Archiving CAD data is an essential aspect of managing engineering and manufacturing operations. However, archiving CAD models for long-term storage is a more significant challenge than performing regular backups. There are several factors to keep in mind to avoid ending up with a collection of inaccurate or irretrievable CAD models. In addition to the storage medium and archiving methodology, a critical consideration is the format used to archive CAD models.

Native CAD data, which is specific to a particular software application, is at risk of becoming obsolete within a few years. Copying the installation media for the applications that create the data and the operating system environment is not a reliable long-term solution. This means that CAD models need to be saved in a format that can be easily accessed in the future, even if the software that created them is no longer available.

Historically, only 2D drawing data has been archived in formats like TIFF and CGM. However, with the development of 3D data content, methods and tools have changed. Before 1980, mainly manual paper drawings and microfilm were used. Between 1980 and 1995, mainly 2D CAD drawings and a minor number of manual paper drawings were used. Additionally, 3D surface CAD design was introduced. As from 1995-2006, the usage of 3D solid and assembly CAD design generated 2D drawings from 3D master models. Afterward, the usage of 3D solid and assemblies with extended GD&T design information might be implemented.

Today, neutral formats such as STEP and JT are considered the safest formats for long-term storage. These formats can be read by multiple CAD software applications and are designed to be future-proof. However, choosing a format is not enough. Automated validation and checking procedures need to be introduced to prevent the storage of inaccurate, corrupt, or invalid legacy data.

When archiving CAD models for long-term storage, it's important to keep in mind that the archival process is not a one-time event. The data needs to be reviewed and updated regularly to ensure that it remains accessible and accurate. Additionally, archiving CAD data in a cloud-based environment can provide additional flexibility and accessibility, enabling easy access to CAD models from anywhere and at any time.

In conclusion, archiving CAD data is an essential aspect of managing engineering and manufacturing operations. To ensure that CAD models can be accessed and used in the future, it's important to archive them in a neutral, future-proof format such as STEP or JT. Additionally, automated validation and checking procedures should be introduced to prevent the storage of inaccurate or invalid legacy data. By taking these steps, organizations can ensure that their CAD data remains accessible, accurate, and valuable for years to come.

Long Term Archival preservation

Document any quality defects in the design model to set appropriate expectations for the reusability of the archive data. Verify that any derived forms of the design model, e.g. STEP, are equivalent in quality and shape to the master model. If using STEP, add validation properties to the STEP model which can be used by a future recipient to validate that a future translated (imported STEP) CAD model is equivalent to the master model. These validation properties could also be used to verify the equivalence of any archive data format conversions which are required to maintain the archive over time.


LOTAR is an international consortium to develop and maintain standards for long-term archiving (LTA) of 3D CAD data. These standards define archiving and retrieval processes. The documents for the standard are published as the EN 9300 series and NAS 9300 series (National Aerospace Standard).
LOTAR members are Airbus, BAE Systems, Boeing, Dassault Aviation, EADS, Eurocopter, General Dynamics, Goodrich, IAI, Lockheed Martin, SAFRAN, Sandia, and Spirit.