Product Structure (CATIA Assembly)

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Definition

A Product is a CATIA assembly container. It references CATParts and other CATProducts. Each reference is an instance with a position, an instance name, and possibly publications exposed to the assembly. Multi-instance support means one CATPart referenced multiple times in the Product.

Why it matters

Product structure determines BOM, assembly performance, and access control. A flat Product with 50k CATPart references is unmanageable; a deeply nested structure that matches the real manufacturing tree is.

Technical Deep Dive & Core Mechanics

Product Structure (CATIA Assembly) interacts with the assembly solver, which maintains positional relationships between components through a system of mates or constraints (coincident, concentric, distance, angle). The solver treats each mate as an equation in a nonlinear system: coincident planes produce equality constraints on normal vectors and offsets, while distance mates produce inequality or equality constraints on point-to-plane distances. The solver finds a configuration that satisfies all constraints simultaneously, or reports over-constrained/under-constrained status.

Large assemblies involving Product Structure (CATIA Assembly) stress the solver because the constraint count grows combinatorially with component count. Lightweight and simplified representations reduce the geometric data loaded into memory without removing constraint definitions, allowing the solver to position components without rendering full detail. Understanding when to use lightweight mode versus fully resolved mode for Product Structure (CATIA Assembly) is essential for maintaining interactive performance in assemblies with thousands of components.

Step-by-Step Professional Implementation

Deploying Product Structure (CATIA Assembly) in a mechanical or product-design production pipeline requires stable modeling discipline and data management:

1. Set Up the Part/Assembly Template: Start from a company-standard template that pre-configures units, material libraries, default tolerances, and drawing sheet formats. Ensure the design intent is captured through a clean feature tree from the first sketch.
2. Apply Parametric Constraints Methodically: When building Product Structure (CATIA Assembly), constrain sketches fully before extruding. Reference stable datum planes and origin geometry rather than edge references that may shift during design changes (avoiding dangling references).
3. Enrich Metadata for Manufacturing: Populate custom properties (material, finish, heat treatment, part number) in the model's iProperties, custom attributes, or parameters. These feed directly into BOMs, PDM systems, and ERP integrations.
4. Validate and Release: Run interference detection on assemblies, verify mass properties, and check for rebuild errors or suppressed features. Pass the model through your PDM/PLM check-in workflow with appropriate revision and lifecycle state updates.

Advanced Troubleshooting & Error Diagnostics

Diagnostic procedures for Product Structure (CATIA Assembly) data exchange and interoperability issues:

• STEP export loses fillet geometry: Fillets and rounds in Product Structure (CATIA Assembly) translate as faceted approximations or disappear entirely in STEP output. Resolution: Increase the STEP export precision settings (tighter chord tolerance and angle tolerance). Verify the STEP AP version—AP214 handles complex surfaces more reliably than AP203 for modern geometry. If specific fillets consistently fail, try increasing the fillet radius slightly or simplifying the adjacent face geometry.
• Configuration/variant not included in export: Only the active configuration of Product Structure (CATIA Assembly) appears in the exported file. Resolution: Most neutral formats (STEP, IGES) support only a single configuration per file. Export each required configuration separately, or use native format exchange if the receiving system supports it. For assemblies, verify that the correct configuration is active in each component before batch export.
• Thread cosmetics missing after translation: Cosmetic thread annotations on Product Structure (CATIA Assembly) don't appear in the receiving CAD system. Resolution: Cosmetic threads are annotation features, not geometric features, and don't survive neutral-format translation. Replace cosmetic threads with modeled threads (helical cut) if the receiving system needs actual thread geometry, accepting the increased file size and rebuild time.

Cross-Discipline Collaboration & Handoff

In multi-discipline product development, Product Structure (CATIA Assembly) must integrate smoothly with downstream manufacturing, simulation, and documentation workflows:

• Neutral Format Exchange: Export to STEP AP214/AP242 for maximum fidelity when sharing with partners who use different CAD platforms. Validate that feature topology, PMI (tolerances, datums, surface finish), and assembly structure survive the translation. Avoid relying on native formats for external suppliers.
• PDM/PLM Integration: Check in models through the product data management system with complete metadata (revision, lifecycle state, effectivity). Ensure that the BOM structure visible in the PLM matches the CAD assembly hierarchy, and that released parts are locked from unauthorized edits.
• Simulation and Manufacturing Handoff: Provide defeatured geometry to FEA analysts (remove cosmetic rounds, simplify internal cavities) and manufacturing-ready geometry to CAM programmers (with GD&T annotations). Coordinate on material specifications and tolerance stack-ups across the design-to-production chain.

Common pitfalls

• All parts at one level — performance and clarity suffer.
• Instances vs. references confused — editing an instance affects all instances of that CATPart.
• Mismatched display modes (visualization vs. design) — visual artefacts in large assemblies.

Relevant CATIA FAQs

Direct answers from our technical editorial desk concerning related workflows.

🎓 Recommended Practice Lessons

Step-by-step practical exercises and certification-aligned paths chosen by our editors to master this concept:

Practical Workflow Tips

Principles refined through years of parametric modeling and Product Structure (CATIA Assembly) workflows:

• Sketch fully before constraining: Draw the complete sketch profile before adding dimensions and constraints. This prevents over-constrained situations that require deleting and re-adding constraints.
• Reference origin planes, not model faces: When positioning Product Structure (CATIA Assembly) features, reference origin planes or datum planes rather than model faces. Origin planes never change topology.
• Name features in the tree: Rename each feature from its default name to a descriptive name. In complex models with 200+ features, named features save minutes per search and make design intent readable.
• Use configurations for variants: Rather than creating separate files for Product Structure (CATIA Assembly) size variants, use configurations or design tables. This keeps all variants linked to a single master definition.

Sources & further reading

• Dassault Systèmes Support & Documentation portal · Dassault Systèmes