This is the first – and often the only – area considered by most companies. Current CAD capabilities provide robust data exchange, including standards-based methodologies such as IGES (Initial Graphics Exchange Specification) and STEP (Standard for the Exchange of Product Model Data), as well as direct translators.

However, simply using standard translators with default options will rarely provide the quality desired.

Many CAD systems make assumptions about data being imported to make it more usable. In many cases these are good assumptions, but sometimes they result in problems. Using IGES for example, solids are often exchanged as trimmed surface models. Surfaces commonly become untrimmed during the exchange and thus extend beyond the desired region. Annotation in drawings also is frequently misplaced. Text size and line weights may be incorrect. Feature control symbols and cross-hatching may be missing or misplaced.

You can approach nearly 100 percent completeness, accuracy and functionality in data exchange, if you understand and address exchange obstacles. These emerge not only from the uniqueness of CAD systems, but also from characteristics of your data. Translate a representative sample of production parts, then carefully examine the results to identify problems and explore potential resolutions. Using a different translation method can yield vastly different results. For instance, using STEP or the more recently available IGES BREP translator may provide the best results for exchanging solids.

Both STEP and IGES translators provide numerous options to determine how the CAD data is mapped to the standard and how the importing system maps the data into its native format. With a good understanding of the target system’s requirements, you can create data that is more compatible. One example is that the character font used when importing drawing data can have a tremendous effect upon text size and appearance.

Finally, you may need to perform external flavoring to achieve greater compatibility. CAD systems sometimes generate trimmed surfaces that translate with invalid trimming curves. IGES editing tools can be used to identify invalid trimmed surface definitions and regenerate the trimming curves into valid ones. CAD model healing and repair tools can be used to condition trimmed surface models into valid solids. A combination of tools may be required to achieve the best exchange.