually little more than cleverly combined or uncombined objects (primitives, extrusion, revolution, sweep, filet, chamfer, shaft, ...). The CAD system usually translates a CSG modeling into a BREP geometrical representation during an update of the construction tree. Therefore, it is necessary to have performed an error-free update before exporting in a neutral format to ensure that the BREP representation conforms to the design intent.



B-REP modelBoundary Representation is a method for representing shapes using the limits. it is often abbreviated as B-Rep or BREP in CAD modeling. A solid is represented as a collection of connected surface elements, the boundary between solid and non-solid. Boundary representation models are composed of two parts: topology (faces, edges and vertices) and geometry (surfaces, curves and points). An edge is a bounded piece of a curve and a vertex lies at a point. A face is a bounded portion of a surface. These geometry is commonly called "precise geometry".
Manifold solids have the property that, at every point on the boundary, a small enough sphere around the point is divided into two pieces, one inside and one outside the object. Non-manifold models break this rule.


Faceted modelTessellation is a triangular approximation to represent precise geometry in a light representation. SAG parameter is set to control the approximation by defining the maximum distance between the triangle and the surface.


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The CAx Implementor Forum (CAx-IF) is a group of software developers and vendors working on STEP ISO 10303. ITI Transcandata is an active CAD-IF participant since 1999.

Each participant translates a reference set of CAD models into STEP Part 21 file format. The STEP file is checked to ensure that it is syntactically, structurally, and semantically, correct. The other CAx-IF participants download each STEP file and translate it into their native system and run various diagnostics to check the semantic validity and quality of the information exchanged.

CADfix capabilities regarding STEP support with last in production release are available on the following table

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