Model-Based Definition bundles all product information

Everyone is talking about digital continuity, but how exactly can this challenge be put into practice?

This question is posed, for example, when handling 3D models, which are a fundamental component of the construction process and digitally created with CAD authoring systems. But often not all technical details are yet stored in the model. Today, many companies still use 2D drawings and separate documents with manufacturing information. Quality demands often cannot be met and errors are detected late, which leads to high costs, because of the media break between digital model and paper-based drawing.

In the context of industry 4.0, it is now about making increasing use of digital formats with all associated product data. All product information should also be available to downstream processes interdisciplinary. Changes that would have to be completely recreated with manual effort in the case of paper-based drawings can be implemented digitally without any problems.

And, to optimize product development and save time in the development process moreover, start models and construction guidelines are used. This ensures existing know-how in the company and simplifies the induction of new employees. Changes and variants are also realised faster and process-relevant information is automatically provided to subsequent processes.

Following we have compiled the most important questions and answers from practice concerning digital 3D drawings, start models and construction guidelines for you.


Because all product descriptive information is stored in the 3d model, redundancies and inconsistencies are avoided (single-source-of-truth), which means fewer errors and higher quality.

Information on the drawing is not computer-readable and the information is not linked to specific features in the 3d model.

Only in this way all necessary information can be made available digitally to the subsequent processes so that they can be processed further automatically. So for example, the information about a surface property is directly linked to the respective 3d object and can be automatically taken into account when editing the object.

For this there are tools within authoring systems such as ft&a in catia. Based on these tools, a method must be defined for transferring this information into the 3d model.

Many oems have integrated pmi information into the 3d model since long. This procedure enables downstream processes to access automatically to the product information.

First you should make sure that the cad data is based on a uniform data model. Furthermore, it must be ensured that this data model is used by the employees in the intended manner.

...drawings today, can easily get the necessary information from the 3d data in the future?

This is certainly one of the biggest challenges. The first step is to determine who is working with which data in the process and when. Then it has to be determined in which format and to what extent the data will be passed best to the respective process step in the future.

An important prerequisite is a clear data structure. This is realized in the cad authoring system by a start model. It is further important to find a suitable data exchange format that can transfer all required information between the processes involved.

A start model describes a kind of table of contents of the product features with pre-defined structures, settings and geometry elements. This ensures that follow-up processes can always find the necessary information at the same place. It consists of fixed components that cannot be changed by the user as well as variable components. Important process-relevant settings are deposited as control parameters.

A design guideline describes the structured process from the first layout to the approval of the product to be manufactured. Among other things, it is binding prescribed who has to store which information where and when in the cad model. This ensures that every participant is informed of the necessary procedure. Internally existing know-how is maintained and the induction of new employees is facilitated.

By using an automatic test tool, it can be ensured that these instructions will be followed.

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