A part designed in NX with individual measurements notated, as model based definition.

Geometric dimensioning and tolerancing

Model-based definition

Model-based definition (MBD) enables a complete digital definition of a product within a 3D model. Compared to drawing-centric workflows, NX reduces the time spent on engineering documentation and drives downstream tools for validation and manufacturing.

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Realize a product's complete digital twin with MBD

Addressing product complexity and accelerating product development processes are made easy with model-based definition.

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Replace the universal 2D drawing

Eliminate the need for 2D drawings while also ensuring the final product complies with its engineering specifications. With NX, product teams can capture and share engineering requirements within the 3D model, thereby permitting full use of the design intent.

People are familiar with 2D drawings and use them to define a finished product. 2D drawings contain standard symbology that is universally understood and interpreted. However, in some cases, the existence of multiple, redundant data required to define a manufactured part can lead to deviations in the final 3D form. Interpretation errors, duplication errors or revision inconsistencies can contribute to costly mistakes that quickly translate into lower quality and productivity.

Geometric dimensioning and tolerancing (GDT) is an essential component of complete part definition. It affects most areas of product realization including design, tooling, production and inspection. Apply GDT to 2D part views and 3D models respectively. Use NX CAD to apply GDT symbols to 2D part views and 3D models.

The use of 2D drawings to communicate downstream production requirements adds an unnecessary burden to the product development cycle. A simple change in the product definition requires updated 3D digital data and necessitates numerous engineering changes to all 2D documentation associated with the product. Since it takes time to maintain this documentation, the lifecycle for implementing a product change grows with the extent of its associated 2D data.

A composite image of a component with 3D Dimensions (PMI) layered over & 2D Drawing for comparison.

Leverage legacy data

Begin every project with a clean sheet. NX offers Convert to PMI, a function that automatically converts drawing views and objects to corresponding model views and product manufacturing information (PMI) objects. This saves tremendous amounts of time when leveraging legacy data. You can use legacy drawings to add intelligence to 3D models quickly and easily.

The tool is highly customizable with options to convert entire drawings or individual sheets, views and annotation objects. It provides a conversion report with detailed summary results. It also enables support for processes based on 3D models with much lower cost and higher quality of data.

Model based definition within NX CAD on a router box design

Productivity improvement with model-based definition

Learn how MBD improves business efficiency in the manufacturing industry.

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Case study


Mechanical design specialists develop a Stirling engine from scratch in few months with NX.
Case Study

Mechanical design specialists develop a Stirling engine from scratch in a few months with NX


行业:航空航天及国防行业, 船舶行业, 工业机械行业

位置:Trieste, Italy

Siemens 软件:NX