NX MBD with AI

NX MBD with AI: Associative PMI on the 3D Model, Placed in Your Live Session

Model-based definition in NX (NX MBD) stands or falls with the PMI on the model. An AI agent can place part of it today: dimensions that NX measures itself, attached to real faces and shown in the right model views. Datums, GD&T and tolerances stay with your engineers, and we say so before a project starts.

This page is about where AI fits into NX MBD and what an agent can put on the model in a live session today. Whether the model or the drawing is your master is a separate decision, covered in MBD or 2D drawing as the master. Preparing the routine PMI of whole part families from rules is Rule-Based PMI Creation; authoring PMI for one part in a conversation is the MBD & PMI Authoring Assistant; checking PMI before release is MBD/PMI compliance automation. The agent-based pages belong to our family of NX AI assistants and chatbots.

NX MBD with AI: the short version

• What NX MBD is: PMI on the 3D model as semantic objects, organized in model views, so the model is the reference for manufacturing and inspection.
• What the agent places today: associative linear and radial PMI dimensions on annotation planes the tool sets explicitly, PMI shown in the right model views, and existing PMI moved or re-attached. Hole and thread callouts are built and in testing.
• What stays with engineers: datum schemes, feature control frames and tolerances. Our 3D PMI tools have no tolerance input, so the AI cannot invent one.
• Where it fits next to NX: the MBD Logic Editor for rules you can write as logic, PMI Advisor and Check-Mate for checking, the agent for requests no rule covers yet.
• What it is not: a 2D-to-3D migration service, a drawing generator or an automatic release.

What NX MBD puts on the model

In NX, PMI is created on the 3D part in the Modeling or Gateway application. Each PMI object exists twice: as a semantic object, listed under the PMI node of the MBD Navigator, and as a display instance in a model view. The semantic object is what downstream systems read; the display decides who sees it in which view.

The PMI types NX offers include dimensions (rapid, linear, radial, angular, chamfer, thickness, arc length and ordinate), datum feature symbols, datum targets, feature control frames, notes, symbols and PMI section views. PMI hole and thread callouts are associated with the hole feature rather than with its faces. For the hand-over, NX maps semantic PMI to STEP AP242, so a CMM program or a supplier whose software reads AP242 gets the same definition. A complete MBD model is a lot of objects, placed on the right faces, in the right views, to a standard. That volume is where automation pays.

NX’s own MBD tools, and where an AI agent fits

Siemens NX already automates parts of MBD. Before an agent is added, it is worth knowing which job each tool does best.

Our rule of thumb: if a rule fits completely into the Logic Editor, write it there. A language model adds nothing to a rule that already runs as logic, and we build rule-based PMI too. The agent earns its place where rules run out: an annotation an engineer asks for in a sentence, a part outside the families your rules cover, or the gap between the dimensions a rule creates and the complete set the model needs. Why the guideline matters more than the model is covered in what worked with AI-generated PMI in NX.

What the agent puts on the model today

The PMI catalog is smaller than the modeling catalog, on purpose. Every type in it is created through NX’s own PMI builders; the status column says which ones are verified in a running session.

The reference test continues the session in which the AI modeled a block with two holes, a blend and a chamfer, described on our page about AI CAD modeling in Siemens NX. On the finished block the agent then placed linear and radial PMI: measured by NX, attached to the faces, listed in the MBD Navigator like PMI an engineer creates in the PMI tab.

How an AI PMI request runs in NX

Take a request on an open part: dimension the overall length and the blend radius, and show them in the main view. The engineer asks once; the work follows a fixed pattern.

1. Read what exists. The agent lists the PMI already on the part, so it can add what is missing instead of duplicating it.
2. Pick the geometry. The agent reads the faces and edges of the part and picks the ones it needs.
3. Set the plane. The tool sets the annotation plane explicitly instead of inheriting whatever view is current.
4. Create. NX’s PMI builder creates the dimension, and the value comes from NX.
5. Show. The PMI is assigned to the model views your guideline defines.
6. Check. The engineer, PMI Advisor or our compliance checks review the result before anything is released.

Where AI-placed PMI goes wrong, and what the tools do about it

In our builds, creating a PMI object was rarely the problem. Placing it correctly was.

That does not show in a demo on a perfect part. It is why we test every PMI tool on parts that look like yours before it goes live, and why the engineer reviews what the agent placed.

Datums, tolerances and release stay with engineers

A datum scheme encodes how the part is located, measured and assembled; a tolerance encodes what the function needs. Neither can be read off the geometry, and neither should come from a language model guessing. With our current tools the agent cannot set tolerances on 3D PMI at all, and datum features and feature control frames on the model remain the engineer’s work.

Where your standard already says what goes where, rules can prepare part of it: rule-based PMI creation prepares datum schemes from a family strategy and standard callouts, and the engineer completes and releases them. Release itself is a person’s decision, recorded in your PLM. Checking before release is a job for PMI Advisor, Check-Mate or our MBD/PMI compliance automation, not for the agent that placed the PMI.

NX MBD with AI and its neighbors on this site

MBD touches several of our pages. They cover different steps of the same process, and most projects use more than one of them.

What NX MBD with AI does not do

An agent takes repetitive placement off the designer’s desk. It does not take over the engineering decisions behind the PMI, and it does not remove the limits of NX or of its API.

For checks that run while a designer works, rather than on request, the event-driven live model check assistant is the better pattern. Two projects where rule-based PMI automation already runs in production, without a language model, are our automotive PMI automation case study and the automated PMI placement and numbering case study.

Deployment, data and hosting options

The PMI tools run in the live NX session, and NX stays usable between calls. Our current PMI tools are built and tested on NX 2606.

Part files stay in your network. What reaches an AI model is what a tool returns: face types, positions, the list of existing PMI and, where you allow it, an image of the part in a standard view. Where the models run is decided per project: through Anthropic, through cloud providers with EU regions, in Germany or on premises. Which PMI tasks a smaller local model handles well is something we test on your parts before we promise it.

How we introduce AI into your NX MBD

The order matters more than the model. A guideline that exists only in the heads of two senior designers is the first thing to fix, with or without AI.

1. Guideline first. Which PMI each feature type gets, which model views exist, which standard applies, ISO GPS or ASME Y14.5. If it is not written down yet, we derive it with you from good reference models.
2. Split the work. What goes into Logic Editor rules, what into typed PMI tools for the agent, and what stays manual.
3. Read tools first. The agent lists existing PMI and geometry before it places anything, so the team sees it understand their parts.
4. PMI tools on your parts. Each tool is tested on parts that look like yours.
5. Checks in place. PMI Advisor or Check-Mate rules are set up, so every result is checked the same way, whoever placed it.
6. Pilot. One part family and a small group of designers, measured on PMI placed, corrected and deleted.
7. Rollout. More PMI types and more families, with recurring requests turned into rules.

Start with one part family in your NX

We do not start with every PMI type at once. We start with one part family, the PMI your designers place by hand on every part of it, and your guideline as the reference.