Work with NX files
You use Import and Export options in Alias to exchange 3D model data between Alias and NX.
Save NX part files to import into Alias
IN NX, choose File > Save Part As to display the Save Part File As window.
Specify the file name and click OK.
The NX part file is created with the file extension .prt.
Before you create the model in Alias
- Set units to mm.
- In the Construction Settings window, toggle the Rational geometry flag toOFF.
Set tolerances as follows:
- Curve Fit Distance = .01 mm (lower as necessary)
- Curve Fit Checkpoints = 10
- Max Gap Distance = .01 mm (this value should remain the same as Curve Fit Distance)
- Trim Curve Fit =.005 mm (lower as necessary)
About creating the model
- Use degree 5 curves and surfaces to achieve curvature continuity between surfaces and successful data transfer.
- Periodically transfer models from Alias to NX during construction to manage the quality of the model being created.
- Stitch the Alias model successfully before export, but also periodically stitch the geometry to ensure that the model meets all tolerance requirements.
- Avoid using Object Edit > Attach > Attach
since this tool creates multiknots in Alias geometry. - Avoid using Surfaces > Skin
between trimmed surface boundaries, since excessive amounts of data are created in the resulting surface. If Skin is used between trim boundaries, check the resulting surfaces for multiknots before export. - Use surface building tools such as Surfaces > Boundary Surfaces > Square
and Surfaces > Swept Surfaces > Rail Surface 
to ensure and control curvature continuity between surfaces.
Workflow
Before transferring geometry between Alias and NX, consider the purpose of the transfer to plan an appropriate workflow.
Two common workflows are:
- Geometry (describing mechanical components) is transferred from NX to Alias to be used as reference data for concept design surfacing, then the Alias surface model is transferred back to NX.
- An Alias model is transferred to NX, and both Alias and NX Databases are developed independently. Later, the modified Alias model is transferred again to NX, replacing the Alias geometry from the first transfer. In this scenario, all work done in NX on the first Alias model transfer will affect the new, modified geometry.
There are many variations on these two examples. Whatever the transfer scenario, carefully plan the transfer process, to ensure that the appropriate data is written out and is useful.