iLogic (Inventor)
Inventor's rule engine — VB.NET-based rules attached to parts, assemblies, or drawings that automate parameter changes, suppress features, drive iParts, and integrate with external data.
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Definition
iLogic rules are stored inside an Inventor file. Rules trigger on parameter changes, file open, or manual run. Rule actions include changing parameters, suppressing/activating features, replacing components, setting iProperties, reading Excel files, writing log files. The rule language is VB.NET-style with Inventor-specific APIs.
Why it matters
iLogic enables one part file to behave as a configurable product line — change a parameter and the entire part reconfigures. For machine OEMs producing configured-to-order designs, iLogic is the engine.
Common pitfalls
- Rules with infinite-loop side effects on parameter change.
- Hardcoding paths to Excel files — breaks for other users.
- Not testing iLogic rules across all expected parameter combinations — silent failures.
Rules, parameters, and triggers
iLogic embeds design logic in Inventor documents as rules written in a VB.NET-based language. Rules read and write model parameters (Length = 120), suppress features, drive iProperties, swap components, and control configurations. Rules fire on events — After Open Document, parameter change, or manual run — so a model can reconfigure itself when an input changes.
Building maintainable automation
Expose user inputs through a form so non-authors drive the model without editing code, and centralise shared logic in an external rule stored in the project so many documents reuse it. Prefer Parameter("name") and the iLogic snippet library over hard-coded strings, guard against missing references, and keep rule execution order explicit to avoid circular triggering.
References
Primary and vendor documentation used while writing this page (external links, not republished):
Inventor Ecosystem Context
This concept is a core structural element of the Inventor drafting and engineering environment developed by Autodesk. Autodesk's Windows-native parametric MCAD — strong on large mechanical assemblies, sheet metal, frame generator, and integration with Autodesk Vault and Revit.
Relevant Inventor FAQs
❓ What's the difference between Inventor and Fusion 360?
Inventor is Windows-only desktop, file-based, deep MCAD with Vault integration. Fusion 360 is cross-platform (Win/Mac), cloud-data, broader scope (CAM, electronics, generative design), simpler assemblies. Inventor for established mechanical engineering teams; Fusion 360 for makers, small teams, integrated CAM workflows.
❓ Can Inventor open SOLIDWORKS files?
Indirectly. Inventor doesn't natively read .sldprt/.sldasm; export from SOLIDWORKS to STEP or Parasolid, then open in Inventor. Features import as static geometry without parametric history.
❓ What's in the Product Design & Manufacturing Collection?
Inventor, AutoCAD, AutoCAD Mechanical, Inventor Nastran (FEA), Inventor Tolerance Analysis, Factory Design Utilities, Inventor CAM, Vault Basic, ReCap Pro, and Fusion 360 (selected modules). Most production Inventor users are on PDMC rather than standalone Inventor.
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Autodesk Inventor 2025 | Basics For Beginners | Step-by-Step
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