Model-Based Definition (MBD)

Model-Based Definition (MBD) is the logical capability of designating the 3D CAD model — with embedded PMI, GD&T, and metadata — as the legal authority for design specification, eliminating or relegating 2D drawings to a derived role. ASME Y14.41 and ISO 16792 codify the practice.

What it covers

• Authoritative 3D dataset with semantic PMI, GD&T, and material data.
• 3D PDF and JT as consumption-side derivatives for non-CAD readers.
• Drawing-as-derived view policies in the PDM/PLM workflow.
• Supplier and inspection workflows that consume MBD without 2D drawings.
• Long-term archival in STEP AP242 to outlive any single CAD format.

Relationships (see sidebar)

• Supports the Detailed Design, Supplier Development, and CAM Manufacturing Planning processes.
• Implemented by CAD systems including Siemens NX, Dassault CATIA, PTC Creo, SolidWorks, and Autodesk Inventor.
• Composed of PMI Annotations plus GD&T; archived via STEP AP242 and JT visualization.