What is CAD Interoperability?

What is CAD Interoperability?

CAD interoperability is the ability to move product geometry and associated data between different CAD authoring systems in a way that preserves sufficient fidelity for downstream use. That qualifier — "sufficient fidelity for downstream use" — is important because interoperability is not binary. A translated model that looks correct in a viewer may be unsuitable for manufacturing simulation. A model that works for toolpath generation may have lost PMI (Product and Manufacturing Information) annotations that a quality inspector needs. What counts as adequate translation depends on what the receiving party needs to do with the data.

The root cause of interoperability difficulty is geometric kernels. A geometric kernel is the mathematical engine that a CAD system uses to represent solid geometry — the algorithms that define surfaces, compute intersections, and validate that a solid is topologically closed. Major CAD systems use different kernels: PTC Creo uses Granite; CATIA V5/V6 uses the CGM (Convergence Geometric Modeler) kernel developed by Dassault; SolidWorks, Solid Edge, and many others license Parasolid from Siemens; AutoCAD and Inventor use ACIS. These kernels represent the same physical shape using different mathematical constructs, different tolerance schemes, and different rules about what constitutes a valid surface.

When a CATIA model is translated to SolidWorks, the translation software must convert the CGM representation to Parasolid. For simple geometry — prismatic shapes, standard fillets, basic extrusions — this translation is generally reliable. For complex geometry — tight fillets in tight spaces, complex surface blends on Class A automotive surfaces, near-tangent edges that are mathematically borderline in one kernel but outside tolerance in another — translation failures are common. The result may be a model with missing faces, with topology errors, or with geometry that passes a visual check but fails a manufacturing tolerance check.

Why CAD Interoperability Matters in PLM

The practical business context that makes CAD interoperability a PLM problem is supply chain diversity. An OEM may standardize on one CAD system for its internal engineering organization. Its 200 direct suppliers may use 15 different CAD systems. Its sub-tier suppliers add another 25. The OEM cannot mandate that every supplier in its supply chain adopt the same CAD system — the capital cost, training cost, and disruption would be prohibitive, and most suppliers serve multiple customers who have different CAD requirements.

PLM systems must therefore manage product geometry that arrives in multiple native formats and exchange it with suppliers in formats they can use. This creates a multi-layer interoperability problem. Inbound: how does the OEM receive supplier geometry, validate it, and store it in PLM alongside native designs? Outbound: how does the OEM send design intent to suppliers in a format they can use to design mating components and manufacturing tooling? And across the supply chain: how do tier-1 suppliers pass geometry down to tier-2 and tier-3 suppliers who may use completely different systems?

The neutral format ecosystem exists to address this. STEP is the engineering exchange standard — when two organizations need to exchange precise, editable geometry with full manufacturing information, STEP AP242 is the current best practice. JT is the visualization standard — when stakeholders need to view and inspect 3D geometry without editing it, JT provides a compact, fast-loading representation. The critical governance issue in PLM is maintaining clarity about which format is authoritative. A common failure mode is organizations accepting JT as a delivery format for supplier design data and then discovering, when they need to generate manufacturing tooling, that the JT geometry is insufficiently precise for that purpose.

Common Use Cases

• OEM-supplier design collaboration: An aerospace OEM sends native CATIA V5 design geometry of a structural assembly to a machined-parts supplier. The supplier opens it in their Creo environment using STEP AP242 exchange, designs their machined component to mate with the reference geometry, and returns their design in STEP format for integration into the OEM's PLM system. The PLM system stores both the native and the STEP versions with clear metadata identifying the authoritative format.
• Digital mockup and design review: A vehicle OEM assembles a complete digital mockup of a new vehicle program in JT format, aggregating lightweight representations from hundreds of suppliers. Design review teams and manufacturing planners use the JT mockup for interference checking and assembly sequence planning without needing access to native CAD data from suppliers who consider their geometry proprietary.
• Cloud PLM migration: A manufacturer moving from an on-premises PLM with a legacy CATIA V5 archive to a cloud platform evaluates which models need to be translated to neutral STEP format for long-term accessibility and which can remain in their native format, given that the cloud platform may not natively host the same CAD authoring environment as the original system.

Related Concepts

• What is PLM? — CAD interoperability is managed within PLM as part of the product data management function
• What is the Digital Thread? — the digital thread requires that geometry and associated metadata flow across system boundaries without loss of traceability
• Cloud PLM vs On-Premises PLM — cloud PLM deployments have specific CAD data hosting and translation implications

Frequently Asked Questions

Why is CAD interoperability so difficult?

CAD interoperability is difficult primarily because major CAD systems use different geometric kernels — the mathematical engines that define how geometry is represented and calculated. PTC Creo uses Granite. CATIA uses CGM. SolidWorks and many others use Parasolid or ACIS. These kernels represent the same physical shape using different mathematical constructs and tolerancing schemes. When translating between them, complex geometry — tight fillets, complex surface blends, near-tangent edges — often fails to translate cleanly. The translation software must make approximating decisions, and those approximations can create geometry that looks correct visually but has problems that only manifest when the model is used for manufacturing simulation or toolpath generation.

What is STEP and why does it matter for PLM?

STEP (Standard for the Exchange of Product Data, ISO 10303) is the primary international standard for exchanging CAD and product data between different systems. It defines a neutral file format that captures geometry, assembly structure, and product properties in a way that any compliant system can read. STEP AP203 and AP214 cover 3D geometry; STEP AP242 adds PMI (dimensions, tolerances, and annotations embedded in the 3D model) and is the current best practice for complete 3D product data exchange. STEP matters for PLM because it is the standard that enables product data to move between the OEM's PLM system and supplier CAD systems without requiring the supplier to use the same software.

What is JT format and how is it used in PLM?

JT (Jupiter Tessellation, ISO 14306) is a lightweight 3D format developed by Siemens that stores a highly compressed, tessellated (mesh-based) representation of 3D geometry. It is optimized for fast loading, large assembly visualization, and distribution to stakeholders who need to view geometry without full CAD software. JT is widely used in automotive and aerospace for digital mockup and supply chain communication. Critically, JT is a visualization format, not a design exchange format — it does not contain the precise mathematical geometry of the original model and cannot be used as the basis for manufacturing operations like NC toolpath generation without introducing approximation errors.