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CAD Model Revision Control: Mastering the Design Data Hand-off

CAD Model Revision Control: Mastering the Design Data Hand-off

Among the most critical parts of the entire manufacturing process is assuring that the correct definition of the product is shared between the product design and manufacturing teams. Mistakes in this phase have the potential for leading to expensive production delays and scrap parts that don’t get discovered until first article inspection/assembly. Despite the time and expense at stake, companies may not have effective tools in place to manage this crucial communication process.

Improving this process starts by looking at how design is recorded. Complex product design today is mostly done with 3D solid modeling. 3D models straight out of the CAD software are widely distributed across the supply chain in a variety of formats to provide a precise representation of a product or part to be manufactured. Manufacturing teams commonly start work from the original 3D models for efficient tooling design and process planning. While these models are a fantastic medium for product definition, there are some potential problems that should be mitigated.

Problem 1 - Drawings

Models are often accompanied by drawings which have been generated from the 3D model and may provide additional tolerance information and notes which form the official authority for the product definition. Since drawings are derived from the original 3D design, they are a potential source for errors in the communication process. Further, the complexity of formatting in drawings make them difficult to move between different CAD software and automate processes around them. For these reasons there is a movement among top manufacturers to stop using drawings and rely on the model-based definitions as the authority.

Problem 2 – Undocumented Changes

In an ideal world there would always be plenty of time to handle design revisions methodically and without additional distractions. Everyone intends to carefully mark all the changes in a revision. Reality and humans being what they are means that occasionally the change process will yield some intentional changes which the engineer did not document. With luck this type of mistake might get caught by a manufacturing engineer that notices the undocumented change on the new model.

Problem 3 – Unintended Changes

With design complexity comes the potential for unintended and difficult to detect changes to the model. Popular parametric solid modeling strategies allow relationships to be defined between features in the model which support quick changes across the whole design driven by adjusting parameter values. Sometimes during such edits portions of the model which were not intended to change are impacted slightly. If the designer does not notice, these head downstream toward manufacturing.

The K-Compare Solution

Kubotek’s solution for assuring changes to the product definition are understood by all stakeholders is to automate the creation of a detailed change report for each design revision directly from the CAD models. Our tool takes full advantage of the 3D model to detect all differences and to aid visualization of exactly where each change is.

If your processes are still built around drawings with revision blocks as the product definition authority you may need to continue using them for that purpose. What is important to understand is that testing the 3D models, not the drawings, is the best way to test the design change process. Creating additional documentation of the change from the models is the best way to clearly communicate to everyone involved.

Creating complete change reports reduces the risks for miscommunication in the hand-off of product definition between design and manufacturing. The world’s most complete and productive tool for doing that is K-Compare Revision.

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